Session: 01-09-01: Peridynamics and Its Applications

Paper Number: 107476

107476 - Peridynamic Modeling of Sand Particle Impact Damage in Charring Materials Due to Ablation 

Space vehicles can attain a speed up to Mach 25 during their re-entry phase into the earth’s atmosphere. At the stagnation point, the vehicle is exposed to severe aerodynamic heating of the order cube of the velocity and the surface temperature can reach 3000K. The immense aerodynamic heating can have detrimental effects on the payload and experimental probes in the vehicle. To prevent the vehicle from reaching a certain critical temperature, thermal protection systems (TPS) are used at the outer surface that acts as a thermal barrier to the actual structure.  Polymer ablatives can be classified as non-charring and charring. In non-charring materials, the material degradation is limited to the surface whereas a charring ablative undergoes internal decomposition causing the change in material properties. A charring TPS starts as virgin material and as the heat penetrates during the re-entry, thermal decomposition of material occurs when the temperature rises above the glass transition temperature.  A charring TPS is an important structure in hypersonic vehicles as it prevents hot air from entering vehicles and potential impacts from space debris.  When traveling at speeds up to Mach 25 mph, the impact of sand and dust particles can be significantly disturb the surface of the vehicle, and potentially alter its aerodynamic response due to the change in fluid flow.  Modeling material, thermal and impact response of an ablative TPS require numerical solution to thermal energy balance and mechanical energy balance coupled with the internal decomposition.  As more interplanetary missions are being explored use of new materials for TPS designs are in consideration and it is imperative to understand the thermo-mechanical behavior and failure mechanisms in TPS materials.

This study presents a bond-based peridynamic model of thermo-mechanical coupling for charring material to demonstrate the crack propagation during the process of thermal decomposition as well as the evolution of cracks emanating from the impact regions. The overall chemical reaction of charring material is represented by the density change, which can be determined using the Arrhenius equation. The PD form of the equilibrium equation is recast by considering both the effect of temperature and shrinkage strain due to mass loss.  A transient analysis is performed for simulating the motion of rigid sand particles based on the concepts from multi-body dynamics.  The shape and impact angle of the sand particles are arbitrary and representative of the actual sand particle. The friction between the sand particles and ZnS plate is included in the contact law.

Presenting Author: Erdogan Madenci University of Arizona

Presenting Author Biography: ..................

Authors:

Erdogan Madenci University of Arizona
Yanan Zhang University of Arizona
Sundaram Vinod Anicode University of Arizona