Design Optimization of Leaf Spring Using FEM and RSM

Abstract

Abstract: The prime objective of this design and analysis work is to design a Pressure vessel by following the standards of American Society of Mechanical Engineers (ASME). Pressure vessel as a subject matter was opted for the design and analysis with a principal aim to minimize the stress being produced within the structure by structural modification in the Pressure vessel by using analytical approach. ASME (BPVC) Sec-VIII Div- I and Div-II was used to follow the Design by Rule (DBR) and Design by Analysis (DBA) approach. Along with that ASME (BPVC) Sec-II Part- A and Part- D was followed. Cylindrical, Horizontal bullet type Pressure vessel with Hemispherical head was used for this analysis .This work was intended for Stress Minimization within the structure as a principal aim, which is being caused by the exertion of pressure of the fluid on the internal wall and for this SA516Gr65 and SA537 CL 1 material was selected form ASTM Library. This designed Pressure vessel to be used for the LPG gas storage under the internal design pressure of 1.55MPa at 55°C. The design and analysis work was carried out in two sections Design by Rule (DBR) which is a conventional design, for that empirical formula was used to calculate the value of stress being produced under the given conditions and for the required thickness of the shell, head and nozzle to sustain the applied pressure of fluid by following the standards of ASME (BPVC) SecVIII Div- I and Deign by Analysis (DBA), which is a analytical design approach, here Finite Element Method (FEM) was opted for the analysis of the designed model, which was done in the CATIA V5, here in the CATIA two models, Model 1 and Model 2 were created and a structural modification was done in the model 2 and then analysis was performed in the Ansys Workbench 16.0. The comparison was made for both the design approach for the minimized stress values of Hoop Stress and Longitudinal Stress by structural modification and the required thickness under the alternative materials selections criteria was discussed. Up to 25% less stress value was seen in comparative structural analysis of Model 1 and Model 2. This report also discusses the use of SA537 CL 1 material as an alternative options which helps to reduce the thickness of the vessel when compared to the existing materials because this material can sustain the same amount of pressure under given condition at a thinner shell also, this is numerically proved here in this work. Keywords: Pressure Vessel, ASME, Stress Minimization, LPG, FEM, DBR, DBA, Optimum Design.