CMS_TO1_Reqts_-_Final_10-31-18.pdf

Exploration Extra-Vehicular Mobility Unit (xEMU) Composite Manufacturing Services

Sample Task Order 1: Composite Hard Upper Torso, Manufacturing

Prototype Requirements

1.1 Functional Requirements

1.1.1 The HUT/Hatch shall have a total leakage of less than 50 standard cubic centimeters per minute (sccm) with a 4.3 psig pressure load using air.

Rationale: This HUT/Hatch design has been proven to meet this requirement when fabricated previously. The intent is that the contractor proves by design that the deflection is limited in sealing locations to maintain good seal squeeze, there is limited leakage through the structure, and sealing surface, surface roughness can be controlled.

1.1.2 The HUT/Hatch mass shall be less than 25 lbs combined.

Rationale: Reducing mass enables the design to be extensible to the future.

1.2 Interface Requirements

1.2.1 The HUT/Hatch shall include a neck ring interface as specified in the HUT model.

Rationale: The placement and interface of the helmet on the HUT/Hatch is critical for appropriate interface and function of the helmet. The method to include the fastener interface can be modified.

1.2.2 The HUT/Hatch shall include scye bearing interfaces as specified in the model. The location and orientation of the scye bearing interface cannot be changed.

Rationale: The placement and interface of the shoulders on the HUT/Hatch is critical for appropriate interface and function of the shoulder joint.

1.2.3 The HUT/Hatch shall include a PLSS pad interface as specified in the model. The location and orientation of the PLSS pad interface cannot be changed.

Rationale: The placement and interface of the PLSS pad on the HUT/Hatch is critical for appropriate interface with the PLSS.

1.2.4 The HUT/Hatch shall include a Display and Control Unit (DCU) pad interface as specified in the model. The location and orientation of the DCU pad interface cannot be changed.

Rationale: The placement and interface of the DCU pad on the HUT/Hatch is critical for appropriate interface with the DCU.

1.2.5 The HUT/Hatch shall include a Hatch Latch Mechanism interface as specified in the model. The location and orientation of the Hatch Latch mechanism interface cannot be changed.

Rationale: The placement and interface of the hatch latch interfaces on the HUT/Hatch has been tested and is critical for proper functionality.

1.2.6 The HUT/Hatch shall include an interface for a Negative Pressure Relief Valve (NPRV), Positive Pressure Relief Valve (PPRV), Auxiliary PPRV and low flow purge valve in the approximate locations indicated in the HUT model.

Rationale: The interface for the NPRV, PPRV, Aux PPRV, and purge valve on the HUT/Hatch is critical for proper functionality. The location of these features can be slightly modified to improve manufacturability.

1.2.7 4.2.7 The HUT/Hatch shall include an interface for a communication connector interface (PN: MS27477Y12E35P) in the approximate locations indicated in the model.

Rationale: The interface for the communication connector on the HUT/Hatch is critical for proper functionality. The location of this feature can be slightly modified to improve manufacturability.

1.2.8 The HUT/Hatch shall include internal interfaces for hatch cover as indicated in the model. The location and orientation of the hatch cover interface cannot be changed.

Rationale: The interface and location for the hatch cover and water and ventilation lines in the HUT/Hatch is critical for proper functionality.

1.2.9 The HUT/Hatch shall include a body seal closure (BSC) interface as specified in the HUT model.

Rationale: The placement and interface of the body seal closure on the HUT/Hatch is critical for appropriate interface and function of the BSC. The method to include the fastener interface can be modified.

1.3 Structural Requirements

1.3.1 The HUT/Hatch shall have a Maximum Operating Pressure of 10.6 pounds per square inch delta (psid).

Rationale: The advanced suit is being developed to operate at 8.3 psid. The pressure stated allows for pressure rise before the relief valve is activated.

1.3.2 The HUT/Hatch shall have a Proof pressure of 15.9 psid.

Rationale: The advanced suit is being developed to operate at 8.3 psid. The manufacturing prototype should be pressurize-able to the proof pressure for validation. NASA will verify this contract.

1.3.3 The HUT/Hatch shall meet manload requirements (as listed) with an operating pressure of 8.3 psid (57.2 kilopascals delta (kPad)) operations.

• Waist 1014 lbs (Externally induced, evenly distributed over whole interface)

• Arm 382 lbs (Externally induced, in the upward position); or 293 lbs

(isometric, normal to the opening)

Rationale: The advanced suit is being developed to withstand the manloads historically identified for the EMU system. Verification of this requirement should be done via validated analysis.

1.3.4 The HUT DCU interface shall withstand a DCU weight (30 lbs) and externally induced load (50 lbs) combination in any direction.

Rationale: The advanced suit is being developed to operate in the NBL environment with a weighted DCU (~30 lbs). In addition to the DCU simulator mass, the DCU may undergo handling loads up to 50 lbs. Verification of this requirement can be done via validated analysis.

1.3.5 The neck ring interface shall withstand a load of 400 lbs in the vertical up direction, while pressurized to 8.3 psid.

Rationale: There will be an unmanned handling aide attached to the neck ring interface. The FOS requirements apply to all load cases. Verification of this requirement can be done via validated analysis.

1.3.6 The HUT/Hatch PLSS Pad and PLSS Hitch interface shall suspend the total system mass of 600 lbs, when the suit is hanging in an orientation from heads up to 150 degrees rotated heads down.

Rationale: The maximum weight of the system is expected to be 600 lbs. However, the analysis shall include is a dynamic load factor of 2. ARGOS system includes load limiting straps that will reduce the load to <1160 lbs. The FOS requirements apply to all load cases. Verification of this requirement should be done via validated analysis.

1.3.7 The HUT/Hatch shall maintain a minimum factor of safety of 1.5 against yielding and 2.0 against ultimate failure for all loading cases.

Rationale: Spacesuit historical factors of safety.

1.3.8 The xEMU should not fail catastrophically following impact with a 2 inch diameter steel ball when manned, pressurized to 8.3 psid, in microgravity, translating at 2 ft/s, and in the heaviest EVA configuration.

Rationale: It is assumed that the mass analyzed is only the rigidly attached mass. This assumption includes a conservative estimate of 1/2 suit weight (150/2= 75 lbs), PLSS/DCU (190 lbs), and tools (30 lbs). Impact rigid system mass totals = 295 lbs.

Catastrophic failure is defined as leakage beyond what the suit life support system can feed, 5.6 pph O2 at 4.3 psia.

Per NASA-STD-5019, verification of fracture control should be done by demonstrating damage tolerance at the coupon and full scale testing of the manufacturing prototype. The contractor will evaluate coupon level samples and NASA will test the manufacturing prototype for impact robustness.

At the design review, the contractor shall show by analysis that the HUT design will meet this requirement.

1.3.9 The xEMU should not fail catastrophically following impact with a 2 inch diameter steel ball when manned, pressurized to 8.3 psid, in lunar gravity, translating at 4 mph, and in the heaviest EVA configuration.

Rationale: It is assumed that the mass analyzed is only rigidly attached mass. This assumption includes approximately 1/2 suit weight, PLSS, DCU, and tools. Impact rigid system mass totals = 295 lbs. Impact region is limited to the upper torso, and does not include the hatch.

Catastrophic failure is defined as leakage beyond what the suit life support system can feed.

Evaluation of this requirement can be done by impact model and coupon level testing. At the design review, the contractor shall show by analysis that the HUT design will meet this requirement.

1.3.10 The xEMU shall be able to support life cycle testing, with a scatter factor of 4X, with a largest undetectable worst-case credible manufacturing flaw.

Rationale: There will be some imperfections in the composite structure. To support this requirement it is expected that the contractor determine the largest undetectable flaw and the worst location for a flaw to exist. Then via analysis the flaw is analyzed for cycle based failure.

1.4 Other Requirements

1.4.1 Corrosion potential between dissimilar metals or other corrosive materials for exposure to the NBL environment shall be mitigated.

Rationale: The hardware must be designed to operate without corrosion in the NBL. Evaluate the use of anodize and primers, or alternate approved methods.

1.4.2 Any area that is wetted with internal water flow shall have a galvanic potential within

0.25 mV with Titanium or sealed.

Rationale: The portable life support system thermal loop is primarily composed of titanium, and any wetted materials should be compatible.

1.4.3 The mechanical fasteners and features in the HUT/Hatch for structural integrity should not rely solely on bond strength.

Rationale: It is not desirable to rely on bond line strength and integrity for structural strength, mechanical interference is strongly preferred. Any fasteners that are bonded in the structure will need to have their integration process validated.

1.4.4 The HUT/Hatch system shall function appropriately with temperature ranges from 135° F to -170.7° F.

Rationale: The temperature range listed is a very conservative estimate of temperature exposure, based on Orthofabric sink temperatures during Shuttle EVAs (ESCG-4470-12-TEAN-DOC-0085). It is expected that the composite structure would be much closer to the internal vent temperature as a result of the MLI, but without an accurate thermal model for the thermal protection and the extremes on the lunar surface, the ranges are considered conservative. Material performance at temperature extremes is a consideration, but we expect to be able to tune thermal protection to some degree. Upper limit is based Tsink on latest Gateway mission style thermal analysis.