Experimental Study on Dynamic Compression Mechanical Properties of Aluminum Honeycomb Structures

Sheng Zhang,Longbao Han,Wei Chen,Liping Xiao,Deping Gao

doi:10.3390/app10031188

Sheng Zhang, Longbao Han + Show 3 more

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https://doi.org/10.3390/app10031188

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Abstract

In this paper, dynamic compression tests are developed to investigate the dynamic compression mechanical properties of the aluminum honeycomb structures at different strain rates, especially at the high strain rates. The difficulties at the high strain rates exist due to the large deformation, the low wave resistance and the size effect of the honeycomb structures. The Split Hopkinson Pressure Bar (SPHB) test method is carried out and special measures such as the adoption of waveform shaper, the size optimization of the impact bar and the specimen, and employment of the semiconductor strain gauge, etc. are taken to overcome the difficulties. It is discovered that the dynamic compression mechanical properties possess a stress hardening effect at a high strain rate from 1.3 × 103 s−1 to 2.0 × 103 s−1, but then a stress softening effect at a high strain rate of 4.6 × 103 s−1. It is also discovered that the yield strength and the average plateau stress at the strain rate of 2.0 × 103 s−1 is higher than that at the strain rate of 1.3 × 103 s−1. However, the yield strength and the average plateau stress at the strain rate of 4.6 × 103 s−1 is lower than that at the strain rate of 2.0 × 103 s−1 and 1.3 × 103 s−1, but higher than that at a quasi-static state. This indicates that the aluminum honeycomb structure is sensitive to the strain rate. Additionally, the damage mode of the aluminum honeycomb structure is plastic buckling, collapse and folding of the cell wall, which is carried out using dynamic compression tests. The folding length of the cell wall at a higher strain rate is found to be longer than that at a lower strain rate. The test results can also be used as the stress–strain curves of the honeycomb constitutive model at the high strain rates to carry out the numerical simulation of high-speed impact.

Highlights

With advantages of low weight, large specific stiffness, and high specific strength, the metal honeycomb sandwich structure is extensively applied in the field of aerospace engineering
The results of the dynamic compression tests under the strain rate at 1 × 103 s−1 are shown in 8 ofthe and the stress–strain curves are shown in Figures 9 and 10 respectively
Is a slight oscillation in the stress obtained from the test, which is attributed to the weak divergence of the stress wave the high strain rate

Summary

Introduction

With advantages of low weight, large specific stiffness, and high specific strength, the metal honeycomb sandwich structure is extensively applied in the field of aerospace engineering. The high-bypass turbofan engine casing is made from the honeycomb sandwich structure in order to. Sci. 2020, 10, 1188 improve the impact resistance since the impact on the casing is a typical nonlinear physical process with the high strain rate up to 104 s−1 during the fan blade out events. The high strain rate has a great influence on the mechanical properties of the structure. The different honeycomb structures possess different cell structure characteristics and mechanical properties, it is crucial to understand the dynamic compression mechanical properties of the aluminum honeycomb structures at a high strain rate

Methods

Results

Conclusion