SATPC0032028 Tab 04 SOW.pdf

TDEA Weldability Study: Induction Welding

SOW

Summary The Thermoplastics Development for Exploration Applications (TDEA) project seeks to understand through manufacturing, characterization, and test the trade-offs of different thermoplastic composite

(TPC) welding methods and the weldability of different candidate material systems. Toward this goal, TDEA planned a weldability study including resistance, conduction, ultrasonic, and induction welding of at least five material systems. This study is a precursor to TDEA applications that are spot welds of lap joints, and so the welding approaches are tailored to this configuration. However, in general, this study is focused on generic coupon configurations for broad applicability of the results to TDEA and other projects. The scope of work includes preparing flat substrates using unidirectional tape prepreg materials: welding the substrates into lap shear and double cantilever beam configurations, and inspection and test of the welded specimens. The evaluation of the welded joints that NASA plans includes microscopy, differential scanning calorimetry (DSC), ultrasonic inspection, and mechanical testing. Additional inspections and tests may be performed on the welded joints to investigate anomalies or as available. The key findings from this study shall be published via NASA Tech

Memorandum(s) or conference paper(s).

TDEA has initiated resistance and conduction welding efforts. This SOW describes the approach for TDEA to evaluate induction welds.

In this document, a requirement is identified by “shall,” a good practice by “should,” permission by

“may” or “can,” expectation by “will,” and descriptive material by “is.”

Objective Collect and evaluate data on the induction welding processes and resulting joint performance to support material and weld method selection.

Tasks and requirements

Test specimen configurations The subset of the weldability study test matrix with induction welding is listed in Table 1. The welding approach shall be tailored for relevance to TDEA’s applications, which require spot welds. For this reason, each specimen shall be welded individually. For both test configurations, 3 specimens

(designated as the process characterization specimens) shall be welded with temperature history recorded in the weld interface and outside of substrate. This specimen shall be used for nonmechanical destructive inspection and tests. The remaining specimens shall be welded with external temperature measurements for quality assurance (but without embedded sensors) and then will be subjected to mechanical tests.

The specimen configurations are:

• Single lap shear (SLS) following ASTM D5868, Figure 1. The nominal substrate layup is

[45/0/-45/90]2s (0 along loading direction) except for M30S/PEKK which for which the nominal layup is [45/0/-45/90]4s.

• Double cantilever beam (DCB) following ASTM D5528, Figure 2. The substrate layup is TBD and shall be determined based on discussions between NASA and the welding organization considering welding performance and the requirements for successful measurement of Mode I fracture toughness.

The specimens shall be welded individually to be representative of static spot weld applications and to assess reproducibility. The specimens shall be labeled as FIBER-MATRIX-TEST-NUMBER, for example, AS4-PEEK-SLS-01. Traceability between specimens and substrates shall be implemented and documented.

Table 1. Quantities of specimens to be welded and delivered to NASA.

Material system

Specimen count

SLS DCB

AS4/PEEK

(TC1200)

12 6

AS4/PEI

(Solvay)

12 6

T700/LM-PAEK

(TC1225)

12 6

AS4/PPS

(TC1100)

12 6

M30S/PEKK

(thin ply)

7 0

Totals 55 24

Figure 1. Single lap shear specimen dimensions (weld area shown as red dashed lines). Not to scale.

Figure 2. Double cantilever beam specimen dimensions (weld area shown as red dashed lines). Note, extending the weld more than 4 inches from the Kapton insert is optional. Not to scale.

Deliverables

1. Organize and participate in six meetings with NASA

a. Kickoff meeting

b. Substrate design meeting

c. Process development review

d. Inspection review

e. Test data review

f. Publication review

2. Provide requirements for substrate tailoring for induction welding processes.

a. Support up to 1 iteration with NASA to determine the layups for the specimens.

3. Develop and tune process for each material and specimen configuration.

a. Report final welding parameters for each configuration.

4. Weld specimens per the test matrix, Table 1.

a. Process characterization specimen (3 for each material, weld approach, and specimen configuration) shall include process history data for temperature, pressure, and power using methods proposed by the welding organization with concurrence from NASA.

b. Process data shall be reported for each weld and shall include temperature, pressure, and power as a function of time. Additional process data may be reported as deemed appropriate.

5. Inspect welds using standard practice as defined by the welding organization.

a. Identify and report inspection process and evaluation criteria.

b. Report inspection results and interpretation for each weld.

6. Ship specimens to NASA.

7. Support test results interpretation and publication.

a. Review, discuss, and interpret results.

b. Co-author 1 technical report or conference paper.

Government Furnished Equipment Substrates shall be provided for each material and weld configuration as described in Table 2. For each material, weld approach, and specimen configuration 3 extra pairs of substrates are provided to support process development (see task 3); these specimens do not need to be delivered to NASA. NASA may contract the panel manufacture and machining.

Table 2. Substrate counts for each material and weld method including 6 each for process development.

Material system Specimen substrates counts

Fiber/matrix Supper/identifier Resin content

Consolidated ply thick. (in)

SLS

(4 in. x 1 in.)

DCB

(10 in. x 1 in.)

AS4/PEEK Toray/TC1200 34 0.0055 30 18

AS4/PEI Solvay 32 0.0052 30 18

T700/LM-PAEK Toray/TC1225 34 0.0054 30 18

AS4/PPS Toray/TC1100 34 0.0083 30 18

M30S/PEKK Osaka 37 0.0014 20 6

Totals 140 78 GFE will be provided by date agreed to by contractor and NASA.

Schedule and deliverables The schedule refers to weeks after authority to proceed.

1. Week 1: Kick-off meeting (task 1a)

2. Week 1: Requirements for substrate tailoring for induction welding process (task 2)

3. Week 2: Substrate design meeting (task 1b), finalize panel designs

4. Week 10: Process development data delivered (task 3a) and process development review meeting (task 1c)

5. Week 14: Welds complete, process data delivered to NASA (task 4)

6. Week 15: Inspection complete (task 5), inspection review meeting (task 1d), and data delivered to NASA (task 5a and b)

7. Week 16: Welded specimens shipped (tasks 6)

8. Week 22: Test data review meeting (1e)

9. Weeks 22-30: Support publication preparation (task 7)

10. Week 30: Publication review meeting (1f)

Period of Performance 6/1/2023 – 3/7/2024

Travel / ODC Requirements None.

Technical POC Name / Code: Andrew Bergan / LARC-D309 Title: Senior Research Engineer Phone Number: 757-864-3744