Session: 01-07: Nonlinear Problems in Aerospace Structures

Paper Number: 125708

125708 - On the Implementation of Viscoplastic Models in an Open Source Finite Element Code (Calculix) 

The numerical finite element simulation of viscoplastic phenomena is very challenging as it involves complex non-linear phenomena. Isotropic and kinematic strain hardening could occur simultaneously in the structural component, making even more difficult the convergence in the numerical analysis. The adoption of open source numerical codes has several advantages over the commercial ones, such as: flexibility, cost efficiency, the possibility to test the open-source software on a smaller scale and, then, move to commercial codes for bigger scales. However, differently from commercial codes (e.g. Ansys, Abaqus, etc.), state of the art hardening numerical models are currently not available in open source finite element codes. This work aims at implementing in the open source code considered non-linear isotropic and kinematic hardening as well as creep models, in order to represent the thermo-mechanical behavior of the cooling channel of liquid rocket engine thrust chamber. To this end a user material model has been implemented in the open source code CalculiX, obtaining results in a very good accordance with those obtained adopting a finite element commercial code (Ansys). Furthermore, three damage models have been also considered in the use material subroutine to consider the effects of thermal ratcheting (ductile failure), low cycle fatigue and creep.

Presenting Author: Michele Ferraiuolo CIRA

Presenting Author Biography: Michele Ferraiuolo took his degree in Mechanical Engineering in 2002 at the Second University of Naples. He is now a Research engineer at the Italian Aerospace Research Centre (CIRA). The main topic of his work is the Re-entry vehicle’s Hot Structures design. Moreover, in the frame of the PhD studies, he has developed new thermostructural design methodologies in order to decrease the computational time needed to perform a complete design of the thermal structures.
Recently he has worked on the Stress Analysis on the structural components of an Unmanned Aerial vehicle. From 2010 he is responsible for the Mechanical and Material Processes for the Hyprob-Bread Project, whose main goal is to design build and test a 30 kN regeneratively cooled thrust chamber. From February 2015 he is head of the “Technologies and design of hot structures and thermal control” lab. under the Materials and Structures department.