Title

"The automatic optimization of metal forming processes – Inverse identification of constitutive parameters for tubular materials based on hydraulic bulge test"

By

Bin Zhang

Abstract

Tube hydroforming process is an advanced manufacturing technology for complex thin-walled tubular components applied in the aerospace, aviation and automotive industries. The fluid medium is used as a pressure source to deform tubular materials into the desired shape in this process. Finite element model is a popular method to describe and analyze this innovative process. A successful tube hydroforming operation and reliable finite element simulation depend heavily on the accurate characterization of mechanical properties of the incoming tubular materials. As a result, it is critical to determine these material parameters utilizing suitable experimental tests and evaluation procedures.

This Ph.D. research presents the development of an automatic inverse parameter identification framework combining finite element models with gradient-based algorithms and its utilization in determining material parameters for thin-walled metallic tubes. The feasibility and performance of this proposed inverse framework are demonstrated through applying it to different tube hydraulic bulge tests with fixed and forced end-conditions to identify the flow stress data of thin-walled aluminium tubes. As a result of this research, it is possible to conclude that the novel strategy does not depend heavily on the initial points and can improve the computation robustness and identify more accurate constitutive parameters for tubular materials.

Assessment Committee   

• Associate professor Jens Henrik Andreasen (chairman), Department of Materials and Production, Aalborg University
• Professor Cheng Lu, University of Wollongong, Australia
• Associate Professor Jun Ma, Norwegian University of Science and Technology, Norway

Supervisor

• Associate professor Benny Ørtoft Endelt
  Department of Materials and Production, Aalborg University

Co-supervisor

• Karl Brian Nielsen, Department of Materials and Production, Aalborg University

The PhD defense will be hosted by Moderator associate professor Jens Henrik Andreasen. The lecture constitutes a 45 minutes presentation by Bin Zhang followed by a short break and a discussion session with questions from the opponents and the auditorium.

After the defense the department host a small reception in Fibigervej 14, common room.

Link for online participation