短纤维增强EPDM包覆薄膜超弹性本构模型

短纤维增强三元乙丙橡胶(EPDM)包覆薄膜用于一种新型缠绕包覆工艺,主要解决复杂构型自由装填药柱外表面可靠性包覆问题.为了描述其在固体火箭发动机工作过程中产生的大变形、非线性和各向异性等力学行为,根据纤维增强复合材料连续介质力学理论,提出了各向异性超弹性本构模型.该模型中单位体积的应变能函数被解耦成两部分:表征各向同性的橡胶基体应变能和表征各向异性的纤维拉伸应变能,通过引入纤维方向对纤维应变能进行修正,给出了通过单轴拉伸、偏轴拉伸实验数据获取模型参数的具体方法.研究结果表明,该模型能够很好地预测材料在纤维方向0°~45°时的各向异性力学特性,并将预测结果与实验数据对比,误差在5%以下.所建立的各向异性超弹性本构模型准确性高、易于实现数值开发,在一定程度上能够为固体火箭发动机的装药结构完整性分析提供理论依据.

HYPERELASTIC CONSTITUTIVE MODEL FOR SHORT FIBER REINFORCED EPDM INHIBITOR FILM

Short fiber reinforced EPDM inhibitor film is used for a new winding coating process, which is mainly to solve the reliable problem in free loading solid rocket grains with complicated structure. Based on fiber reinforced continuum mechanics theory, a simple anisotropic hyperelastic constitutive model is proposed to describe their large deformation, highly non-linear and strongly anisotorpic mechanical behaviors in the work process of solid rocket motor. The unitvolume strain energy function is decomposed into two parts:representing the strain energy from isotropic rubber matrix and anisotropic fiber tensile deformation. By introducing fiber direction to modify fiber strain energy, the specific method of obtaining model parameters by uniaxial and off-axis tension data is presented.Results show that it is highly suitable to characterize their anisotropic mechanical behaviors in the fiber direction from 0° to 45° and the error is less than 5% compared with experimental data. It is concluded that the proposed model is highly accurate and easy to achieve numerical development, which can provide theoretical basis for the structural integrity analysis of solid rocket motor.