Comparison between experimental and theoretical results using Cuntze’s “failure mode concept” model for composites under triaxial loadings—Part B of the second world-wide failure exercise

Abstract

This paper represents a comparison between the predictions of Cuntze’s Failure Theory, referred to as ‘failure mode concept model, and experimental results provided in Part B of the second World-Wide Failure Exercise. The results covered 12 test cases, involving an isotropic matrix material, 7 UD laminas and 4 multi-directional laminates subjected to 3D states of stress. The UD lamina data, needed for the validation of the failure mode concept-based UD strength conditions, were broadly applicable, whereas the laminate data could only partly serve for model verification because some test cases show some discrepancies. Also, there was a lack of test data in some of the test cases and it is concluded that there is a need to obtain more representative test data. Nevertheless, a good mapping could be achieved by the applied strength conditions dedicated to the specific test case.

Failure of Fiber-Reinforced Composites

“…This yields the formulation of the failure criterion as quadratic-additive interaction criteria based on four of the five stress invariants given by the transversal isotropy. An alternative formulation for the interfiber failure criterion is given by Cuntze [30], who uses five stress invariants. Based on this formulation, as function of external loading, three independent interfiber failure modes for composites can occur as shown in Fig.…”

“…According to [41], the overall impression of the 3D failure theories provided by Pinho [49,50], Carrere [51,52], Puck [53,54], and Cuntze [30] were ranked best. However, many discussions have accompanied the "World-Wide Failure Exercise II" regarding the reliability of the experimental data provided.…”

“…However, many discussions have accompanied the "World-Wide Failure Exercise II" regarding the reliability of the experimental data provided. In particular, for those test cases dealing with 3D stress states many involved researchers commented on the experimental issues associated with the measurements [30,41,49,[54][55][56][57]. Beyond those failure theories compared in the "World-Wide Failure exercise" other groups also presented derivatives of existing theories or proposed essentially new theories [58,59].…”

“…As discussed by Bleier [190], Cuntze [30], Pinho [49,84], Deuschle [97], and Basan [191], there is a strong need to provide true material properties as input for modern failure criteria of fiber-reinforced composites. Juhasz points out that failure prediction generally should be possible without prior knowledge of the exact load configuration and according experimental test results of a specific structure [59].…”

The background to Part B of the Second World-Wide Failure Exercise: Evaluation of theories for predicting failure in polymer composite laminates under three-dimensional states of stress

“…(5) A permanent strain due to the micro-damage has been added. Cuntze, Refs [62,63] (1) Curve fitting of data in Test Cases 2-4 and 12.…”