Progressive Failure Behaviors of 2D Woven Composites

Abstract

This paper focuses on understanding the progressive failure behavior of woven composites. Five weaves, i.e. plain, 4-, 5-, 8-harness satin and twill, are considered. Rather than developing a new progressive failure analysis approach, the focus is placed on comparing the damage behaviors of the various weaves predicted by the selected failure criterion and property degradation model. The loading conditions include uniaxial tension and compression. The discussions focus on (1) the effect of the woven architecture on the predicted progressive failure behaviors (2) the similarities and difference in the damage initiation and evolution mechanisms between the plain and satin weaves and (3) the sensitivity of the predicted progressive failure behavior to assumptions about geometric nonlinearity and the property degradation model. The results have shown that the weave architecture (i.e. weave pattern) has significant effects on the predicted progressive failure behaviors even if the composites have the same overall fiber volume fraction, tow waviness and tow cross-section. Comparisons of the damage initiation and evolution mechanisms in the plain and 4-harness satin weaves indicate significant similarities in the damage behaviors in the comparable regions for the two weaves. The results also show that the predicted response of low waviness composite, which is more commonly seen in most structural applications, is quite insensitive to the assumed property degradation model. This imposes difficulties in validating a model by comparison with test results for low waviness composites.

Acoustic Emission from Microcrack Initiation in Polymer Matrix Composites in Short Beam Shear Test

“…Dominant frequencies (FmA) appeared in rather narrow range of 230 to 260 kHz typical for interphase phenomena, and debonding defects ( Fig. 7b) were observed in shear mid-plane near fiber free ends, in agreement with the model proposed by Tang and Whitcomb [39].…”

“…5a) or at the tow/matrix interface. They confirmed the suggestion of an analytical model, indicating that debonding microcracks may appear near fiber discontinuities within the tow [39]. In samples failed but not destroyed in the test, the SEM observations revealed the presence of debonding defects between and inside fiber tows (Fig.…”

Strength Prediction of Composite Materials from Nano- to Macro-scale

“…The most significant finding is the large deviation in the predicted maximum load between the sudden degradation concepts and the damage mechanics concept. The deviation between the prediction of (Tang & Whitcomb, 2003) and the present prediction taken with m =0.001 is attributed to the different failure criteria used. In the case of the damage mechanics concept, the use of m =8 led to a more degraded behavior of the material compared to m =2 especially at large strains.…”

“…The geometry of the RVE, taken from (Tang & Whitcomb, 2003) to enable comparison, was created using the software package WiseTex (Verpoest & Lomov, 2005) which possess specific capabilities in the creation of the micro-geometry of textile composite materials. The software requires as input the number of fill and warp tows, the crimp function and the geometry of the cross-sectional area of the tows.…”

“…Fig.11 compares the predicted tensile stress-strain curves for the cases of m =0.001, m =2 and m =8 with the curve predicted by (Tang and Whitcomb, 2003) using the maximum stress failure criterion and sudden material property degradation rules. The different degradation concepts are explained in Fig.12 by means of the resulted tensile stress-strain curves.…”