Mikkel Melters Pedersen

Comparison of Post Weld Treatment of High Strength Steel Welded Joints in Medium Cycle Fatigue

This paper presents a comparison of three post-weld treatments for fatigue life improvement of welded joints. The objective is to determine the most suitable post-weld treatment for implementation in mass production of certain crane components manufactured from very high-strength steel. The processes investigated are: burr grinding, TIG dressing and ultrasonic impact treatment. The focus of this investigation is on the so-called medium cycle area, i.e. 10 000–500 000 cycles and very high stress ranges. In this area of fatigue design, the use of very high-strength steel becomes necessary, since the stress range can exceed the yield-strength of ordinary structural steel, especially when considering positive stress ratios (R > 0). Fatigue experiments and qualitative evaluation of the different post-weld treatments leads to the selection of TIG dressing. The process of implementing TIG dressing in mass production and some inherent initial problems are discussed. The treatment of a few critical welds leads to a significant increase in fatigue performance of the entire structure and the possibility for better utilization of very high-strength steel.

AAU-BOT1: a platform for studying dynamic, life-like walking

This paper describes the development of the humanoid robot AAU-BOT1. The purpose of the robot is to investigate human-like walking and in this connection, test prosthetic limbs. AAU-BOT1 has been designed with modularity in mind making it possible to replace, e.g. the lower leg to test transfemoral or transtibial prosthesis or orthosis. Recorded motion data from a male test person, along with approximated inertial and mass properties, were used to determine necessary joint torques in human walking which was used as design parameters for the robot. The robot has 19 degrees of freedom DoF, 17 actuated and 2 unactuated acting as passive toe joints. The project was granted 60,000 Euro, and to keep development costs below this, the development and instrumentation was carried out by three groups of master students from the Department of Mechanical Engineering ME and the Department of Electronic Systems at Aalborg University and supported by the Department of Health Sciences and Technology HST. To further reduce the cost, the robot uses off-the-shelf hardware which also reduced the time from idea to practical implementation. The result is a low-cost humanoid robot fully assembled and equipped with sensors ready to take its first steps.

A Cost-Effective Approach to Hardware-in-the-Loop Simulation

This paper presents an approach for developing cost effective hardware-in-the-loop (HIL) simulation platforms for the use in controller software test and development. The approach is aimed at the many smaller manufacturers of e.g. mobile hydraulic machinery, which often do not have very advanced testing facilities at their disposal. A case study is presented where a HIL simulation platform is developed for the controller of a truck mounted loader crane. The total expenses in hardware and software is less than 10.000

Re-analysis of fatigue data for welded joints using the notch stress approach

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