Background

Conventional composites used in damping applications exhibit an undesirable tradeoff between stiffness and energy dissipation. Recent research demonstrates that it is possible to simultaneously achieve increased stiffness and energy dissipation for a configuration of a viscoelastic polymer matrix placed in parallel with a negative stiffness structure (NSS). This configuration resulted in energy dissipation equal to the sum of its components but is difficult to implement in practice.

Objective

In this paper, an alternative configuration is investigated in which the NSS is embedded simultaneously in series and parallel with the matrix. The main objectives are to examine the tradeoff between the stiffness and energy dissipation of the composite and to identify the mechanisms for enhanced energy dissipation.

Methods

To achieve this, FEA models were used to match the stiffness of a polymer matrix with that of a metallic NSS. Multiple specimens were manufactured and tested under quasi-static compressive loads to determine the force versus displacement curves and calculate the energy dissipation and stiffness.

Results

These tests demonstrate that the total energy dissipation of the composite can be greater than the sum of its components, while maintaining the benefit of increasing the stiffness and damping capacity simultaneously. The results also demonstrate that the applied strain rate plays a critical role in activating the NSS, which is essential to achieve the desired increase in energy dissipation.

Conclusions

The results indicate that localized strain and strain rate at the interface between the NSS and polymer matrix are the main contributors to achieving energy dissipation beyond the sum of its components. Furthermore, it was demonstrated that the strain rate affects the activation of the NSS and therefore composites containing mechanically activated NSS must be designed for the strain rate of interest.

中文翻译：

---

含嵌入金属负刚度结构的聚合物基复合材料的刚度和耗能

背景

用于阻尼应用的常规复合材料在刚度和能量耗散之间表现出不希望的折衷。最近的研究表明，对于与负刚度结构（NSS）平行放置的粘弹性聚合物基体，可以同时实现更高的刚度和能量耗散。这种配置导致的能量耗散等于其组成部分的总和，但是在实践中很难实现。

客观的

在本文中，研究了另一种配置，其中NSS同时与矩阵串联和并联嵌入。主要目标是检查复合材料的刚度和能量耗散之间的权衡，并确定增强能量耗散的机制。

方法

为了达到这个目的，使用FEA模型将聚合物基体的刚度与金属NSS的刚度进行匹配。制造了多个试样，并在准静态压缩载荷下进行了测试，以确定力与位移的关系曲线，并计算出能量耗散和刚度。

结果

这些测试表明，复合材料的总能量耗散可能大于其成分的总和，同时保持了同时增加刚度和阻尼能力的好处。结果还表明，所施加的应变率在激活NSS中起着关键作用，这对于实现所需的能量耗散增加至关重要。

结论

结果表明，NSS和聚合物基体之间的界面处的局部应变和应变率是实现能量耗散的主要因素，其组成总和之外。此外，已证明应变速率影响NSS的活化，因此必须针对感兴趣的应变速率设计包含机械活化的NSS的复合材料。