Purpose

Auxetic structures are one type of mechanical meta-materials mainly used for energy absorption applications because of their unique negative Poisson’s ratio. This study is focused on numerical and experimental investigations of fused deposition modeling (FDM) fabricated re-entrant auxetic structures of acrylonitrile butadiene styrene (ABS) and poly-lactic acid (PLA) materials under compressive loading. Influence of geometric parameters, namely, re-entrant angle, height and arm-length on strength, stiffness and specific energy absorption (SEA) of auxetic structures under compressive loading. Optimization of significant parameters is also performed to maximize these responses and minimize weight and time of fabrication. Further, efforts have also been made to develop predictive models for strength, stiffness and SEA of auxetic structures.

Design/methodology/approach

A full factorial design of experiment is used for planning experiments. Auxetic structures of ABS and PLA are fabricated by FDM technique of additive manufacturing within the constrained range of geometric parameters. Analysis of variance is performed to identify the influence of geometric parameters on responses. To optimize the geometric parameters Gray relational analysis is used. Deformation of auxetic structures is studied under compressive loading. A numerical investigation is also performed by building nonlinear finite element models of auxetic structures.

Findings

From the analysis of results, it is found that re-entrant angle, height and arm-length with their interactions are significant parameters influencing responses, namely, strength, stiffness and SEA of the auxetic structures of ABS and PLA materials. Based on the analysis, statistical nonlinear quadratic models are developed to predict these responses. Optimal configurations of auxetic structure of ABS and PLA are determined to maximize strength, stiffness, SEA and minimize weight and time of fabrication. From the study of deformation of auxetic structures, it is found that ABS structures have higher energy absorption, whereas PLA structures have better stiffness. Results of finite element analysis (FEA) are found in good agreement with experimental results.

Research limitations/implications

The present study is limited to re-entrant type of auxetic structures of ABS and PLA materials only under compressive loading. Also, results from the present study are valid within the selected range of geometric parameters. The findings of the present study are useful in maximizing strength, stiffness and SEA of auxetic structures that have wide applications in the automotive, aerospace, sports and marine sector.

Originality/value

No literature is available on studying the influence of geometric parameters, namely, re-entrant angle, height and arm-length of auxetic structure on strength, stiffness and SEA under compressive loading. Also, a comparative study of feedstock materials, namely, ABS and PLA, is also not reported. The present work attempts to fulfill the above research gaps.

中文翻译：

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FDM压缩载荷下FDM制造的ABS和PLA材料凹入流变结构的数值与实验研究。

目的

辅助结构是一种主要用于能量吸收应用的机械超常材料，因为它们具有独特的负泊松比。这项研究的重点是在压缩载荷作用下，熔融沉积建模（FDM）制造的丙烯腈-丁二烯-苯乙烯（ABS）和聚乳酸（PLA）材料的凹入流变结构的数值和实验研究。几何参数，即凹角，高度和臂长，对压缩载荷下拉力结构的强度，刚度和比能量吸收（SEA）的影响。还执行重要参数的优化以最大化这些响应并最小化制造的重量和时间。另外，还已经努力开发用于膨胀结构的强度，刚度和SEA的预测模型。

设计/方法/方法

实验的完整析因设计用于计划实验。ABS和PLA的辅助结构是通过在有限的几何参数范围内通过增材制造的FDM技术制造的。进行方差分析以识别几何参数对响应的影响。为了优化几何参数，使用了灰色关联分析。在压缩载荷下研究了拉力结构的变形。数值研究还通过建立非球面结构的非线性有限元模型来进行。

发现

通过对结果的分析，发现凹角，高度和臂长及其相互作用是影响响应的重要参数，即ABS和PLA材料的膨胀结构的强度，刚度和SEA。基于分析，开发了统计非线性二次模型来预测这些响应。确定ABS和PLA的膨胀结构的最佳配置，以使强度，刚度，SEA最大化，并使制造的重量和时间最小化。通过对膨胀结构变形的研究，发现ABS结构具有较高的能量吸收，而PLA结构具有较好的刚度。发现有限元分析（FEA）的结果与实验结果非常吻合。

研究局限/意义

本研究仅限于在压缩载荷下凹入型ABS和PLA材料的膨胀结构。同样，本研究的结果在选定的几何参数范围内有效。本研究的发现有助于最大化在汽车，航空航天，体育和海洋领域具有广泛应用的膨胀结构的强度，刚度和SEA。

创意/价值

没有文献可用来研究几何参数的影响，即凹形结构的凹角，高度和臂长对压缩载荷下的强度，刚度和SEA的影响。另外，也没有报道对原料材料即ABS和PLA进行比较研究。目前的工作试图弥补上述研究空白。