Attachment 1 - Technical Specification Sheet.pdf

DRAFT

TECHNICAL SPECIFICATION SHEET

For a 2.5-inch High Capacity Force Balance

This Statement of Work describes the requirements for the completed internal balance.

1.0 Introduction

1.1 This Statement of Work describes the requirements for a six-component strain gaged balance. The balance will be state of the art in all areas of design, fabrication, gaging, and calibration. The balance will be guaranteed to be free of defects in design, fabrication, and calibration for one year after the balance is delivered. The balance will be interchangeable with the balance 6-2.5-5.00-2.00M-H,I (MC-96H-2.50-B,C).

2.0 Balance Load Rating

2.1 Balance rated static capacity:

Normal Pitching Side Yawing Rolling Axial

Force (NF) Moment (PM) Force (SF) Moment (YM) Moment (RM) Force (AF) lbs. in-lbs. Lbs. in-lbs. in-lbs. Lbs.

@ 0 PM @ 0 NF @ 0 YM @ 0 SF

±10,000* ±32,500* ±5,000* ±16,250* ±18,000* ±800*

(The above loadings are for PM and YM referenced to the balance center)

* Loads, may vary to meet factor of safety considering design and material properties

2.2 Failure Safety Factor

2.2.1 The balances shall be designed for a safety factor of at least 3.0 on yield for simultaneous application of the rated full-scale loads on all components.

2.2.2 The balance shall be designed to have a dynamic safety factor of 1.5 at the rated load.

The goodman lines shall be provided.

2.3 Stress Analysis

2.3.1 A detailed stress report identifying the critical areas of the balance will be provided

2.3.2 A Finite Element Analysis (FEA) representative of the as built balance hardware will be performed in compliance with industry standards

2.3.3 The FEA model will be made available to the recipients of the balance hardware or access to the FEA will be provided upon request

2.3.4 The solid model geometry sufficient to create an FE model will be provided for use by

AEDC

2.4 Quality, Testing, and Certification

2.4.1 A quality inspection summary will be provided showing that the balance hardware meets design specifications within accepted manufacturing tolerances

2.4.2 Adequate certification of the stress analysis will be performed through one or a combination of three methods

• Non-destructive inspection of the finished hardware to certify the absence of any flaws that would alter the stress analysis

• Destructive methods that characterize the balance hardware material properties and certify the accepted static and dynamic limits

• An independent third party will review the stress analysis, certify the accepted static and dynamic limits and safety factors. This report will be provided to AEDC.

3.0 Electrical Characteristics

3.1 Excitation

3.1.1 The vendor shall specify the recommended excitation voltage, 5 VDC is preferred.

3.2 Sensitivity

3.2.1 The minimum output of each component will be 0.3 mV/V. With any exceptions being noted

3.3 Residual Zero Unbalance

3.3.1 The zero load output of each component shall not be greater than 0.25 mV/V.

3.4 Signal Isolation

3.4.1 The components shall be electrically independent from each other and isolated from ground by at least 5000 meg Ohms at 15 volts.

3.5 Strain Gages

3.5.1 All strain gages shall be foil type epoxy bonded, wired into four arm bridges.

3.5.2 All gages for a given balance bridge shall be from the same lot number.

3.5.3 All gages and connections shall be sealed for moisture and corrosion protection.

3.5.4 Bridges may be wired in parallel to improve balance performance.

3.6 Balance Cable

3.6.1 The cable shall contain stranded Teflon coated wires twisted in pairs. Excitation power leads shall be 28 gauge or larger. Excitation sense, monitor, and signal leads shall be 32 gauge or larger with the following color code. Common voltage will be used for the balance excitation.

Lead Positive Negative

Excitation Power Input (all bridges) Red Black

Sense (all bridges) Red Black

Monitor (all bridges) Red Black

Lead Positive Negative

Signal Normal Forward Green Gray

Normal Aft Green White

Side Forward Green Yellow

Side Aft Green Orange

Rolling Moment Green Brown

Axial Force Green Blue

The leads for the temperature sensors shall be clearly identified and distinguishable from the strain gage leads.

ID Location Positive Positive Negative Negative

PRT 1 Fwd Metric Red Green Black Brown/White

PRT 2 Fwd N-Metric Red Green Black Orange/White

PRT 3 Aft Metric Red Green Black Blue/White

PRT 4 Aft N-Metric Red Green Black Violet/White

3.6.2 The cable shall be a minimum of 120 feet long, and sheathed with expandable nylon.

3.6.3 The cable, including the sheath, will be less than 0.50 inches in diameter.

3.6.4 The end of the cable will be terminated with stripped lead wires.

4 Mechanical specifications

4.0 Deflections

4.0.1 Deflections are to be held to a minimum.

4.0.2 Angular measurements of the first and last zero load point of a load sequence should vary no more than 0.01 degrees.

4.0.3 Deflection data and constants will be provided.

4.1 Calibration Hardware

4.1.1 The balance will be compatible with existing 2.5 inch calibration hardware.

5.0 Temperature Requirements

5.1 Temperature compensation

5.1.1 The maximum output of any component shall not exceed 0.2% of Full Scale, (~.005 mV/V), at stabilized conditions over the range of 70 to 150 degrees F.

The axial component output shall be compensated prior to assembly. The assembled balance may have slightly larger outputs on axial component that may exceed this requested value.

5.2 Maximum operating temperature

5.2.1 The integrity of the balance will not be compromised when exposed to sustained temperatures of 200 degrees F.

5.3 Temperature Sensing Devices

5.3.1 Temperature sensing devices shall be installed in order to determine the temperature distribution within the balance. This will require sensors in at least 4 locations on the balance.

5.3.2 The temperature sensors shall be of the 100 Ohm platinum-resistance type (RTD / PRT).

6.0 Balance Calibration Requirements

6.1 Loading Requirements

6.1 The components shall be loaded by applying dead weights in precise locations to achieve full range loads. Each position will be loaded in 4 to 5 increments from zero to a full load condition. Normal and Side Forces will be loaded at five locations in both the positive and negative directions. Axial and Roll will be loaded in both the positive and negative directions. All other loadings which may be necessary will be included in the calibration.

Normal and side planes and roll will be loaded in both the positive and negative directions without preloading to document hysteresis. Axial will be loaded in the positive direction to document hysteresis. Each component will be loaded in 4 to 5 increments from zero to a full load condition.

The balance may be loaded with a combination of dead weight and hydraulic loads to meet the load requirements of each position in the normal and side planes.

The Balance data will be used to derive the equation constants for converting the data to engineering units.

The form of the equations and the loading schedule and all raw data will be supplied with the calibration report.

6.1.1 Drift

The balance components will be loaded individually to at least 50% of the maximum load.

The loaded condition shall be recorded for 15 minutes at 1 minute intervals to document the drift/creep characteristics of each bridge. The bridge outputs will not vary more than 0.20% over the 15 minute duration.

6.1.2 Sensitivity

The sensitivity will not vary more than 0.15% at stabilized conditions over the range of 70 to 120 degrees F. The results will be reviewed with the technical POC, to decide if using a math function to correct any error in excess of the .15% target is required.

6.2 Calibration Accuracy

6.2.1 The data from the calibration will be used to compute the load values, which will be compared to the applied load. The standard deviation of the errors computed from the back calculated calibration data should be less than 0.15% of Full Range load.

7.0 Performance Verification

Documentation The test results from all loadings shall be included, as well as the data from the temperature performance verification. The constants, equations and standard deviations will also be included. All data will be provided in Excel for Windows file format.

The following shall also be included:

Electrical diagram, and color-code Two copies of the stress analysis to support the safety factor ratings.

The internal geometry for FEA not to be released beyond AEDC.

Drawings of assembled balance defining the balance envelope and dimensions for interfaces. This drawing will be releasable by AEDC and not marked as proprietary.

All documentation of Balance will be identified as 6-2.5-5.00-2.xxM-J

8.0 Balance Attachment

Balance Attachment Details

The balance shall have a male taper attachment at sting end. The taper shall have a gage length and diameter to be defined during design analysis and agreed to by AEDC congruent with the MC-96-B,C.

9.0 Additional Items

9.1 Carrying Cases

9.1.1 The balance case should provide for the safe handling and storage of the balance, and should be identified the balance stored inside.

10 Exceptions to the specifications shall be stated per item.