Session: 16-01-01: Poster Session: NSF-Funded Research (Grad & Undergrad)

Paper Number: 100132

100132 - Low-Velocity Impact Characterization of a Sandwich Panel With an Orthogrid-Stiffened Shape Memory Vitrimer Core 

 

In recent years, there has been a growing demand for multifunctional composites in the aerospace and automotive industries, which is due to the increasing advancement in technology. Sandwich structures, which are a form of structural composites have piqued the interest of the automotive and aerospace industries due to their relatively high specific strength, ease of fabrication, and high specific stiffness. Despite these attractive properties, they are prone to damages such as core cracking and debonding of the skin/core interface resulting from low-velocity impact events. The damages from low-velocity impacts are usually difficult to detect with the naked eye and these damages affect the structural integrity and performance of sandwich structures. Hence, it is particularly important to investigate the susceptibility of sandwich structures to failure under low-velocity impacts before their usage in real-life applications. In this work, we present a sandwich panel with an integrated orthogrid-stiffened shape memory vitrimer (SMV) core. The  SMV core will be synthesized by mixing branched polyethylenimine (PEI) and diglycidyl 1,2-cyclohexanedicarboxylate (DCN) in a ratio of 1:2. Other PEI/DCN mix ratios will also be synthesized to investigate their influence on the glass transition temperature of the vitrimer. The sandwich panels will be fabricated via manual pin-guided technology where filaments of carbon fibre will be dry-woven around hammered nails in an orthogonal way. The distance between nails will define the bay area of the sandwich panels. In addition, woven carbon fibre mats will be used as the top and bottom skins of the panel. The thermal properties of the vitrimer will be studied using Differential Scanning Calorimetry (DSC) and the mechanical behavior of the SMV cored sandwich will be examined via a uniaxial compression test at both room temperature (25°C) and above its glass transition temperature (T_g). Additionally, the shape memory behavior of the SMV will be evaluated via a thermomechanical programming cycle using its shape fixity and shape recovery ratio. The mechanical behavior of the as-fabricated sandwich panels will be investigated via a low-velocity impact (LVI) test at three locations, that is, at the node, rib, and bay areas. Damage self-healing of the impact damaged sandwich structures will be investigated. Three energies, i.e., impact energy, propagation energy, and initiation energy from the LVI will be used to assess the impact tolerance of the sandwich panels. The results from these aforementioned tests will play a crucial role in evaluating the prospect of using these structural composites for aerospace and automotive applications.

 

Presenting Author: Obed Tetteh Southern University and A&M College

Presenting Author Biography: I am currently a graduate research assistant in the department of mechanical engineering at Southern University and A&M College. My research is focused on the use of shape memory polymers for self-healing applications.

Authors:

Obed Tetteh Southern University and A&M College
Patrick Mensah Southern University and A&M College
Guoqiang Li LOUSIANA STATE UNIVERSITY