13th International Conference on the Technology of Plasticity (ICTP 2021): Residual Stresses in Metal Forming II
Program Organizers: Glenn Daehn, Ohio State University; Libby Culley, The Ohio State University; Anupam Vivek, Ohio State University; Jian Cao, Northwestern University; Brad Kinsey, University of New Hampshire; Erman Tekkaya, TU Dortmund; Yoshinori Yoshida, Gifu University
Thursday 10:20 AM
July 29, 2021
Room: Virtual: Room B
Location: Virtual
Session Chair: Erman Tekkaya, TU Dortmund
Analysis of the Influence of Joining Partners on the Residual Stress Distribution in Assembled Shafts: Christina Guilleaume1; Alexander Brosius2; 1TU Dresden; 2Institute of Forming Technology and Lightweight Construction Institute
In this paper the influence of joining partners like gear wheels on the residual stress distribution of an assembled shaft is analyzed using numerical FE-analysis as well as experimental verification. The joint is formed by a cross rolling process that uses two sets of opposing work rolls to push shaft material towards the joining partner, thereby forming a force and form closure. Previous work has shown that the residual stress distribution in the notch that is formed by this rolling process has a significant influence on the fatigue life of the shaft (42CrMo4) when submitted to cycling loads. In the experimental investigations strain gauges applied to the joining partners will be used to measure the resulting forces in the joint section and numerical analysis will be used to analyze the resulting stress distribution in the entire part. Different material and geometric combinations will be tested and analyzed.
Experimental and Numerical Investigations on the Development and Stability of Residual Stresses Arising from Hot Forming Processes: Bernd-Arno Behrens1; Jörg Schröder2; Hendrik Wester1; Dominik Brands2; Sonja Uebing2; Christoph Kock1; 1Institue of Forming Technology and Machines; 2Institut für Mechanik
Residual stresses are an important issue as they affect both the manufacturing process as well as the performance of the final parts. Taking into account the whole process chain of hot forming, the integrated heat treatment provided by a defined temperature profile during cooling of the parts offers a great potential for targeted adjustment of the desired residual stress state. The aim of this work is the investigation of technological reproducibility and stability of residual stresses arising from the thermomechanical forming process. For this purpose, a long-term study of residual stresses on hot formed components is conducted. In order to develop finite element models for hot forming, a comprehensive thermomechanical material characterisation with special focus on phase transformation effects is performed. The numerical model is validated by means of a comparison between residual stress states determined with X-ray diffraction on experimentally processed components and predicted residual stresses from the simulations.
Investigations and Improvements in 3D-DIC Optical Residual Stress Analysis – A New Temperature Compensation Method: Frederik Dahms1; Werner Homberg1; 1Paderborn University
With the follow-up objective of measuring and generating defined residual stress distributions in aluminium flanges formed by friction-spinning of tubes, this paper proposes residual stress measurement by linear guided translation of the specimen between hole-drilling and 3D-DIC image capturing process. The procedural benefit is the usage of an ideal camera calibration, respectively the angle between the cameras and the specimen, which leads to an optimal depth of field with a wide range measuring surface around the drill hole. Influences of the linear guided displacement of the specimen on the measuring accuracy were determined to be tolerably low. The measurement of heating curves in the illuminated measuring process proves a thermal induced systematically error. Therefore, a mathematical approach for subtraction of thermal induced strain is proposed. The obstruction of heat dissipation by the speckle pattern coating is also considered. Additionally, solutions for external influences like airflow and vibration are applied.
Influence of Shear Cutting Process Parameters on the Residual Stress State and the Fatigue Strength of Gears: Daniel Mueller1; Jens Stahl2; Isabella Pätzold2; Roland Golle2; Thomas Tobie1; Wolfram Volk2; Karsten Stahl1; 1Institute of Machine Elements (FZG), Technical University of Munich; 2Chair of Metal Forming and Casting (utg), Technical University of Munich
Shear cutting is used for manufacturing parts ranging from e.g. washers to complex gears. The latter are typically subjected to cyclic loading and fail foremost due to fatigue damages. In this paper, the influence of the process parameters on the residual stress state and the resulting bending fatigue strength are addressed. To simulate the bending stress occurring in the tooth root, C-shaped specimens were manufactured by different blanking processes. The die-clearance and punch and die edge radii were varied with these blanking techniques. After measuring the cut-surface geometry, the hardness distribution and the surface roughness, the fatigue strength was determined in a pulsating test rig. By carrying out residual stress measurements using x-ray diffraction and simulating the material flow behavior using the Finite-Element-Method, basic mechanisms, which are influencing the residual stress state and the resulting bending fatigue strength, were identified and will be presented and discussed in the paper.
Cancelled
Impulse-based Residual Stress Relief: Bhuvi Nirudhoddi1; Anupam Vivek1; Glenn Daehn1; 1Ohio State University
Recent impulse calibration studies have provided some insight into the mechanism of shock induced springback relief. The driving hypothesis for this physical phenomenon is that modest shockwaves relieve elastic residual stresses and result in net shape conformance. Calibration experiments were performed using the Vaporizing Foil Actuator (VFA) method to further understand this mechanism. The VFA method was used to deliver 1-3 GPa pressure waves to change the curvature of pre-strained aluminum workpieces to a fully flat shape. It is speculated that the change in shape is a consequence of elastic stress relief caused by the propagation of planar shockwaves. A mechanics and shock physics based theory for shockwave interaction with residual stresses is proposed. Preliminary pressure estimates were performed using a Photon Doppler Velocimeter and the Profile Indentation Pressure Evaluation (PIPE) method.