Z.M. Huang/ Composites Science and Technology 64(2004)529-548 mined, as illustrated in Ref [1]. Those data can be clas- laminae subjected to different kinds of uniaxial loads sified into two groups(see Ref. [ID. The first group is (longitudinal tension, transverse tension, longitudinal the constituent fiber and resin properties and the second compression, transverse com mpression, and in-plane group is the laminate geometric parameters. In the pre- shearing) up to failure, i.e. the ultimate uniaxial loads dictions made in Ref. [1], all of the fiber materials wer The retrieval of the constituent strengths was accom considered as linearly elastic until rupture for which plished in such a way that when all the ultimate uniaxial only elastic and ultimate properties are required, loads had been applied to the individual UD lamina whereas the resins were regarded as elastic-plastic respectively, the comparative maximum tensile and materials. Thus, the material properties consisted of the compressive stresses generated in the fiber and the resin fiber and resin elastic constants, the resin plastic materials were taken as their respective tensile and parameters, and the tensile and compressive strengths of compressive strengths. For example, when the ultimate the fibers(along longitudinal direction) and the resins. longitudinal tension, transverse tension, and the in The second group data, i.e. the laminate geometric plane shearing were applied to the UD lamina respec- parameters, included the laminate lay-up arrangements, tively, the resin material would generate three different laying angles, and thickness of each lamina in the lami- maximum tensile stresses. The resin tensile strength was nates. While the second group data can be obtained defined as the largest of these three tensile stresses from the condition as-fabricated (in the predictions in has been found that the tensile strengths of both the Ref [1], those provided by the organizers were directly fibers and the resins were determined against the ulti employed), the first group data have to be prepared with mate longitudinal tension of the UD laminae. The fiber more care In Ref [I], the elastic properties of both the and the resin compressive strengths were obtained based fibers and the resins for all of the 14 problems were on the ultimate longitudinal and transverse compres taken exactly the same as those provided by the organi sions of the UD laminae, respectively. More details are zers [3], whereas the remaining constituent properties provided in Ref [1] were retrieved from the responses of the individual Ud The theoretical results taken from Ref. [1] are re- laminae. The resin plastic parameters were back calcu- plotted in curves designated as"theory with thermal lated against the stress-strain responses of the corres- residual stresses"in Figs. 1-14 for all of the 14 exercise ponding laminae subjected to in plane shearing up to problems, respectively, which are compared with the failure. Having determined the fiber elastic and the resin test results provided by the exercise organizers [4]. It is elastic-plastic parameters, the constituent strength data seen that except for the problems 3, 4, 6, and 8, the were retrieved against the ultimate strengths of the UD correlations between the theory and the experiments for heory(final failure, with thermal residual stresses o Test results Theory(final failure, with thermal residual stresses) y-directional stress(MPa) Fig 1. Measured and predicted biaxial failure stresses for 0 lamina subjected to combined yy and txy Material type: E-Glass/LY556/HT907/ DY063mined, as illustrated in Ref. [1]. Those data can be clas￾sified into two groups (see Ref. [1]). The first group is the constituent fiber and resin properties and the second group is the laminate geometric parameters. In the pre￾dictions made in Ref. [1], all of the fiber materials were considered as linearlyelastic until rupture for which onlyelastic and ultimate properties are required, whereas the resins were regarded as elastic–plastic materials. Thus, the material properties consisted of the fiber and resin elastic constants, the resin plastic parameters, and the tensile and compressive strengths of the fibers (along longitudinal direction) and the resins. The second group data, i.e. the laminate geometric parameters, included the laminate lay-up arrangements, laying angles, and thickness of each lamina in the lami￾nates. While the second group data can be obtained from the condition as-fabricated (in the predictions in Ref. [1], those provided bythe organizers were directly employed), the first group data have to be prepared with more care. In Ref. [1], the elastic properties of both the fibers and the resins for all of the 14 problems were taken exactlythe same as those provided bythe organi￾zers [3], whereas the remaining constituent properties were retrieved from the responses of the individual UD laminae. The resin plastic parameters were back calcu￾lated against the stress-strain responses of the corres￾ponding laminae subjected to in plane shearing up to failure. Having determined the fiber elastic and the resin elastic–plastic parameters, the constituent strength data were retrieved against the ultimate strengths of the UD laminae subjected to different kinds of uniaxial loads (longitudinal tension, transverse tension, longitudinal compression, transverse compression, and in-plane shearing) up to failure, i.e. the ultimate uniaxial loads. The retrieval of the constituent strengths was accom￾plished in such a waythat when all the ultimate uniaxial loads had been applied to the individual UD lamina respectively, the comparative maximum tensile and compressive stresses generated in the fiber and the resin materials were taken as their respective tensile and compressive strengths. For example, when the ultimate longitudinal tension, transverse tension, and the in￾plane shearing were applied to the UD lamina respec￾tively, the resin material would generate three different maximum tensile stresses. The resin tensile strength was defined as the largest of these three tensile stresses. It has been found that the tensile strengths of both the fibers and the resins were determined against the ulti￾mate longitudinal tension of the UD laminae. The fiber and the resin compressive strengths were obtained based on the ultimate longitudinal and transverse compres￾sions of the UD laminae, respectively. More details are provided in Ref. [1]. The theoretical results taken from Ref. [1] are re￾plotted in curves designated as ‘‘theorywith thermal residual stresses’’ in Figs. 1–14 for all of the 14 exercise problems, respectively, which are compared with the test results provided bythe exercise organizers [4]. It is seen that except for the problems 3, 4, 6, and 8, the correlations between the theoryand the experiments for Fig. 1. Measured and predicted biaxial failure stresses for 0
lamina subjected to combined
yy and xy. Material type: E-Glass/LY556/HT907/ DY063. 530 Z.-M. Huang / Composites Science and Technology 64 (2004) 529–548