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Dynamic Analysis of Modified Hybrid Symmetric Bistable Lamin

Diab, Ibrahim Khalil
A Master of Science thesis in Mechanical Engineering by Ibrahim Khalil Diab entitled, “Dynamic Analysis of Modified Hybrid Symmetric Bistable Lamin”, submitted in November 2023. Thesis advisor is Dr. Samir Emam. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).
Bistable laminates have been studied for decades. Their ability to take a stable shape with minimal actuation force has given them much attention and research for morphing applications. Multiple studies have been done to determine how laminates behave under different configurations. Studies include modified hybrid bistable laminates (m-HBSL). Most studies examine the laminate’s behavior under specific loading conditions. To better simulate the use of bistable laminates into real life applications, the response under dynamic loadings must be investigated. Yet, the m-HBSL behavior hasn’t been studied under dynamic loading conditions. This report presents a detailed literature review on the history of bistable laminates to date. Furthermore, an m-HBSL model is studied using ABAQUS. The model investigates three different case studies on the same structure. In all cases, the laminate settles at one of the static equilibrium positions. In the first case, a concentrated dynamic load at the tip of the free edge of the laminate is applied. The second case involves a uniform pressure on the laminate. The third case involves an out of plane displacement applied to the cantilevered end of the laminate. The main objective is to identify the dynamic snap through load and compare it with the static counterpart. Meanwhile, the application of dynamic loads investigates the single-well and double-well response. It is found out that under the dynamic loading, the laminate snaps at lower loads compared with the static snap through. It was found that the laminate will snap at 85% less load under harmonic loads than the static counterparts. However, the laminate will require 35% less load to snap dynamically under pressure loading. Meanwhile, the resonant response shows a periodic single well, chaotic double well, and periodic double well as the load is varied. This emphasizes the crucial role that dynamic response has for the analysis and design of bistable symmetric laminates. Furthermore, the laminate shows a change in shape when higher tip loads are applied. Finally, the laminate shows no steady state response when actuated using the other two loading techniques.
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