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Experimental ٍٍExtraction of Thermomechanical Behavior of Carbon/Phenolic Nanocomposite Ablative Coatings to Develop Failure Model

Jafari, Hamid Reza | 2025

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 58907 (45)
  4. University: Sharif University of Technology
  5. Department: Department of Aerospace Engineering
  6. Advisor(s): Hosseini Kordkheili, Ali
  7. Abstract:
  8. Thermal protection systems are ablative composite coatings that, through endothermic reactions, protect the main structure or underlying layers under high thermal loads. Under these conditions, various phenomena occur, such as pyrolysis, char formation and char cracking, surface recession, as well as different modes of heat transfer including conduction, convection, and radiation. Successful simulation of the ablation phenomenon will lead to the development of a tool that greatly assists in the design of thermal protection systems for atmospheric re-entry vehicles.The primary focus of this dissertation is the experimental investigation of the ablation process, or surface recession, of carbon/phenolic composites under high heat fluxes. Another objective of this research is the numerical simulation of the ablation phenomenon using the commercial software Abaqus and its capability to define material properties via UMAT (User MATerial subroutine). To carry out this simulation, various data are required, including thermophysical properties of the materials, an appropriate failure model, and a suitable numerical solution algorithm. The thermophysical data are extracted through standard tests. A plasma arc test is conducted on standard specimens to experimentally determine the surface recession rate of the carbon/phenolic composite. This value serves as a reference indicator during numerical simulation.An appropriate failure model is proposed and experimentally evaluated. The effect of nanoparticles on thermal stability and the char yield of the carbon/phenolic composite is also studied. Simulation results from Abaqus indicate that modeling the char layer and considering char properties in the ablation simulation lead to more accurate results. When char properties are included in the simulation of surface recession, the discrepancy between numerical and experimental results is approximately 12.57%. However, if char properties are neglected, this discrepancy triples to about 38%
  9. Keywords:
  10. Thermal Protection System (TPS) ; Numerical Simulation ; Carbon/Phenolic ; Ablation Phenomenon ; Plasma Arc Test ; Functionalized Nanoparticles

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