Atch 1a. SOW Appendix B.pdf

DS/PSD/RD SOP for Blast Testing 2021

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Table of Contents

1. Scope

2. Referenced Documents

3. Terminology

4. Summary of Practice

5. Significance and Use

6. Health, Safety and Environmental Precautions

7. Facility Requirements

8. Instrumentation

9. Reaction Structure

10. Test Plan

11. Pre-Test Through Post-Test

12. Data Processing and Reduction

13. Test Report A1. Test Plan Check List A2. Revision Summary

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Standard Practice for Blast Testing

INTRODUCTION

This standard practice shall be followed for blast and shock tube testing with an aim toward maximizing the consistency and repeatability between tests and test facilities. Specific requirements are outlined related to: test configuration, instrumentation, test result processing, data reductions, facility requirements, clearing effects and fixturing or reaction structure design. As the intention is not to over-burden the test facility; any concerns or exceptions to standard practice shall be addressed in the proposal phase of projects. Exceptions shall be granted through written response from the technical program manager at the Bureau of Diplomatic Security, Physical Security Division, Research and Development Section (RD).

BACKGROUND

RD has decades of blast test experience at a wide range of facilities including several US DoD facilities, academic related facilities, private entities, and international facilities. Frequently, the various facilities exercise practices that are at best inconsistent with other facilities and often produce results that are not as well documented as RD needs dictate. The issues addressed in this document are aimed at developing consistent results and documentation between the various facilities so that direct comparison of results and identification of trends are clearly understood.

Historically, the test facilities have been provided either an explosive weight and distance or a pressure and impulse as the primary parameters to follow. There are other parameters besides weight and distance that can have an effect on the loading imposed on targets. Examples include: shape of charge, height of charge, soil or surface condition under the charge, clearing of the blast wave around the reaction structure, and the effective rigidity of the reaction structure. There is a considerable variability between test facilities as related to these parameters. Another purpose for this document is to establish standard practices to mitigate inconsistencies in methods and the possible influence on results.

Documentation of test results have often lacked important information about tested devices or systems. This document serves to highlight information that should be included in test reports. Processing of data and reporting of results are typically part of the service provided by the testing facility. However, there has been inconsistency, confusion, and debate about how best to obtain and report key information critical to the interpretation of blast test results. This document outlines a method to eliminate the debate for RD applications.

1. Scope

1.1 Purpose

The purpose of this practice is to define good commercial and customary practice in the United States of America for conducting arena format blast tests of physical security products, related devices and systems. The end goal is to harmonize results between test facilities and maximize the consistency and repeatability of the results obtained from these blast tests.

1.2 Objectives

Objectives guiding the development of this practice are:

1) Synthesize and formalize standard practices for conducting open air blast tests for RD applications.

2) Facilitate high quality, standardized results processing and reporting of test results.

3) Use the RD standard practice as a starting point for a best practice document that will grow into an industry standard both domestically and internationally.

4) It is anticipated that the scope and content of this document will change over time as requirements and facility capabilities change.

5) This document should not be considered the limit of requirements for proper completion of a given test program. There may be additional requirements depending on the application and the threat.

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1.3 Units

The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

1.4 Safety, Health, and Environmental Practices

This standard does not purport to address safety and environmental concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices in accordance with appropriate governing standards and to determine the applicability of regulatory limitations prior to use.

1.5 Omissions

The omission of any specific explosive, instrumentation type, material type or test configuration does not necessarily preclude its use in accordance with this Standard practice as long as all applicable provisions are satisfied.

2. Referenced Documents

2.1 ASTM Standards

F1642 Standard Test Method for Glazing and Glazing Systems Subject to Airblast Loadings F2912 Standard Specification for Glazing and Glazing Systems Subject to Airblast Loadings F2927 Standard Test Method for Door Systems Subject to Airblast Loadings F2247 Standard Test Method for Metal Doors used in Blast Resistant Applications

2.2 Other Standards and Manuals

ASCE/SEI 59-11 Blast Protection of Buildings Department of Defense 5220.220-M National Industrial Security Program Operating Manual (NISPOM) DOE TIC 11268 A Manual for the Prediction of Blast and Fragment Loadings on Structures Dplot User Manual GSA-TSA01 Standard Test Method for Glazing and Window Systems Subject to Dynamic Overpressure Loadings IEEE/SI 10 Use of the International System of Units (SI): (The Modernized Metric System) ISEE Blaster's Handbook, 18th Edition ISO 10012-2003 Measurement Management Systems - Requirements for Measurement Systems and Measuring

Equipment ISO IEC 17025 General Requirements for the Competence of Testing and Calibration Laboratories MIL-HBK-1013-12 Evaluation and Selection of Security Glazing for Protection Against Ballistic, Bomb and

Forced Entry Tactics MIL-STD-810G with Change 1 Department of Defense Test Method Standard Navy Blast Resistant Structures Design Manual 2.08 PDC-TR-05-01 Single Degree of Freedom Blast Effects Design Spreadsheets (SBEDS) PDC-TR-06-01 Rev 1 Methodology Manual for the Single Degree of Freedom Blast Effects Design Spreadsheets PDC-TR-06-08 SDOF Structure Response Limits for Anti-Terrorism Design UFC 3-340-02 Structures to Resist the Effects of Accidental Explosions UFC 4-010-01 DOD Minimum Anti-Terrorism Standards for Buildings UFC 4-010-02 DOD Minimum Anti-Terrorism Standoff Distances for Buildings WinGard PE User Guide

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2.3 Handbooks and Papers

Dusenberry – Handbook for Blast-Resistant Design of Buildings

3. Terminology

This section provides definitions, descriptions of terms, and a list of acronyms for many of the words used in this standard practice. The terms are an integral part of this practice and are critical to an understanding of this practice and its use.

3.1 Definitions

3.1.1 ANFO, n - An acronym for Ammonium Nitrate, Fuel Oil. A common, stable and relatively cheap explosive commonly used for blast testing. ANFO is a mixture of technical grade (TG) ammonium nitrate (AN) prills and fuel oil (FO), often #2 diesel fuel. By weight, approximately 94% AN and 6% FO.

3.1.2 Approved, adj - Acceptable to the authority having jurisdiction.

3.1.3 ATF, n - An abbreviation for Bureau of Alcohol, Tobacco, Firearms, and Explosives.

3.1.4 Blast, n - A synonym for explosion.

3.1.5 Clearing Effects, n – Clearing Effects or “clearing” is a hydrodynamic phenomenon caused by blast pressure waves diffracting around the edges of a structure which in turn generates a relief wave propagating inward from the edges. The effect of these relief waves is to reduce the amount of pressure acting on the structure during the blast event, thereby reducing the impulse placed on the structure.

3.1.6 DAQ, n - An acronym for Data Acquisition System (also known as DAS).

3.1.7 Design Basis Threat (DBT), n - The explosive type, charge size and standoff distance for design.

3.1.8 Dynamic Increase Factor (DIF), n - A factor, greater than 1, applied to expected material strengths to account for high strain rate effects.

3.1.9 Dynamic Response, n - Deformation, stress and other behavior of structure or structural element due to the action of a time-varying loading while considering inertial, stiffness, and, in some cases, damping effects.

3.1.10 Equivalent Weight of TNT, n - one measure of the energy (power) contained in a given amount of a specified explosive expressed as the weight of TNT which would result in the same peak pressure or impulse, all other parameters being equal. A number generally ranging between 0.7 and 1.7. Note that for some explosives the equivalent weight can differ depending upon whether comparing peak pressures or impulses.

3.1.11 Explicit Finite Element Analysis, n - Finite Element Analysis in which dynamic response at a given time is expressed in terms of displacements, velocities, or accelerations at previous time steps.

3.1.12 Explosion, n - A rapid chemical reaction that produces noise, heat, and a rapid violent expansion of gases.

3.1.13 Explosive, n - A material or device that is capable of causing an explosion under certain conditions, such as heat, shock, electrostatic discharge or friction.

3.1.14 Far Range, n - Standoff at which the blast loading from an explosion can be considered to be uniformly distributed over the tributary area of the element to be loaded. This corresponds to a scaled distance Z that is equal to or greater than 1.2 m/kg^1/3 (3.0 ft/lb^1/3).

3.1.15 Fixturing, n – Devices or assemblies that may be used as interfaces between the test article and the test frame or reaction structure. Most often the fixturing is intended to provide realistic local support conditions for the test article.

3.1.16 Generally Accepted Practice – Generally accepted practice in this document corresponds to means or methods that are commonly known or generally accepted in the community of blast effects on structural devices and systems.

3.1.17 IME, n - An abbreviation for Institute of Makers of Explosives.

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3.1.18 Implicit Finite Element Analysis, n - Finite element analysis in which the dynamic response of each node at a given time is expressed in terms of all the displacements, velocities, or accelerations at that time.

3.1.19 Impulse, n - Cumulative blast loading over time, calculated as the area under a pressure-time plot.

3.1.20 ISEE, n - Abbreviation for International Society of Explosives Engineers.

3.1.21 ISO/IEC, n - Abbreviation for International Organization for Standardization and International

Electrotechnical Commission.

3.1.22 Near Range, n - Standoff at which the explosive is in close proximity to the structure relative to the size of the explosive, such that the resulting blast loading must be considered to be non-uniformly distributed over the tributary area of the element being loaded. This corresponds to a scaled distance Z that is less than 1.2 m/kg^1/3 (3.0 ft/lb^1/3).

3.1.23 NIST, n - An acronym for the National Institute of Standards and Technology.

3.1.24 Nonreactive, adj – Often used to describe a reaction structure and test frame. Non-reactive is a term used to describe a support system wherein the response of the support structure does not influence the response of the tested article.

3.1.25 NVLAP, n - An acronym for National Voluntary Laboratory Accreditation Program, administered by

NIST.

3.1.26 Penetration, n - Disruption or displacement of some of the target material by a fragment that impacts but does not pass through the target.

3.1.27 Perforation, n - Passage through the target material by a fragment during impact.

3.1.28 Recognized Literature, n - Published information including, but not limited to, research findings, technical papers, and reports that are approved by the Authority Having Jurisdiction.

3.1.29 Reaction Structure, n – A structure used to support the test article, test frame and fixturing during the blast event. The reaction structure normally has large mass and stiffness compared with the anticipated loading and response of the test article. Examples include reinforced concrete boxed-shaped rooms, reinforced concrete culverts or containers filled with soil positioned behind the test frames. Another example may be a test frame mounted to a sled with the sled held in place by concrete blocks or possibly sand bags.

3.1.30 Rigid, adj – Most often used to describe a structural component or system that has very high strength and very small deformations or deflections relative to the loading and accordingly has a very small effect on the response of the test article.

3.1.31 Scaled Distance Z, n - The ratio of the standoff to the cube root of the explosive charge size as an equivalent mass of trinitrotoluene (TNT), which commonly serves as the basis for determining the blast loading parameters.

3.1.32 Standoff, n - The physical distance between the surface of a building, or part thereof, and the potential location for an explosion. Most often the standoff is measured to the center of the charge. As there may be exceptions, it is important that the standoff be clearly defined in the test plan.

3.1.33 Test Agency, n – Organization, company or laboratory charged with the task of planning and executing the test(s) and with producing the appropriate deliverables related to test(s).

3.1.34 Test Article, n - Device or system being tested or evaluated.

3.1.35 Test Facility, n – Physical infrastructure, equipment, items, and devices required for the execution of blast tests including geographical area (blast range), reaction structure, instrumentation, equipment, tools, power sources, and the like.

3.1.36 Test Frame, n – A test frame is often used as a means of structural connection between the test article and the reaction structure. Test frames are most often constructed from either reinforced concrete or steel assemblies.

An example would include a tilt-up reinforced concrete wall placed in front of and rigidly attached to a reaction structure. The test article may be attached directly to the test frame or there may fixturing included to serve as the interface between the test frame and the test article.

3.1.37 Validated Constitutive Model, n - A constitutive model is validated for a range of calculations if it is known top consistently and repeatedly produce results and predictions in agreement with what has been observed in real situations covering that range of applications.

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3.1.38 Witness Panel, n - A panel placed on the protected side of a test article that is used to document spall or fragmentation, typically from a test article containing glazing.

3.2 Symbols and Notation

ANFO - Ammonium nitrate, fuel oil Cr - Sound velocity in reflected overpressure region, m/ms (ft/msec) CFD - Computational fluid dynamics COTS - Commercial-off-the-shelf C4 - Composition 4 If - Free field gas overpressure impulse, MPa-ms (psi-msec) Ir - Normally reflected gas overpressure impulse, MPa-ms (psi-msec) MDOF - Multi-degree-of-freedom Pf - Peak free field gas overpressure, MPa (psi) Pr - Peak reflected gas overpressure, MPa (psi) Pso - Peal side-on or incident gas overpressure, MPa (psi) R - Standoff, m (ft) SDOF - Single degree-of-freedom t - Time, ms (msec) td - Duration of positive phase, ms (msec) tof - Equivalent triangular duration of positive phase incident pressure, ms (msec) tc - Clearing time, ms (msec) tg - Equivalent duration of gas overpressure, ms (msec) trf - Equivalent triangular duration of positive phase normally reflected pressure, ms (msec) TNT - Trinitrotoluene Us - Shock front velocity, m/ms (ft/msec) W - Explosive size as an equivalent quantity of TNT, kg (lb) Z - Scaled distance, R/W^1/3, m/kg^1/3 (ft/lb^1/3)

4. Summary of Practice

4.1 Guidance on Facility and Test Configuration

4.2 Guidance on Test Procedures

4.3 Guidance on Data Processing, Documentation, and Report Generation

5. Significance and Use Uses – This practice is required for RD open air blast tests. Any deviation or exception to the practice should be addressed as early in the planning stage as possible and shall require written approval by the RD program director.

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6. Health, Safety and Environmental Precautions It is the responsibility of the test facility or organization to address all health, safety, and environmental concerns in accordance with appropriate governing standards, organizational standards and / or generally accepted practice.

7. Facility Requirements

7.1 Topography – The topography immediately adjacent to the location of the explosive charge must be approximately level (1 m rise or fall in 100 m) from the charge to 25% of the standoff past the target within an arc encompassing 30 degrees on either side of the reaction structure. Additionally, the area outside the arc shall be clear of any geometrical shapes or items that may inadvertently cause reflective or secondary loads on the target.

7.2 Camera Vantage Points – The test range shall provide sufficient camera vantage points situated to have an unobstructed view of all active test (reaction) structures and of the charge location. The vantage point(s) shall be sited so as to offer a side view of the hemispherical blast wave striking the front of the test (reaction) structure with at least one (1) camera for each active test (reaction) structure. As the blast test plan may dictate and further specify, other camera vantage points may be sited as needed to provide other views.

7.3 Blast Pad – Beneath the charge location, a blast pad shall be provided to minimize the influence of the local soil and/or substrate on the blast test results. The blast pad shall consist of either a concrete slab or a steel plate. Unless directed otherwise the concrete pad shall be 244x244x23 cm (8′x8′x9″). Concrete pads shall be normal-weight concrete and shall have a 28-day compressive strength of no less than 20.7 MPa (3000 psi).

Concrete blast pad reinforcement requirements are the responsibility of the test agency but shall be a minimum of 10M @ 46 cm (#3 @18″) c/c each face and each way. The optional steel plate shall be 244x244 cm (8′x8′) with a minimum thickness of 25 mm (1″). It shall be made in one piece (by welding plates together if required) and shall be made of ductile steel (A36 or similar). The blast pad shall completely bear upon firm in-situ soil. The top face of the blast pad shall not protrude more than 50 mm (2″) about the surrounding grade. In cases of repeated tests, blast pads may be re-used with careful evaluation of condition after each test. An exception to requiring blast pads may be considered in cases where extremely hard and durable substrate is within 12″ of the surface under the charge (shallow bedrock as an example).

7.4 Clean Power – All powered equipment at the test range, whether at the cameras, sensors, data acquisition system, or in the control bunker shall be supplied with “clean” filtered power such that sensor signals are not cluttered with extraneous electrical noise.

7.5 Handling of Explosives – The test facility shall have written procedures for handling, storing, tracking, and disposing of explosives. Minimum record maintenance should include purchase or shipment: the purchase date, lot number, vendor name, and specific technical information regarding explosive yield. For ANFO, non-uniformity of the product such as “clumping” or “caking” of the prills shall be considered as defects and shall not be used under the scope of this standard. Unless specified by the manufacturer the, the use-by date for ANFO is defined as 6 months from date of purchase and not to exceed 9 months from the date of manufacture.

8. Instrumentation Instrumentation requirements may vary considerably based on the nature of the test article and the load condition of interest. This section provides general guidance for devices as they are applicable to a given test.

8.1 Pressure Transducers – Pressure transducers shall be provided in accordance with ASTM F1642-17.

Additionally, pressure gauges shall be mounted so as to minimize localized clearing effects (e.g., mounted flush with the face of the reaction structure) and structural response induced noise. Techniques involving covering the front of the gauge with soft materials like tape or silicone grease may be used to mitigate extraneous noise only accompanied by clearly documented evidence that the technique does not significantly affect the pressure wave measurement.

8.2 Displacement Measurements – Displacement measurements may be obtained by some combination of the following devices or methods. In general, displacement gauge accuracy, measured range of movement, and sampling rate should be selected in accordance with the predicted movements of the tested device. General comments regarding application and challenges include:

8.2.1 Optical / Laser Gauges – Gauges may be used in cases where debris and dust do not interfere with the signal. Excessive movement of the measurement point may also cause the signal to be lost mid-test. Flash from

SOP for Blast Testing 2021 UNCLASSIFIED 07/11/2021 Page 8 of 15 explosive detonation may also need to be addressed to avoid interference with proper signal. This is typically accomplished by covering any transparent test specimen with an opaque covering.

8.2.2 Rod Deflection Potentiometers – Rod deflection potentiometer gauges (rack and pinion gauges) are often used in blast testing, especially where there is considerable dust and debris. Three concerns include attachment of the rack to test article, column buckling of the rack, and whip of the rack during the response. Attachment of the rack to the tested article shall not damage the article (particularly in the case of glass) and must provide for displacement measurement through inbound and outbound response of the tested article. The rack shall be stiff enough to minimize buckling and / or lateral whip that can affect displacement measurement. The mass of the rack should be as small as practicable so as to minimize the possible effect on dynamic response of the tested article.

8.2.3 String Potentiometers – String potentiometers (cable-extension position transducers also known as yo-yo gauges) may be used with the caveat that the rate of cable recoil is limited to a maximum acceleration. Exceeding that acceleration can result in measurement error or, in the case of backlash, total measurement loss. Also, the device is sensitive to small debris and dust interfering with the cable movement or introducing extraneous cable movement thereby effecting the displacement measurement.

8.2.4 Accelerometers – Accelerometers (discussed below) may be used to measure acceleration at key locations with displacements calculated via two numerical integrations to calculate velocity and displacements. The results are often useful to “scale” movements and serve as backup to other direct measurements.

8.2.5 Global Movement of Reaction Structure – The global pre- to post-test movement of the reaction structure shall be measured relative a fixed reference. The intent is to document net movement due to sliding or shift of the structure resulting from the applied blast load. The measurement accuracy shall be within +/- 1/8″.

8.2.6 Other Displacement Measurements – Various other techniques may be employed like fiducial markers coupled with high-speed cameras or strain visualization techniques. A completely different technology involves piezo pin sensors that may be used to measure global displacements by activating when contact is made with the piezo material in the tip of the pin. In blast application the pins are often destroyed. In all cases, there shall be well documented evidence regarding the efficacy of the method.

8.3 Acceleration Measurements – Accelerometers may be used to characterize response versus time for the tested device or for the reaction structure. Care should be taken regarding general issues like sensitivity, amplitude range, decay time, drift, and mounting. It is especially important that the linear frequency range of the accelerometer encompass the primary response frequencies of the tested device coupled with the reaction structure.

8.4 Direct Force Measurement – Direct force measurement may be obtained through strain measurements of key structural components or implementation of load cells. In the case of load cells, the range and sensitivity of the load cell must capture the force response over both the inbound and outbound portions of the response.

Accordingly, any preload applied before the load event must be large enough to account for rebound loading. A critical consideration is the mounting of the load cell. Any residual permanent displacement that may influence the accuracy of the load cell force measurement shall be limited to less than 5% of the gauge displacement corresponding to the maximum force measured.

8.5 Strain Measurement – Strain measurements are most reliably obtained using strain gauges mounted directly to structural components. The selection of the gauges must include consideration for the material and surface being instrumented as well as the range and linearity of strain values. Particular care must be taken when strains exceed the elastic limit of metals. In all cases the strain gauges shall be selected, installed, protected, and instrumented in accordance with generally accepted practice and the gauge manufacturer’s recommendations.

Optical strain measurement and strain visualization techniques may be used when supported by well documented evidence regarding the effectiveness of the techniques in applications similar to the planned test.

8.6 Temperature Measurement – Temperatures of the tested device may be measured using suitable devices including thermocouples, infrared camera, and the like. The primary concern is that key tested article temperatures are measured and recorded as close as possible to the time of detonation.

8.7 Photographs – Digital photographs shall be taken with a camera having a minimum resolution of 8 megapixels.

8.8 Video – Various videos may be required using a combinations color, black & white, real time, high speed and disposable cameras. In this context a high-speed camera shall have a frame rate of no less than 1000 frames per second. High speed video shall include a time counter on the video suitable for measuring time steps between

SOP for Blast Testing 2021 UNCLASSIFIED 07/11/2021 Page 9 of 15 frames. Time counter on all video shall reference time zero (0:00) from time of detonation unless otherwise specified (see Section 12.3).

8.9 Witness Panel – A witness panel is often required as a means of qualifying and quantifying the amount of fragmentation that either passes or is expelled from the tested article. The specific materials of construction and configuration of the witness panel shall be documented.

8.10 Redundancy and Correlation – As much as practicable, a variety of gauges or gauge types shall be used to provide redundancy particularly in cases where gauges or gauge signals may be lost during a test.

Correlation between, for example, accelerations and global movements or strains and displacements may be facilitated through careful selection and placement of gauges.

8.11 Mounting Cameras and Sensors – Cameras and sensors shall be supported or attached in such a manner as to minimize spurious dynamic movements that may clutter or bias images or data.

8.12 Data Acquisition System (DAQ) – The DAQ shall consist of a digital recording system with a sufficient number of channels to simultaneously accommodate the desired number of sensors and transducers. The DAQ shall operate at a sufficiently high frequency to reliably record the peak positive pressure. The DAQ shall also incorporate filters to preclude alias frequency effects on the data.

8.13 Calibration and Validation

8.13.1 Calibration – All sensors (pressure, deflection, acceleration, etc.) shall have been calibrated by the sensor manufacturer per the manufacturer’s recommendation but not more than 2 years prior to the test date. All calibration records shall be made available upon request of RD.

8.13.2 Pre-test Check of Instrumentation – Bench top testing of sensors and instrumentation shall be performed prior to but not to exceed six (6) months before the test time. The results shall be compared against standard signals or measurements to demonstrate a consistency within 2% of the standards. Documentation of the pre-test check shall available to the RD before the test and shall be included with the final report.

8.13.3 Modifications to Test Plan – RD shall be notified of any modifications to the test plan as well as changes to instrumentation and test article condition. There shall be as much notice as practicable for evaluation of the possible impact on results. If there is the potential for negative impact on the results, the test may need to be rescheduled until the issue can be remedied.

9. Reaction Structure

9.1 Non-Reactive Structure – The test article, device or system shall be supported by a structure deemed as non-reactive. Non-reactive is a term used to describe a support system wherein the response of the support structure does not influence the response of the tested article. Ideally, in numerical terms, the maximum dynamic displacement of any and all interface points between the test article or fixturing connection to the test frame and the reaction structure shall be limited to 5% of the maximum displacement of the tested article. In addition, the period of the lowest frequency mode shape indicating movement of the interface front shall be limited to the predicted positive phase duration (td) divided by twenty (20). Numerical results may be demonstrated by calculation or prior test results and be presented with appropriate documentation provided prior to the test.

9.2 Elastic to the Load – Components of the support system including the reaction structure and the test frame shall remain “elastic to the load” during the test. As such there shall be no significant permanent deformations. Supporting calculations or previous test results are required to be submitted prior to the test.

Incidental yielding like small cracks in reinforced concrete panels or localized yielding of support system connections may be acceptable. In all cases, acceptance of incidental yielding shall be at the discretion of the RD program manager and shall be documented in writing.

9.3 Fixturing and Test Article Mounting – Fixtures and mounting devices used to facilitate the structural interface and installation of test articles with the reaction structure shall be consistent with manufacturer recommendations or applicable design drawings. In the absence of either, calculations shall be performed and submitted that demonstrate the adequacy of the mounting scheme. Additionally, any deviation from manufacturer recommendations or design drawings shall be documented. Examples of deviations might include through-bolted connects in lieu of drilled and tapped connections or expansion type concrete anchors in lieu of epoxy anchors.

9.4 Global Movement Mitigation – Consistent with the notions above, the test frame or reaction structure shall be designed or configured to minimize global movement particularly in the form of horizontal sliding. As the

SOP for Blast Testing 2021 UNCLASSIFIED 07/11/2021 Page 10 of 15 global movement is part of the total limit in the non-reactive structure paragraph above, it is strongly recommended that steps be taken to mitigate global movement. The movement of the reaction structure relative to a fixed reference point shall be measured and documented from pre- to post-test.

9.5 Face of Reaction Structure – In general terms the face of the reaction structure shall not have holes or voids that might allow leakage of blast pressure through the face. There shall be no appurtenances or divots that might introduce localized shock wave eddies or clearing particularly in close proximity to pressure gauges. Pressure transducers shall be mounted flush with the face of the structure.

9.6 Reflections – If more than one test structure is located in the blast arena, consideration shall be given as to whether the proximity of the nearby structure(s) or changes in topography and possible blast wave reflections might have a detrimental effect on the test results.

9.7 Enclosed Space Behind Test Article –If the test article is designed to function with an enclosed space behind it, such as would be the case for the outer wall system of a building, then the reaction structure shall feature an enclosed space immediately behind the test article. The enclosed space shall serve both to simulate interior building space and provide access to, and protection of instrumentation. The design shall be such that pressure waves wrapping around the test structure will not be able to enter the enclosed space and load the back side of the test articles.

9.8 Clearing Effects – The reaction structure shall be proportioned or shall have contiguous structure for a suitable distance from the edges of test article such that the clearing effects do not cause significant reduction in the reflected impulse at the test article. Planned mitigation of the clearing effects shall be documented prior to the test and shall be supported by either calculation or by previous test results.

9.9 Reaction Structure Construction Specifics – In some cases, RD may require specific information regarding the construction of the reaction structure so as to facilitate modelling where dynamic coupling of the test article with the reaction structure may be of concern. The specific information would be in the form of material of construction, mechanical properties, member sizes, and connection details.

10. Test Plan A test plan is required for submission to RD with ample calendar time to allow at least one review and comment by RD with final edit by the testing organization. RD shall have final approval of the test plan. The test plan shall include the following components:

10.1 Test Article(s) – A general description of test article shall be included. Supporting drawings, sketches, calculations, and background information shall be included in an appendix. Details should be included or documents should be referenced that provide enough specific information such that the article can be reproduced or reconstructed without any specific knowledge regarding the article. Documentation shall address fixturing and mounting of test article as discussed above.

10.2 Blast Loading – Blast loading will either be defined in terms of TNT equivalence and standoff, or reflective pressure and impulse. Note that in either case, it may be required to present the explosive load in symbolic form with no explicit values shown. In that case, separate communications with RD may be required to document the values. Sketches drawn to scale shall be included that show the proximity of the charge to the target(s) and the reaction structure with, at a minimum, an outline of the reaction structure frame drawn to scale.

The sketch shall include any clearing effects mitigation that may be included.

10.2.1 Specified TNT Equivalence – In the case of TNT equivalence for explosive materials, there shall be documentation provided to support the equivalent values with consideration for standoff distance. Given that TNT equivalence may differ for pressure versus impulse, there should a clear understanding and associated documentation regarding what combination of pressure versus impulse is assumed.

10.2.2 Specified Pressure and Impulse – The test plan shall include documentation from previous tests or specifics details of how calibration tests will be executed as part of the preparation for the actual tests. Typically, calibration tests include gauges installed on panels that act as surrogates for the actual test articles. As direct measurement of pressure and impulse on the test article may not be practical, gauges shall be installed near the edge of the test article for both the calibrations tests and the actual tests. Those gauges may then be used to evaluate the loading likely applied to the test article. Since pressure gauges have a propensity to yield spurious data, redundancy in pressure measurements is highly recommended. Provide redundancy by symmetric placement of gauges relative to the test article. Gauge redundancy should be taken into account to mitigate damaged or non-functioning gauges

SOP for Blast Testing 2021 UNCLASSIFIED 07/11/2021 Page 11 of 15 during the test event. The calibrated target reflected pressure and impulse shall be within +/- 10% of the specified reflective pressures and impulse. Note that the calibrated reflective pressure and impulse shall be derived from a Modified Friedlander curve fit of the positive phase raw pressure data.

10.2.3 Shape and Configuration of Charge

10.2.3.1 TNT Equivalence 250 lb. or Greater – Most often for TNT equivalent charges of 250 lb. or greater the charge shape shall be that of a cylinder with the axis of the cylinder oriented in the vertical direction. The height to diameter ratio shall be as close to one (1) as practicable. In the case of granular or prilled explosives like ANFO, the material is typically poured into a cylindrical cardboard tube as would be used for forming cylindrical concrete columns. The charge shall be placed on top of a frangible table with a height of 32″ from the ground surface.

10.2.3.2 TNT Equivalence Less than 250 lb. – For TNT equivalent charges of less than 250 lb. the shape and configuration of the charge may vary considerably. The default configuration is as described above for 250 lb. or Greater. If the configuration is not explicitly provided in the statement of work, the testing agency shall confirm the configuration prior to submitting the test plan for review.

10.2.3.3 Specified Pressure and Impulse – In cases where a target reflective pressure and impulse is specified, it shall be at the discretion of the test facility to select the charge shape and configuration.

10.2.4 Explosive Weight – In all cases, the actual weight of the explosive shall be within +/- 1% of the planned weight of the explosive. The actual net weight shall be recorded and documented. As an example, in the case of ANFO, the facility might document the weight of each loaded bag minus the weight of each empty bag or the weight of a pallet loaded with full bags minus the pallet with the emptied bags.

10.2.5 Detonation – Provide a description of the detonation plan including the type and placement of the detonator. In general, center detonation is considered the default method; this may be altered with the approval of the RD program director.

10.3 Instrumentation Plan – Sketches and other documentation shall be provided that indicates sensor type and location as well as camera placement. Technical data sheets for the various sensors, cameras and the DAQ shall be included in an appendix.

10.4 Reaction Structure – Sketches shall be included that show the overall dimensions of the reaction structure including opening sizes, internal dimensions, clearing effects mitigation, and reference points for global movement of the reaction structure. The mass of the reaction structure shall be documented. Supporting documentation shall be provided regarding the structural response of the reaction structure as related to it and ancillary components being nonreactive and elastic to the load. Provide documentation in the form of calculations or previous test reports that support the mitigation of clearing effect on the load at the target(s).

10.5 Witness Panel – As witness panels may be required in some tests, witness panel dimensions, location and construction details shall be included. Sketches showing an elevation view of the target with a to-scale outline of the corresponding witness panel shall be included.

11. Pre-Test Through Post-Test

11.1 Test site visit by RD – In addition to pre-test walk though, test witnessing and post-test review of results, RD may opt for additional test site time including:

11.1.1 Being present during portions of the test article installation and test set-up for observation and possible test article or test plan refinements.

11.1.2 Performing walk through and observation the day before the test where final adjustments and refinements to the setup may be requested.

11.1.3 Performing post-test forensics on the day(s) after the test event.

11.2 As Tested Article

11.2.1 Fabrication – The as fabricated test article shall be fully documented as related to deviation from the design drawing, sketches, or calculations. Any available insights into possible improvement in details as related to ease and cost of fabrication should be noted.

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11.2.2 Installation – The as installed configuration shall be fully documented with particular attention to issues like shim gaps and bolt torques. Any deviation manufacturer recommendations or installation details shall be documented. Any possible insights into modifications to facilitate installation shall be documented.

11.2.3 Materials of Construction – All test articles, fixturing and mounting supplied by the testing organization shall be fully documented as to the as tested mechanical properties. There is a distinction between as designed, specified or ordered properties and the actual as tested properties. An example is that of structural steels where the actual yield and tensile strengths are much higher that the specified minimum. Proper tracking and documentation of steel product includes mill test reports for the specific lot of steel where yield, tensile and elongation are reported. Another example is the need to require documentation of bolt strength certification. A further example is that as placed concrete strength is most often much higher than the as ordered concrete. Twenty-eight (28) day compressive tests shall be executed and documented for the as placed or as constructed concrete.

Glazing layups as well glass, polycarbonate, interlayer, structural silicone, and gasket component mechanical properties shall be documented.

11.3 Reporting Deviations – In addition to documenting any deviations in the test plan or test article, the deviations shall be communicated to RD before the test is executed. That communication shall include visual observation at the test site before the test when appropriate.

11.4 On Site Documentation by RD – The program director for RD shall have full authority over whether visitors are allowed to photograph or video any aspect of the test setup, execution and results. The testing organization shall have the right to control or review and delete background and surrounding images that may not be germane to the test.

11.5 On Site Review of Results – RD shall be given the opportunity to review data including videos as soon as practicable after the test. Technicians shall be available to obtain selected peak pressures, displacements, and the like while RD is still on site. Video play backs shall also be available to RD before leaving the site.

11.6 Range Safety –The range safety officer (or equivalent) shall have authority over access and conduct of visitors in issues where there may be a concern over human safety or health.

12. Data Processing and Reduction

12.1 Raw Data – All raw data from all sensors, recorded during both calibration blasts and test blasts, shall be retained in digital form and be delivered as supplementary information to accompany the final Test Report.

12.2 Processed Data – Any processing or reduction of raw data in the form of curve fits, smoothing, shifting and truncating shall be documented with complete details describing the specific steps or mathematical operations involved.

12.3 Time Scale – All sensor data and video recordings shall have synchronized time scales with time zero at time of detonation. The time scale shall be truncated to td before detonation until the end of the negative phase and until significant test article response has ended.

12.4 Videos – Videos shall have a duration that capture the event but shall be truncated so as to minimize length and storage requirements. The time scale shall be truncated to 2 seconds before detonation until the end of the negative phase, until significant test article response has ended and or until the shock wave and debris have dissipated or settled. Title slides shall be visible no longer than 2 seconds followed by a 2 second delay before the shot initiation. Videos shall be saved in a format that is readily viewable using common software tools.

12.5 Peak Pressure Definition – In addition to plotted curves for blast pressure versus time, peak pressures at the various sensors shall be obtained and tabulated using a Modified Friedlander curve fit for the positive phase of the blast pressure versus time history data. Other forms of curve fits may be used, for example, for the negative phase of the pressure curve. However, to re-emphasize, for RD purposes, the reported values for peak pressure are to be derived explicitly from the Modified Friedlander form and the positive phase data only. The curve fit shall be shown on the curves included in the report, and a digital form of the processed data with curve fits shall be included as a deliverable with the final Test Report.

12.6 Impulse – Impulse shall be calculated by integration of the pressure versus time data. As a check on the curve fit to the positive phase, it is suggested that the curve fit result be integrated for comparison of peak impulse from the integration of the actual pressure data.

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13. Test Report

13.1 Any and all references in this specification to documentation or deliverables including test plan, calculations, drawings, sketches, measurements, component properties, results, observations, deviations, photos, witness panel results, data plots, raw data, processed data and videos are to be included in the main report, as appendices of the main report or referenced by the report. Referenced information shall be delivered to RD as part of the report package. Exceptions include third party documents of standards that are protected by copyrights. All raw and processed data shall be provided in digital format as part of the report package. Digital forms of plotted data shall be provided in Dplot format. Dplot graphs shall be generated to include axis descriptions, units, and graph title. Copies of the Dplot graph shall be provided in PDF format.

13.2 Other results that shall be included as applicable or as data is available:

- Metrics for assessing test results (e.g., operability of doors or fragmentation of glass).

- Summary tables comparing predicted values of loading and responses with measured values.

- Any instrumentation failure or measurement anomalies shall be documented.

- Documentation of process used to smooth, filter and curve-fit sensor data.

- Documentation of the post-test condition of fixturing, mounting systems, and reaction structure including fasteners, weldments, concrete components, and concrete anchors.

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ANNEX

(Mandatory Information)

A1. TEST PLAN CHECKLIST

Item (documentation) Yes No N/A Comments Test article details Sketch of charge relative to target TNT equivalence P&I calibration Shape and Configuration of Charge Explosive weight documentation plan Detonation plan Instrumentation plan Technical data for instrumentation Reaction structure dimensions Reaction structure response calculations Non-reactive and elastic to the load Clearing effects mitigation Witness panel sketches and details Test plan checklist

N/A – Not Applicable

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A2. REVISION SUMMARY

Release 07/11/2021

Paragraph 8.8 – Added “High speed video shall include a time counter on the video suitable for measuring time steps between frames.”

Paragraph 11.2.3 need to add language for glass strength

Paragraph 12.3 – Added “with time zero at time of detonation”

Added Paragraph 12.4 Videos