Engineering topics

Cushman, J. B.

Publications and source records attributed to Cushman, J. B..

10 records

NASA NTRS1985

Evaluation of a high temperature adhesive for fabricating graphite/PMR-15 polyimide structures

Tests are conducted to measure shear strength, shear modulus and flatwise tensile strength of the A7F (amide-imide modified LARC-13) adhesive system. An investigation is also conducted to determine the effect of geometric material parameters, and elevated temperature on the static strength of standard joints. Single-lap and double-lap composite joints, and single, double and step lap composite to metal joints are characterized. A series of advanced joints consisting of preformed adherends, adherends with scalloped edges and joints with hybrid interface plies are tested and compared to baseline single and double-lap designs.

Hill, S. G.↗

NASA NTRS1985

Bonded and Bolted Graphite/Polyimide Composite Joints

Four types of high-temperature joints designed for control surfaces. Design, analysis, and testing performed to develop four types of graphite/polyimide bonded and bolted composite joints for lightly loaded control surfaces on advanced transportation systems that operate at temperatures up to 550 degrees F (288 degrees C).

Skoumal, D. E.↗

NASA NTRS1985

Efficient Joints for Graphite/Epoxy Structures

Bonded joints perform well through wide temperature range. Tests indicate significant improvement in joint efficients available through geometric modifications and hybrid material additions at adherent interfaces. Material modifications consisted of placing S-glass polyimide fabric in joint between adherents. Most fabric interface specimens delaminated between two fabric plies as opposed to failing in base adherents.

Skoumal, D. E.↗

NASA NTRS1983

Design, fabrication and test of graphite/polymide composite joints and attachments: Summary

The design, analysis and testing performed to develop four types of graphite/polyimide (Gr/PI) bonded and bolted composite joints for lightly loaded control surfaces on advanced space transportation systems that operate at temperatures up to 561K (550 F) are summarized. Material properties and 'small specimen' tests were conducted to establish design data and to evaluate specific design details. 'Static discriminator' tests were conducted on preliminary designs to verify structural adequacy. Scaled up specimens of the final joint designs, representative of production size requirements, were subjected to a series of static and fatigue tests to evaluate joint strength. Effects of environmental conditioning were determined by testing aged (125 hours 589K (600 F)) and thermal cycled (116K to 589K (-250 F to 600 F), 125 times) specimens. It is concluded Gr/PI joints can be designed and fabricated to carry the specified loads. Test results also indicate a possible resin loss or degradation of laminates after exposure to 589K (600 F) for 125 hours.

Cushman, J. B.↗

NASA NTRS1983

Test and analysis of Celion 3000/PMR-15, graphite/polyimide bonded composite joints: Summary

Standard single lap, double lap and symmetric step lap bonded joints of Celion 3000/PMR-15 graphite/polyimide composite were evaluated. Composite to composite and composite to titanium joints were tested at 116K (-250 F), 294K (70 F) and 561K (550 F). Joint parameters evaluated were lap length, adherend thickness, adherend axial stiffness, lamina stacking sequence and adherend tapering. Tests of advanced joint concepts were also conducted to establish the change in performance of preformed adherends, scalloped adherends and hybrid systems. Special tests were conducted to establish material properties of the high temperature adhesive, designated A7F, used for bonding. Most of the bonded joint tests resulted in interlaminar shear or peel failures of the composite. There were very few adhesive failures. Average test results agree with expected performance trends for the various test parameters. Results of finite element analyses and of test/analysis correlations are also presented.

Cushman, J. B.↗

NASA NTRS1982

Design, fabrication and test of graphite/polyimide composite joints and attachments

The design, analysis, and testing performed to develop four types of graphite/polyimide (Gr/PI) bonded and bolted composite joints for lightly loaded control surfaces on advanced space transportation systems that operate at temperatures up to 561 K (550 F) are summarized. Material properties and small specimen tests were conducted to establish design data and to evaluate specific design details. Static discriminator tests were conducted on preliminary designs to verify structural adequacy. Scaled up specimens of the final joint designs, representative of production size requirements, were subjected to a series of static and fatigue tests to evaluate joint strength. Effects of environmental conditioning were determined by testing aged (125 hours at 589 K (600 F)) and thermal cycled (116 K to 589 K (-250 F to 600 F), 125 times) specimens. It is concluded Gr/PI joints can be designed and fabricated to carry the specified loads. Test results also indicate a possible resin loss or degradation of laminates after exposure to 589 K (600 F) for 125 hours.

Cushman, J. B.↗

NASA NTRS1982

Test and analysis of Celion 3000/PMR-15, graphite/polyimide bonded composite joints: Data report

Standard single lap, double lap and symmetric step lap bonded joints of Celion 3000/PMR-15 graphite/polyimide composite were evaluated. Composite to composite and composite to titanium joints were tested at 116 K (-250 F), 294 K (70 F) and 561 K (550 F). Joint parameters evaluated are lap length, adherend thickness, adherend axial stiffness, lamina stacking sequence and adherend tapering. Advanced joint concepts were examined to establish the change in performance of preformed adherends, scalloped adherends and hybrid systems. The material properties of the high temperature adhesive, designated A7F, used for bonding were established. The bonded joint tests resulted in interlaminar shear or peel failures of the composite and there were very few adhesive failures. Average test results agree with expected performance trends for the various test parameters. Results of finite element analyses and of test/analysis correlations are also presented.

Cushman, J. B.↗

NASA NTRS1982

Design Allowables Test Program, Celion 3000/PMR-15 and Celion 6000/PMR-15, Graphite/Polyimide Composites

A design allowables test program was conducted on Celion 3000/PRM-15 and Celion 6000/PMR-15 graphite/polyimide composite to establish material performance over a 116 K (-250 F) to 589 K (600 F) temperature range. Effects of aging, thermal cycling and moisture were also evaluated. Tension, compression and in plane shear properties were determined for uniaxial, pseudoisotropic and +45 laminates. Test results show sufficient strength and stiffness to substantiate graphite/polyimide composites as an acceptable structural material for high temperature structural applications.

Cushman, J. B.↗

NASA NTRS1982

High temperature composites for advanced missile and space transportation systems

A study has been conducted to characterize a state-of-the-art graphite/polyimide composite system by determining mechanical and thermophysical properties of selected laminates over a temperature range of -250 F to 600 F. The material studied was Celion 3000/PMR-15. Material property data obtained from testing included tension, compression and shear strengths, and coefficient of thermal expansion. Environmental conditions examined were: as cured/post-cured, isothermal aged at 600 F, thermal cycled from -250 F to 600 F, and moisture conditioned. This study has provided an initial data base on a graphite/polyimide composite system capable of operating in 500/600 F applications.

Mccleskey, S. F.↗

NASA NTRS1981

Design, Fabrication and Test of Graphite/Polyimide Composite Joints and Attachments for Advanced Aerospace Vehicles

Standard and advanced bonded joint concepts were evaluated to develop a data base for the design and analysis of advanced composite joints for use at elevated temperatures (561K (550F)). Design concepts for specific joint applications and the fundamental parameters controlling the static strength characteristics of such joints were identified. Test results are presented for rail shear and sandwich beam compression tests and tension tests of moisture conditioned specimens and bonded on "T" sections. Coefficients of thermal expansion data are presented for A7F (LARC 13 Amide-imide modified) adhesion. Static discriminator test results for type 1 and type 2 bonded and bolted preliminary attachment concepts are presented and discussed.

Cushman, J. B.↗