Journal of Composites Technology & Research 

About: Journal of Composites Technology & Research is an academic journal. The journal publishes majorly in the area(s): Epoxy & Ultimate tensile strength. Over the lifetime, 549 publications have been published receiving 10324 citations.

Mechanics of Composite Materials: Past, Present, and Future

Abstract: Composite mechanics disciplines are presented and described at their various levels of sophistication and attendant scales of application. Correlation with experimental data is used as the prime discriminator between alternative methods and level of sophistication. Major emphasis is placed on (1) where composite mechanics has been; (2) what it has accomplished; (3) where it is headed, based on present research activities; and (4) at the risk of being presumptuous, where it should be headed. The discussion is developed using selected, but typical, examples of each composite mechanics discipline identifying degree of success, with respect to correlation with experimental data, and problems remaining. The discussion is centered about fiber/resin composites drawn mainly from the author's research activities and experience spanning two decades at National Aeronautics and Space Administration (NASA) Lewis Research Center.

Survey of Failure and Post-Failure Theories of Laminated Fiber-Renforced Composites

Abstract: This paper reviews the existing theories of failure of laminated fiber-reinforced composite materials. The failure theories of isotropic materials are also reviewed. There exist at least 30 failure theories for laminated composites. Some of these theories are applied directly to the laminate while the rest of the theories are applied to the individual layers of the laminate. In addition, the paper reviews the theories of the post-failure behavior of laminated composites, that is, the behavior of laminated composites beyond first ply failure. For this analysis there exist at least twelve theories, which are included in this survey.

Modeling Damage in a Plain Weave Fabric-Reinforced Composite Material

Abstract: A method for describing damage propagation in a woven fabric-reinforced composite material subjected to tension or shear loading is presented. A three-dimensional unit cell description of a plain weave graphite/epoxy fabric-reinforced composite was constructed. From this description, finite element models were generated. An incremental iterating finite element algorithm was developed to analyze loading response. This finite element program included capabilities to model nonlinear constitutive material behavior (anisotropic plasticity), and a scheme to estimate the effects of damage propagation by stiffness reduction. Tension and shear loadings were modeled. Results from the finite element analysis compared favorably with experimental data. Nonlinear shear stress-strain behavior of the fabric composite was shown to be principally caused by damage propagation rather than by plastic deformation of the matrix.

Micromechanical modeling of fiber/matrix interface effects in transversely loaded SiC/Ti-6-4 metal matrix composites

Abstract: The transverse tensile behavior of a composite composed of unidirectional silicon-carbide fiber (Textron SCS-6) in a Ti-6AL-4V matrix is examined with emphasis on the effects of fiber-matrix interface strength. The residual stresses as a result of a mismatch in the coefficients of thermal expansion of silicon carbide and titanium are estimated analytically and compared with measurements made using X-ray diffraction techniques. Idealizing the composite as a regular rectangular array of fibers in an elasto-plastic matrix, the transverse tensile stress-strain behavior is predicted under the assumptions of an infinitely strong interface as well as an interface without tensile strength. These results are compared with experiments conducted at three different temperatures. The agreement between experiment and predictions based on an interface without tensile strength is extremely close. The modeled stress-strain curves predict a well-defined knee in the transverse tensile stress-strain curve associated with the separation of fiber and matrix at their interface. The same stress-strain behavior is observed experimentally. Results of edge replica experiments and mechanical unloading from stress levels above the knee are also presented as additional evidence of the association of fiber-matrix separation with the knee in the transverse tensile stress-strain curve.

Delamination Growth and Thresholds in a Carbon/Epoxy Composite under Fatigue Loading

Abstract: This paper presents a study on delamination growth in Mode I, Mode II and mixed mode under fatigue loading in an HTA/6376C composite. The computed slopes of the modified Paris plots were high. Therefore, threshold values of the strain energy release rate for delamination growth were determined. Low fatigue threshold values revealed a significant effect of fatigue loading. The largest effect was found for the ENF test (Mode II) for which the fatigue threshold value was only 10% of the critical strain energy release rate in static tests. Threshold values for MMB (mixed mode) and DCB (Mode I) tests were 15% and 23% of the static values, respectively. Fractographic evaluation revealed identical initial failure mechanisms in fatigue and static loading conditions for the ENF specimen. The ENF specimen failed by formation and coalescence of microcracks. The low fatigue threshold for the ENF specimen was explained by microscopical observations on the specimen edge. It was also shown that the fracture surfaces generated in static and fatigue DCB and MMB tests were similar.