Purpose

This paper aims to focus on studying the influence of gradient parameters, namely, thickness coefficient, length coefficient and height ratio of auxetic structure on responses such as strength, stiffness and specific energy absorption (SEA) under compressive loading. Optimization of significant parameters is also performed to maximize responses. Further, efforts have also been made to develop regression models for strength, stiffness and SEA of auxetic structure.

Design/methodology/approach

Central composite design of response surface methodology is used for planning experiments. Auxetic structures of acrylonitrile butadiene styrene (ABS) and poly-lactic acid (PLA) materials are fabricated by the material extrusion (ME) technique of additive manufacturing. Fabricated structures are tested under in-plane uniaxial compressive loading. Grey relational analysis is used for the optimization of gradient parameters of the unit cell of auxetic structure to maximize responses and minimize weight and time of fabrication.

Findings

From the analysis of variance of experimental data, it is found that the compressive strength of auxetic structures increases with a decrease in length coefficient and height ratio. In the case of ABS structures, stiffness increases with a decrease in thickness coefficient and length coefficient, while in the case of PLA structures, stiffness increases with a decrease in length coefficient and height ratio. SEA is influenced by length coefficient and thickness coefficient in ABS and PLA structures, respectively. Based on the analysis, statistical non-linear quadratic models are developed to predict strength, stiffness and SEA. Optimal configuration of auxetic structure is determined to maximize strength, stiffness, SEA and minimize weight and time of fabrication.

Research limitations/implications

The present study is limited to re-entrant type of auxetic structures made of ABS and PLA materials only under compressive loading. Also, results from the current study are valid within a selected range of gradient parameters. The findings of the present study are useful in the optimal selection of gradient parameters for the fabrication of auxetic structures of maximum strength, stiffness and SEA with minimum weight and time of fabrication. These outcomes have wide applications in domains such as automotive, aerospace, sports and marine sectors.

Originality/value

Limited literature is available on studying the influence of gradient parameters of ME manufactured auxetic structure of ABS and PLA materials on responses, namely, strength, stiffness and SEA under compressive loading. Also, no work has been reported on studying the influence of gradient parameters on mechanical properties, weight and time of fabrication of auxetic structures. The present study is an attempt to fulfil the above research gaps.

中文翻译：

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材料挤压制造的拉胀结构：梯度参数的实验研究

目的

本文旨在重点研究梯度参数，即拉胀结构的厚度系数、长度系数和高度比对压缩载荷下强度、刚度和比能量吸收（SEA）等响应的影响。还执行重要参数的优化以最大化响应。此外，还努力开发拉胀结构的强度、刚度和 SEA 的回归模型。

设计/方法/方法

响应面方法的中心复合设计用于规划实验。丙烯腈丁二烯苯乙烯 (ABS) 和聚乳酸 (PLA) 材料的拉胀结构是通过增材制造的材料挤出 (ME) 技术制造的。制造的结构在平面内单轴压缩载荷下进行测试。灰色关联分析用于优化拉胀结构晶胞的梯度参数，以最大化响应并最小化重量和制造时间。

发现

从实验数据的方差分析发现，拉胀结构的抗压强度随着长度系数和高度比的减小而增加。对于ABS结构，刚度随着厚度系数和长度系数的减小而增加，而对于PLA结构，刚度随着长度系数和高度比的减小而增加。SEA 分别受 ABS 和 PLA 结构中的长度系数和厚度系数的影响。基于分析，开发了统计非线性二次模型来预测强度、刚度和 SEA。确定拉胀结构的最佳配置以最大化强度、刚度、SEA 并最小化重量和制造时间。

研究限制/影响

目前的研究仅限于仅在压缩载荷下由 ABS 和 PLA 材料制成的再入型拉胀结构。此外，当前研究的结果在选定的梯度参数范围内有效。本研究的结果可用于优化选择梯度参数，以制造具有最大强度、刚度和 SEA 的拉胀结构，同时具有最小的重量和制造时间。这些成果在汽车、航空航天、体育和海洋等领域有着广泛的应用。

原创性/价值

关于研究 ME 制造的 ABS 和 PLA 材料的拉胀结构的梯度参数对压缩载荷下的响应（即强度、刚度和 SEA）的影响的文献有限。此外，还没有研究梯度参数对拉胀结构的机械性能、重量和制造时间的影响。本研究试图弥补上述研究空白。