Mechanics and Failure Analysis of Stitched Sandwich Structures Damaged by a Second Impact of Various Energies.

Abstract

In the fields of structural mechanics and failure analysis, the presence of damage to structural materials requires several studies. Expertise in damage is crucial to understand the behavior of structures under various loading conditions. Generally, this damage affects the most stressed area of the structure and can lead to the accumulation and propagation of damage, resulting in the partial or total collapse of the structure.On the other hand, stitched sandwich plates are an innovative structural material with extremely high performance in the fields of building mechanics and others. However, when these plates are damaged, it is essential to study their behavior under subsequent loading conditions to assess their ability to withstand a second impact. After having been damaged by a first impact at low speed, a diagnosis was carried out, which showed the capacity of these plates to undergo a new shock.The present work focuses on the study of the behavior of these said plates under the effect of a second impact. First, the plates subject to damage in previous works were subjected to a new constant energy impact to observe the cumulative effect. In the second part, repeated impact tests were applied to healthy plates according to two different modes. The diversity of impact modes is based on the cycle (time) factor: an immediate repeated shock, whereas for the other mode, the specimen only suffers a second shock after a rest of 24 hours.An analysis of the behavior of the sandwich plates under the effect of different shocks (without rebound) was carried out. The results obtained showed once again the effectiveness of these structural materials in the face of the impact compared to traditional sandwiches. The damage seen is characterized by positioning and pivoting around the point of impact and is limited to the edges of the collider's diameter and depth. Fracture analysis of these plates indicated that the damage resulted in a decrease in their bearing capacity