Abstract

This paper investigates the possibility of producing an equivalent structural behaviour of two components each consisting of a different material. This is achieved through the implementation of structural optimizations. It is assumed that the initial structure is produced by conventional injection moulding and the structure to be optimized is 3D printed. For comparison, two material pairings currently used in both processes are considered. As a structural optimization method, thickness optimizations are performed in order to change the resulting cross-section of the prototype. At the beginning, the mechanical problem is formulated analytically and methods for structural optimization are evaluated. With finite element analysis, two methods are presented, which introduce the generation of a variable thickness distribution in rib structures. The first method represents a state-of-the art optimization. Ribs are directly optimized by approximating cross-section forces and moments of the prototype rib and the initial rib. The second method represents a new approach to the optimization of thin-walled structures. Local stress distributions and resulting triaxiality states, which are approximated in an intermediate step, are analysed. A newly developed finite element structure is presented, with which it is possible to generate discrete triaxiality fields and determine the necessary local thickening. This method can be used in order to produce functional prototypes in early design stage. The substituted plastic parts are usually produced by injection moulding, which initially requires a high expenditure of time and money for tool construction. Additive manufacturing represents a solution here to accelerate the development process. However, these 3D-printed prototypes are, regarding the material properties and resulting mechanical behaviour, different to the injection-moulded ones.

中文翻译：

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尺寸优化方法近似于热塑性塑料的等效机械性能

摘要

本文研究了产生由相同材料组成的两个组件的等效结构行为的可能性。这是通过实施结构优化来实现的。假定初始结构是通过常规注塑成型生产的，并且要优化的结构是3D打印的。为了进行比较，考虑了两种工艺中当前使用的两种材料配对。作为结构优化方法，执行厚度优化以更改原型的最终横截面。刚开始时，通过分析来制定机械问题，并评估用于结构优化的方法。通过有限元分析，提出了两种方法，它们介绍了在肋骨结构中产生可变厚度分布的方法。第一种方法代表了最先进的优化。通过近似横截面力和原型肋骨和初始肋骨的矩来直接优化肋骨。第二种方法代表了一种优化薄壁结构的新方法。分析了在中间步骤中近似的局部应力分布和所得的三轴状态。提出了一种新开发的有限元结构，利用它可以生成离散的三轴场并确定必要的局部增厚。此方法可用于在设计的早期阶段生产功能原型。替代的塑料零件通常是通过注塑成型生产的，这首先需要花费大量时间和金钱来制造工具。增材制造是加速开发过程的解决方案。但是，这些3D打印的原型在材料特性和产生的机械性能方面与注塑成型的原型不同。