摘要
由于复合材料具体构造的复杂性,各种预测复合材料弹性常数的微观力学模型都难以确切模拟复合材料的几何构造、组份的物理状态及其真实的受力和变形情况。因而对既定模型的严格分析和数学推导不一定都能得到精确的预测。本文根据单向纤维复合材料中纤维分布的不均匀性,采用两级模型,简便地导得预测E_T(E_2)、G_(LT)(G_(12))的理论表达式,收集不同复合材料的多组试验数据进行检验结果表明本文方法与其他八种预测公式相比,具有较高的精度。尤其是对G_(LT)这个通常认为很难预测的剪切模量,本文方法似乎远优于其他公式。其中的机理还不能说得很清楚。
Owing to the complexity of the construction in CM, it is difficult to simulate precisely the geometry, physical state, and the actual loading condition and deformation state of each constituent in CM with various models of the micromechanics. Therefore, even if the established model is analysed and derived strictly, the accurate prediction may not be ensured.In this paper, related to the nonuniform distribution of the fibers in an unidirectional fiber composite, the formulas (Eq.4 and Eq.5, or their unified expression, Eq.6) for calculating the transverse modulus ET (E2) and shear modulus GLT(G12)were derived simply by a TWO-STEP MODEL, which composed of closely arranged fibers with matrix between them (as shown in Fig 1 and Fig 2.)Formulas obtained from the TWO-STEP MODEL have been checked by using eight sets of experimental data collected from references. Those experiments wera performed on different CM. The mean deviation,was used to evaluate the accuracy of various models. It is shown that, the TWO-STEP MODEL, as compared with other eight models, provide the most preferable predictions, especially good for the prediction of shear modulus GLT, which usually is difficult to predict. However the TWO-STEP MODEL is still not as satisfactory as expected. It may be caused by the anisotropic character of fibers, which for some kinds of fibers, such as CF, BF. is apparent. This paper, just as other papers, has not yet involved that character.As a compensation, it was proposed in this paper to modifying Vf in Eq.4. for C/EP and B/EP, if Vf is replaced by 0.78 and 0.957 respectively, then the mean deviation & may be decreased to less than 0.8 and 1.2.In view of the present situation, it is proposed to use Eqs.4, 5 or Eq. 6 as the TWO-STEP MODEL for predicting ET and GLT of a com do- site, because those equations are simple and unified, also easily to use. The main point is that those equations are based on a clearer physical concept, therefore it is more acceptable and it can give out the most preferable predictions.
出处
《复合材料学报》
EI
CAS
CSCD
北大核心
1990年第2期81-88,共8页
Acta Materiae Compositae Sinica
