Analysis of Hydraulic Excavator

Abstract

The surge in construction industry has put the designer of excavation equipments in a crucial role. With the increase in productivity of these machines the safe working of these machines is also very important. The objective of this project was to analyze the design of attachment of excavator and redesign them if they are failing or there is a chance of improvement in terms of stresses and weight reduction. This report focuses on analyzing the design of excavator attachments i.e. Bucket, Arm and Boom. Forward kinematic model was used for the backhoe mechanism for generalized force calculation for 3 degrees of freedom. This model can be used to simulate the digging process and forces can be calculated. A MATLAB code was also developed for the same. Using this model orientation of the backhoe attachment was found out for maximum breakout force. Static force analysis of bucket, arm and boom was done for backhoe mechanism considering maximum breakout force using SAE J1179. The forces calculated using this model were used as a boundary conditions for Finite Element Analysis. Solid model of each part was created using CATIA V5. These models were imported to Hypermesh for meshing using STEP model. For each part different components were created and different material properties were given to each component as per its application. The Linear Static Finite Element Analysis was carried out and used to find the deformation in the and the stresses generated in the parts. These stresses were used to identify the areas of modification and weight reduction was done for bucket, arm and boom. The arm and boom were having some higher stress regions at maximum breakout force condition. These regions were modified for better performance. Thickness of plates for attachments was reduced using FEA results where the stresses were less, in some areas shape was modified to reduce the stresses. There were some areas where extra material was added to reduce the stresses as well. The stresses developed in the model after modification was reduced to allowable stresses for each component. The weight reduction of Bucket, Arm and Boom was 8.92%, 8.69% and 5.86% respectively. FEA was done using Hyperworks Optistruct solver and Hypermesh softwares.