Strain Behavior of Metallic Pre-buckled Beams under Quasi-static Transverse Loading

Abstract

The behavior of pre-buckled metallic beams was investigated to determine the force thresholds as well as the maximum strains that occur in the beams when exhibiting negative stiffness behavior under quasi-static transverse loading. Maximum strains and force threshold are the two main parameters for designing pre-buckled beams for different applications such as damping, energy dissipation, vibration isolation, and impact protection. The investigated pre-buckled beams were manufactured using two materials, Aluminum 7050 and Steel 4140 alloy. The pre-buckled beams were designed using an analytical model and were expected to display monostable negative stiffness behavior during testing. A total of 14 pre-buckled beams were designed and manufactured using water jetting to be able to accurately achieve the desired profile of the beams, which is essential in exhibiting negative stiffness behavior. Aluminum 7050 and Steel 4140 alloys were specifically chosen to allow the pre-buckled beams to deform from one stable mode of buckling to another without any plastic deformation, and hence, ensure that the pre-buckled beams will recover their initial shape and the measured strains will be in the elastic zone of both materials. The actual strains and force thresholds from experimental testing were compared to the prediction of analytical models. No energy dissipation was observed in most of the tested pre-buckled metallic beams despite exhibiting negative stiffness behavior. Only beams with a Q ratio higher than 2 exhibited negative stiffness behavior. The maximum force threshold occurred at a displacement ranging from 30 % to 40 % of the total displacement for the majority of the tested beams. Beams with a Q ratio of 4 didn't exhibit the second mode of buckling, while beams with a Q ratio close to 8 exhibited clear second mode of buckling.

Department(s)

Civil, Architectural and Environmental Engineering

Keywords and Phrases

Aluminum; Buckling; Metamaterial; Negative Stiffness; Pre-buckled; Steel; Strains

International Standard Serial Number (ISSN)

2352-0124

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2025 Elsevier, All rights reserved.

Publication Date

01 Oct 2025

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