The demand for environmentally friendly materials is at its peak, and government legislations have become stricter and no longer tolerate violations. With biocomposites emerging as structural components instead of being hidden as non-structural applications and interiors, the automotive and motorsport sector started considering them for structural body parts. Natural fibres abundance, commercial availability, renewability, low density, low cost, and high tensile strength make biocomposite materials excellent candidates for eco-friendly vehicles. Several studies reported the utilisation of biocomposites as high-performance components and structural applications. However, current computer-aided engineering and modelling tools are insufficient to explore the vast field of possibilities during biocomposite materials selection to accurately predict the components' behaviour and analyses. Therefore, this study focuses on creating a material model to predict the behaviour of biocomposite materials. Additionally, the model is numerically implemented to illustrate the deformation and bending stiffness capabilities of a motorsport monocoque chassis structure application. A micromechanics modelling combining rate-dependant constitutive laws and multi-site interactions of inclusions is developed for studying the nonlinear response of composite materials. To avoid numerical instabilities when increments of time become very small, a regulation procedure concerning the visco-plastic function is adopted in the computation of the consistent tangent modulus. Based on the Generalised Mori–Tanaka (GMT) scheme, the effective properties are obtained for the nonlinear composite. The accuracy of the model is evaluated and validated by comparison results from the open literature. Finally, the developed constitutive equations are implemented as a user-defined material UMAT in a Finite Element code, leading to an application on a bio-based composite for the bamboo/flax fibre-reinforced epoxy hybrid composite materials.

中文翻译：

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用于汽车结构应用的混合生物复合材料建模

对环保材料的需求正达到顶峰，政府立法也变得更加严格，不再容忍违规行为。随着生物复合材料作为结构部件出现，而不是隐藏在非结构应用和内饰中，汽车和赛车运动领域开始考虑将其用于车身结构部件。天然纤维丰富、商业可用性、可再生性、低密度、低成本和高拉伸强度使生物复合材料成为环保车辆的绝佳候选材料。几项研究报告了生物复合材料作为高性能组件和结构应用的利用。然而，当前的计算机辅助工程和建模工具不足以探索生物复合材料选择过程中的广阔可能性，以准确预测组件的行为和分析。因此，本研究的重点是创建材料模型来预测生物复合材料的行为。此外，该模型还以数值方式实现，以说明赛车硬壳式底盘结构应用的变形和弯曲刚度能力。开发了一种结合速率相关本构定律和夹杂物多位点相互作用的微观力学模型，用于研究复合材料的非线性响应。为了避免时间增量变得很小时数值不稳定，在一致切线模量的计算中采用了有关粘塑性函数的调节程序。基于广义Mori-Tanaka (GMT)格式，获得了非线性复合材料的有效特性。通过与公开文献的比较结果来评估和验证模型的准确性。最后，所开发的本构方程在有限元代码中作为用户定义的材料 UMAT 实现，从而应用于竹/亚麻纤维增强环氧混合复合材料的生物基复合材料。