Simulation of Stress Concentrations in Notches

The fatigue life curves of materials are very sensitive to the magnitude of the stress amplitude. A small change or inaccuracy in the determination of the stress value causes large changes or inaccuracies in the calculated fatigue life estimate. Therefore, the use of computer simulations for fatigue life estimation requires a proper model development methodology. The paper is devoted to the problem of the modeling of components in notches using FEM. The modeling parameters significantly influencing the obtained stress results have been defined. Exact analytical solutions served as a benchmark for comparing the accuracy of the stress values obtained using FEM models. For the selected 2D and 3D notched components, diagrams were created for sensitivity analysis of the influence of the mesh element density at the root of the notch in correlation with the exact analytical solution. The findings from model building were applied to model the stress concentration at the root of a V-weld joint in a gas pipeline.

Lightweight Material Optimization of Aquatic Vehicles’ Propeller Based on Fatigue Life Using Hydro Structural Interaction Simulation

Generally, inward and outward effects are huge and prime in the rotating components. Based on the working environments of a rotor, the complexity is increased furthermore. Similarly, this work also deals the complicated problem, which is fatigue life estimation of Marine Vehicles’ propeller for different lightweight materials under given Ocean environments by using Ansys Fluent 16.2. The conceptual design of the ship propeller is modeled with the help of CATIA. Fatigue life estimation on the rotor is a key and complex output of this work, so advanced methodology is mandatory for computation. For that purpose, the following advanced methodology has been implemented for this work, which is Hydro Structural Interaction (HSI) and Moving Reference Frame (MRF) techniques are associated in Computational Fluid Dynamics (CFD). Hydro-Fluid properties such as density and operating pressure are used as per the working vehicles’ environment, which has been easily, defined in Ansys Fluent 17.2. Thus this computational platform is perfect to handle hydrodynamic simulations, even though the gird convergence study is conducted for the better outcomes. In the case of structural simulation, the existing materials such as Aluminium alloy and Stainless Steel are used for fatigue life estimation under HSI loading conditions. Finally, the fatigue life estimation of Marine Vehicles’ propeller is extended for composite materials to compare the life of a rotor. Both the Hydrostatic and Hydrodynamic loading conditions are tested on Aquatic Vehicle’s rotor and thereby the suitable material is chosen and given to the future input for real-time applications.

Fatigue life estimation of clinched joints from wrought aluminium alloy with Local Strain Approach considering cold working of joining process

Mechanical clinching is an ef- ficient join- ing tech- nique fre- quently used in the au- tomotive industry to join sub- assemblies of the car body. Dur- ing me- chanical clinching, the ma- terial in the joint is cold worked altering the cyclic material proper- ties and affecting the per- formance of the joint under cyclic loading. The pa- per presents an approach for fatigue life es- timation of clinched joints us- ing the Local Strain Approach. Numer- ical sim- ulation is utilized to retrieve local stresses and strains in the crit- ical re- gion. Ex- perimen- tal inves- tigation is presented to vali- date the crack ini- tiation lo- cation and an assess- ment of the fa- tigue life estima- tion is car- ried out.