FEM Analysis And Structure Optimization Design For Shifting Spring

The shift sheet is a spring part in the torque cover of the power tools such as drills, it look like a bow and the top point of the bow is engages with the tooth in the inside track of the cover , the function is adjust the torque and location.The structure of the shift sheet define its elasticity, the elasticity influence the service life and the function. The shift will easy break if it is over tough and can't use as a localizer if it is more soft. How to find out an optimized structure to ensure a necessary function at the time of new product development is very important, normally we will make a series of samples with different structures and make a physical test to solve the problem, but the defect is the test will last a long time and we can't get a same test environment to make sure the test data is available. Engineering analysis is another way to solve these problems in the recent years, we can simulate the design part in the computer by the FEM method and change some parameters of the structure to get different result, and then we reach an optimized design after comparing them.This article base on ABAQUS which is famous nonlinear FEA software in this field to expatiate the application of structure optimize with ABAQUS in the new product development.We suppose that the root cause for the breaking of the spring sheet is just because the spring sheet has a rigid structure and when it bending, all the force are apply on the top point, after several times cycles, the sheet can't stand the high stress and break for fatigue reason. After analysis the sheet by FEM and we got the result shows the stress on the top point is pretty higher than two wings, that indicated our assumption is right.Since we found the root cause of breaking through the FEM analysis, we can also change the model of spring sheet, and then simulate it by computer till we got the best solution of the design.We made some samples under the optimized result and install it in the product to do the life testing; we found that the new design sheet has met the requirement of durability and over the design use numbers.Compare the FEM to the traditional design method; it's not hard for us to draw a conclusion that the FEM is helpful to find the solution way and short the product design cycle.