Attachment A-22 RWO 1.docx

REPRESENTATIVE WORK ORDER (RWO) 1

SWO INFORMATION

WORK DESCRIPTION

Work Description:

Pursuant to the Provisions of the above Subcontract, the Subcontractor is authorized to proceed with the work as follows:

Statement of Work: See below for SOW.

* Please fill out this section only if you chose “Level of Effort” under Effort Type.

FINANCIAL SUMMARY

SIGNATURE BLOCKS

Introduction A spacecraft has a metallic honeycomb sandwich panel whose function is to support the four reaction wheels used for attitude control of the spacecraft during flight. This panel with reaction wheel support structure needs analysis performed to support the upcoming CDR and testing activities. The hardware is shown in the figure below. Three reaction wheels are supported on the top (one on each rectangular metallic frame) and one on the bottom (on metallic bipods).

Analysis Overview The task is to create a finite element model of the structure and perform all the piece part and assembly level stress analyses including the bolted and bonded joint analysis. Review and sign the piece part and assembly drawings. Prepare for and present at the CDR. Perform pre-test analysis for a static verification test including defining the test pulls and strain gage locations. Finally, perform the pre-test analysis for the random vibration test and provide all accelerometer predictions and locations to ensure hardware protection.

Perform the following Tasks

1. Perform piece part and assembly level stress analysis.

1.1. Create a finite element model for the support deck assembly. The model should accurately represent the load paths and pass basic model checks to ensure numeric well conditioning. If the finite element analysis is performed using a solver other than Nastran the contractor is responsible for ensuring the other solver results are within 2% of the Nastran results.

1.2. Perform stress analysis (using test factors of safety) for the piece parts using MAC loading of 20 g’s and the random vibration spec below. The random vibration environment is in three orthogonal axes, along the edges of the panel and normal to the panel.

1.3. Perform modal analysis to confirm the first mode of the assembly is greater than 35 Hz. Additionally, determine the first lateral (each axis) and normal modes.

1.4. Perform bolted joint analysis for the connections between all the piece parts using the loading defined in task 1.2.

1.5. Perform bonded joint analysis for the connections between all the piece parts using the loading defined in task 1.2.

1.6. Summarize margins and review with JPL.

2. Review and sign piece part assembly drawings.

2.1. Review all piece part drawings. Assume the following: 1 panel, 2 spools, 3 edge fittings, 1 bi-pod, 1 frame, 1 triangle totaling nine (9) piece part drawings.

2.2. Review all assembly drawings. Assume the following: reaction wheel frame (top frames with triangle), support deck (honeycomb panel with spools and edge fittings), full assembly (all pieces integrated) totaling three (3) assembly drawings.

3. Prepare for and present at the CDR.

3.1. Prepare charts to present at CDR. They should include a description of the finite element model including modeling assumptions, loading, materials with properties, analysis methodology, piece part margin tables, bolted and bonded joint margin tables.

3.2. Travel to JPL for 1 day to present at the review.

3.3. Assume 20% rework for actins coming out of the review.

4. Prepare for static test.

4.1. Define the assembly (panel and reaction wheel support structure) test configuration needed to achieve the test objective of structural verification.

4.2. Perform piece part and assembly level analysis on the test configuration under test loads. Determine strain gage placement for hardware protection and test verification. Develop a table of strain gage predictions and hardware capabilities.

4.3. Prepare charts to present at the Test Readiness Review (TRR)

4.4. Travel to JPL for 1 day to present at the review.

4.5. Travel to JPL for 3 days to be present for the test.

5. Prepare for the random vibration test.

5.1. Perform piece part and assembly level analysis on the test configuration for the random vibration environment defined in task 1.2.

5.2. Determine accelerometer locations to track critical areas to be identified, determine predictions for those accelerometers and capabilities for the hardware.

5.3. Prepare charts to present at the Test Readiness Review (TRR)

5.4. Travel to JPL for 1 day to present at the review.

5.5. Travel to JPL for 3 days to be present for the test.

6. Prepare a final report of all the analysis performed on this contract.

6.1. Prepare and submit a final report detailing all the analysis done to support the design and tests.

Deliverables The following are the deliverables from this contract:

1. A Nastran bulk data format finite element model of the Reaction Wheel Support Deck (Task 1)

2. Signed drawings or email concurrence of acceptance of the drawings. (Task 2)

3. Review charts to be presented at the CDR (Task 3) which include summarizing the results from Task 1.

4. Review charts to be presented at the static test readiness review (TRR) which include the results from Task 4.

5. CAD images showing accelerometer locations for random vibration test and a table of accelerometer predictions and capabilities (Task 5).

6. Review charts to be presented at the random vibration test readiness review (TRR) which include the results from Task 5.

7. A final stress report (Task 6) that address the following …

· Finite element model: assumptions, checkout results, constraints

· Loading: types of loading used in the analysis

· Piece Part Analysis; margin summaries of the piece parts considering MAC and random loading

· Assembly analysis: margin summaries of the bolted joint analysis considering MAC and random loading.

· Test analysis results.

Provided Information As part of this statement of work, JPL will provide the following items:

1. CAD model of Reaction Wheel Support Deck Assembly

JPL 7478 Rev 05/22 image1.png image2.png