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  • 1
    facet.materialart.
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    Strain rate characterization of unidirectional graphite/epoxy composite (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: For an investigation of problems of composites at high strain rates with dominant wave propagation effects, such as dynamically loaded composite jet engine blades, the longitudinal, transverse, and in-plane shear properties of unidirectional SP 288/AS graphite/epoxy were measured at various strain rates ranging from quasi-static to over 500/s. The test specimens were rings 10.16 cm in diameter, 2.54 cm long, 6 to 8 plies thick, and with fibers at 0, 90, and 10 deg off-axis. Quasi-static testing was conducted in a fixture which applies hydraulic pressure to the ring specimens, and dynamic testing was conducted by applying an internal pressure pulse through a liquid in a special fixture. Dynamic stress-strain curves are presented. For the 0-deg specimens, the modulus increases with strain up to 20 percent of the static value. The modulus and strength increase sharply in the 90-deg rings with strain rate reaching values two to three times the corresponding static rate.
    Keywords: COMPOSITE MATERIALS
    Format: text
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  • 2
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    Fire test methodology for aerospace materials. 1: Thermal and smoke toxicological assessments of graphite/bismaleimide and graphite/epoxy systems (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Both materials possess a high degree of thermal stability, with total heat release values being essentially identical under piloted ignition conditions over a range of 5 to 10 W/sq cm incident heat flux. The graphite/epoxy material had a tendency to auto-ignite at a lower heat flux (about 7 W/sq cm) and produced about 23 percent higher peak heat release rates, approximately 42 percent more carbon monoxide and considerably more smoke than the graphite/bismaleimide under conditions of piloted ignition. Toxicological potencies of smoke produced from the two composites were equivalent for 30 minute exposures. Potencies were also comparable to many common materials, such as wood. There was no evidence for the formation of an "unusual toxicant" nor for any short term post-exposure toxicological effects.
    Keywords: COMPOSITE MATERIALS
    Type: NASA-CR-166196 , SWRI-03-5565-001
    Format: application/pdf
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  • 3
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    Cork-resin ablative insulation for complex surfaces and method for applying the same (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A method of applying cork-resin ablative insulation material to complex curved surfaces is disclosed. The material is prepared by mixing finely divided cork with a B-stage curable thermosetting resin, forming the resulting mixture into a block, B-stage curing the resin-containing block, and slicing the block into sheets. The B-stage cured sheet is shaped to conform to the surface being insulated, and further curing is then performed. Curing of the resins only to B-stage before shaping enables application of sheet material to complex curved surfaces and avoids limitations and disadvantages presented in handling of fully cured sheet material.
    Keywords: COMPOSITE MATERIALS
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  • 4
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    Observation of damage growth in compressively loaded laminates (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Graphite/epoxy laminates have a definite advantage with respect to the strength-to-weight relation over many standard engineering materials used in aerospace applications. However, this advantage is somewhat reduced by the sensitivity of these laminates to operational hazards, which include a low-velocity impact by foreign objects. Investigations conducted by Chai (1982) and Knauss et al. (1980) have been concerned with the growth of impact damage in compressively loaded laminates, and the visualization of such an impact damage. The present study represents a condensation of parts of these investigations, taking into account a determination of the damage-growth mechanism via real-time recording of the impact event. The material considered, a T300/5208 graphite/epoxy laminate, is typical of the configuration proposed for future heavily loaded primary structures. It has stiffness properties similar to those of the wing skins in existing transport aircraft.
    Keywords: COMPOSITE MATERIALS
    Type: Experimental Mechanics (ISSN 0014-4851); 23; Sept
    Format: text
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  • 5
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    Results of tests of K5NA and a revised formulation of EPDM/cork patch material in MSFC Hot Gas Facility (1982)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: During prelaunch procedures at Kennedy Space Center some of the EPDM Thermal Protection System material was damaged on the Solid Rocket Booster stiffener stubs. The preferred solution was to patch the damaged areas with a cork-filled epoxy patching compound. Before this was done, however, it was requested that this patching technique be checked out by testing it in the MSFC Hot Gas Facility. Two tests were run in the HFG in 1980. The results showed the patch material to be adequate. Since that time, the formulation of the cork-filled epoxy material has been changed. It became necessary to retest this concept to be sure that the new material is as good as or better than the original material. In addition to the revised formulation material, tests were also made using K5NA as the patch material. The objectives of the tests reported herein were to: (1) compare the thermal performance of the original and the new cork-filled epoxy formulations, and (2) compare the K5NA closeout material to these epoxy materials. Material specifications are also discussed.
    Keywords: COMPOSITE MATERIALS
    Type: NASA-CR-170890 , NAS 1.26:170890 , LMSC-HREC-TN-D867570
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  • 6
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    Results of tests of weathered K5NA closeout material in the MSFC Hot Gas Facility (1982)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The application of K5NA over hypolon was investigated. The effects of using K5NA over painted cork surfaces, the effects of weathering on the unpainted K5NA surfaces are determined, and the use of water versus solvent for tooling K5NA in place were compared. It is concluded that: (1) K5NA can be applied to hypalon surfaces; (2) K5NA can be left unpainted; and (3) K5NA can be tested with water or solvent.
    Keywords: COMPOSITE MATERIALS
    Type: NASA-CR-170893 , NAS 1.26:170893 , LMSC-HREC-TN-D867576
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  • 7
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    Results of variable enthalpy tests of CPR-488 TIP panels in MSFC Hot Gas Facility (1982)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Tests were conducted to determine the effects of variable enthalpy levels on CPR-488 foam performance and/or recession. Also to be determined was whether the BX-250 thickness indicator plugs (TIP) concept is feasible for measuring recession rates of CPR-488 foam during external tank flight. The tests determined that the TIP plug idea works. The accuracy of the indicated recession depth is approximately + or - 1.16 in. The BX-250 plugs with TiO2 work better than the regular BX-250 plugs. Also, there is an effect of enthalpy on CPR-488 foam performance.
    Keywords: COMPOSITE MATERIALS
    Type: NASA-CR-170889 , NAS 1.26:170889 , LMSC-HREC-TM-D784773
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  • 8
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    Effect of stress concentrations in composite structures (1984)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The goal of achieving a better understanding of the failure of complex composite structure is sought. This type of structure requires a thorough understanding of the behavior under load both on a macro and micro scale if failure mechanisms are to be understood. The two problems being studied are the failure at a panel/stiffener interface and a generic problem of failure at a stress concentration.
    Keywords: COMPOSITE MATERIALS
    Type: NASA-CR-173976 , NAS 1.26:173976 , SM-8417
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  • 9
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    Failure analysis of composite laminates including biaxial compression (1983)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This report describes a continued effort on the development and application of the tensor polynomial failure criterion for composite laminate analysis. In particular, emphasis is given to the design, construction and testing of a cross-beam laminate configuration to obtain "pure' biaxial compression failure. The purpose of this test case was to provide to permit "closure' of the cubic form of the failure surface in the 1-2 compression-compression quadrant. This resulted in a revised set of interaction strength parameters and the construction of a failure surface which can be used with confidence for strength predictions, assuming a plane stress state exists. Furthermore, the problem of complex conjugate roots which can occur in some failure regions is addressed and an "engineering' interpretation is provided. Results are presented illustrating this behavior and the methodology for overcoming this problem is discussed.
    Keywords: COMPOSITE MATERIALS
    Type: NASA-CR-172192 , NAS 1.26:172192
    Format: application/pdf
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  • 10
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    Development of failure criterion for Kevlar-epoxy fabric laminates (1984)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The development of the tensor polynomial failure criterion for composite laminate analysis is discussed. In particular, emphasis is given to the fabrication and testing of Kevlar-49 fabric (Style 285)/Narmco 5208 Epoxy. The quadratic-failure criterion with F(12)=0 provides accurate estimates of failure stresses for the Kevlar/Epoxy investigated. The cubic failure criterion was re-cast into an operationally easier form, providing the engineer with design curves that can be applied to laminates fabricated from unidirectional prepregs. In the form presented no interaction strength tests are required, although recourse to the quadratic model and the principal strength parameters is necessary. However, insufficient test data exists at present to generalize this approach for all undirectional prepregs and its use must be restricted to the generic materials investigated to-date.
    Keywords: COMPOSITE MATERIALS
    Type: NASA-CR-172465 , NAS 1.26:172465
    Format: application/pdf
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