Stress Concentration factors in cylindrical bars under axial load and constant bending moment using FEA method

Introduction

Designing a product with good quality costs the industry very high, and increases the product’s price. Because a good quality product needs careful design, proper material, and long running lifetime, we need to invest much money for this purpose. There are many aspects to be considered to design an overwhelming product. Otherwise, the designed part will fail.

One of the causes is not consciously considering and analyzing the stresses due to the load on the part. We can easily calculate the stress on a uniform part. Finding the stress on a groove or a shape changing portion is not really easy and needs to be found very carefully because the stress on this portion is very high comparing to other places of the part, and often the failure occurs on this portion. Since finding the stress on the shape changing portion is much complicated, we need to define a factor to simplify the calculation and avoid time consumption. The factor is defined as the “stress concentration factor (kt).” This factor is found theoretically and plotted in different graphs, and is also possible to be found by using any “Finite Element Method Software”, or any other experimental measuring devices such as strain gage. In this project, we are assigned to find stress concentration factors using commercial FEA software (preferably COSMOSWORKS). Since there are many graphs of stress concentration factors for different shapes, I am assigned to find the stress concentration factor kt for a U-shape grooved cylindrical shaft in tension and bending which are the figures A-15-13 and A-15-14 in the machine design text book’s appendices. The full report can be found from here