Due to low thermal conductivity and high heat of ablation, thermoset composites are extensively used in thermal protection systems under high temperature environments. Ablation is a process of spending heat energy at the loss of structural material. There are two types of ablative materials: 1) Melting type and 2) Non-melting type. Melting type ablators (Thermoplastics) change from solid to liquid when subjected to heat, hence not suitable for temperature applications. Non-melting type ablators are classified in to low temperature ablators (LTAs) and high temperature ablators (HTs). HTAs are capable of withstanding high temperatures and subsequently get removed by oxidation (>1100 K). LTAs when subjected to low temperatures (>600 K), decompose and form gasses and charring material on the surface of the structure. This charring material acts as a thermal protector and subsequently gets removed by influence of external force due to lack of strength. Thermoset composites are examples of LTAs. Ablation behaviour of composite cylinders made of LTAs under axisymmetric thermal loading and internal pressure is presented in the current work.
As the material properties of composites are dependent on temperature, finite element model for transient axisymmetric heat transfer analysis of cylinders with nonhomogeneous, temperature-dependent material properties is considered and the transient temperature distribution in the cylinder is obtained. Temperatures obtained are used for static stress analysis of cylinder. A high precision axisymmetric ring element having twelve degrees of freedom with fourth order numerical integration is employed for static stress analysis. The finite element model presented can be used to analyze the layered composite cylinders under combined internal pressure and axisymmetric thermal loading.