This study aimed to investigate the mechanical properties and thermal properties of epoxy composites reinforced jute and coconut fibers with varied rice husk ash (RHA) percentages for thermal insulation in building wall insulation. In this study, according to ASTM standards, the seven types of composite samples with varying filler ratios were prepared using the hand lay-up process. The four jute fiber (JF) samples were prepared with RHA at 0 % (control), 1 %, 2 %, and 3 % of total weight respectively, while the other three coconut fiber (CF) samples were prepared with CF at 0 % (control), 1 %, and 3 % RHA, respectively. The mechanical and thermal properties were measured for repeated three samples by using the UTM and TRSYS101 units, respectively. Regarding the mechanical characteristics, tensile strength increased with the increment of filler percentage for jute fiber composites, however, tensile strength reduced in the coconut coir composites as the filler percentage increased. The jute fiber composite sample consisting of 3 % RHA was found to be the highest among the seven composite samples, with a maximum ultimate tensile strength of 50.07 MPa and the highest tensile modulus of elasticity (2.85 GPa) with better energy absorption property. In terms of flexural strength tests, with the increase of filler percentage in coconut coir composites, the flexural properties decreased as well. On the contrary for jute fiber composites, 3 % RHA-JF composite had the highest flexural strength and moderate flexural modulus of elasticity. This study also found that with the increase of RHA percentage in JF composites, the thermal conductivity decreases, with a minimum value of 0.03697 W/m.K was found in 3 % RHA-JF composite, while in CF composites, it increased with the filler percentage. However, the combined uncertainties of mechanical properties (tensile and flexural) are estimated at 4.57 % and 4.93 %, respectively, while estimated at 5.67 % for thermal conductivity measurement. As, 3 % RHA-JF composite offers low thermal conductivity, good strength, and energy absorption, it is suitable for thermal insulation applications. Furthermore, the heat transfer analysis has been studied analytically by considering two types of wall insulation configurations (type 1 and type 2). Due to its easy capability to insert or attach inside the wall insulation and get almost similar heat transfer rate, type 2 is considered in actual practice of wall insulation. Moreover, the scope of this study is to explore agricultural waste to reduce environmental impact and enhance energy efficiency through thermal insulation inserted inside the domestic building's wall.

This study aims to develop an exact analytical solution for steady-state thermo-mechanical stress in a functionally graded (FG) thick-walled cylindrical vessel. The cylinder is subjected to combined rotational speed and internal pressures while the thermal load is with convective and radiative boundary conditions. The dimensionless governing equations and boundary conditions, represented as a quartic equation, are derived and solved using Ferrari's method. The temperature, displacement, and stress fields across the thick-walled cylindrical vessel are calculated by finding the roots of the quartic equation. In order to investigate the accuracy of the exact analytical solution, a numerical model is constructed based on a standard Galerkin discretization approach of the finite element method (FEM). The analytical solutions and the results obtained through FEM show a high level of agreement. Furthermore, the study analyzes the effects of material parameters on temperature, displacement, and stress fields. Displacement, temperature, and stress fields are presented in the form of dimensionless graphs along the radial direction. For the considered parametric studies, results revealed that parabolic grading is beneficial than conventional grading. This study reveals that for the thermal loading, the maximum temperature, displacement, and tangential stress decrease for the parabolic grading. A similar but lower value of temperature, displacement, and tangential stress is also observed in the case of thermomechanical loading. This study is expected to assist in the assessment of the reliability of load calculations and contribute to the overall durability of pressure vessels. The results obtained from this study can provide valuable insights into thermo-elasticity and the thermo-mechanical behavior of thick-walled cylindrical vessels and can aid in the design and optimization of such systems.