Dual-Function Fixture Design for Dynamic Testing of Automotive Bumper/Crash-Box Case Study Utilizing Friction Stir Welding
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DUAL-FUNCTION FIXTURE DESIGN FOR DYNAMIC TESTING OF AUTOMOTIVE BUMPER/CRASH-BOX CASE STUDY UTILIZING FRICTION STIR WELDING Thesis by Alan Bruce Handyside Bachelor of Science, Wichita State University, 1991 Submitted to the Department of Mechanical Engineering and the faculty of the Graduate School at Wichita State University in partial fulfillment of the requirements for the degree of Master of Science May 2011 © Copyright 2011 by A. Bruce Handyside All Rights Reserved DUAL-FUNCTION FIXTURE DESIGN FOR DYNAMIC TESTING OF AUTOMOTIVE BUMPER/CRASH BOX CASE STUDY UTILIZING FRICTION STIR WELDING The following faculty members have examined the final copy of this thesis for form and content, and recommend that it be accepted in partial fulfillment of the requirement for the degree of Master of Science in Mechanical Engineering. ___________________________________ Hamid Lankarani, Committee Chair ___________________________________ George Talia, Committee Member ___________________________________ Dwight Burford, Committee Member iii DEDICATION To my wife Sanua, my sons Neal and Christopher, and my deceased mother, who encouraged me to follow my dream iv ACKNOWLEDGEMENTS I would like to thank my advisor, Dr. Hamid Lankarani, for his assistance, support and guidance. I also thank Dr. Dwight Burford, Director of the Advanced Joining and Processing Laboratory at the National Institute for Aviation Research (NIAR) for the opportunity to work and learn in the friction stir welding lab at Wichita State University (WSU). I would like to thank all the people in the Advanced Joining and Processing Laboratory who made tensile coupons, macros of friction stir welds (FSW), drilled holes, and assembled details of this test fixture. I also thank the WSU Impact Dynamics Laboratory for supporting this activity and the WSU machine shop and facilities people for providing expert workmanship. I would like to thank fellow team member, Farzad Baratzadeh, who, with our team, coauthored the discontinuous weld paper, which is a precursor to this thesis. I also thank fellow team member, Jeff Buller, who was indispensible by developing the clamping, optimum weld parameters and accomplishing the friction stir welding for the fixture frame. This study is funded through the Center for Friction Stir Processing (CFSP), a University/Industry Cooperative Research Center under the National Science Foundation. Dr. Burford is Director for the Wichita State University site membership. This thesis would not have been possible without funding from WSU sponsors such as Bombardier, Cessna, Embraer, General Motors, Hawker Beechcraft, and the FAA. A special thanks to Dr. Blair Carlson, who was our primary General Motors (GM) collaborator, Mr. Bob Szymanski of GM for helping us obtain material and the GM Management for their vision regarding the case study for which this test fixture was designed. v ABSTRACT Recent advancements in friction stir welding (FSW) technology and pin (probe) tool design for aluminum have made FSW applications in aerospace and automotive structures quite attractive. FSW has the potential for better fit, form and function when compared to fusion welding. The aim of this research was to design, develop and fabricate a fixture to meet the requirement of a standard automotive impact test on an FSW bumper/crash-box assembly. A fusion welded bumper/crash-box design was provided to Wichita State University (WSU) by the General Motors Corporation (GM). For this case study, the bumper design was not changed, but the existing crash box was altered to satisfy two FSW assembly designs, incorporating unique lap and hybrid welds for the closeout area at each end of the bumper. Both designs use a common butt weld along a nested interface between the crash box and the bumper. The goal of this test fixture was to facilitate a dynamic vehicle test on FSW bumpers and compare the test results to that of fusion-welded bumpers. Functional use of FSW in bumper design was to be determined through this case study. Since the test fixture uses similar type welds as the bumper geometry, FSW was also incorporated into the test fixture design. Several design constraints related to vehicle testing, FSW and the University Impact Laboratory were met. Process simulation of dynamic forces on the bumper and test fixture welds, along with standard static analysis, were used for design verification. Parameter bounding and test coupons of FSW in aluminum were used to determine parent and weld material properties as well as optimum weld parameters for manufacturing the test fixture. Aluminum alloys 6063-T6, 6061-T6, 7050-T7451, concrete and structural fusion welded steel were selected for materials in the test fixture design. A linear bearing rail system was used to facilitate the gravity-fed drop tower and dynamically fed sled test functions. vi TABLE OF CONTENTS Chapter Page 1. INTRODUCTION ...............................................................................................................1 1.1 Background ..............................................................................................................1 1.1.1 Friction Stir Welding History ......................................................................1 1.1.2 Vehicle Impact Testing History ...................................................................1 1.1.3 Wichita State University NIAR History ......................................................2 1.2 Advantages of FSW ................................................................................................4 1.3 Design Research Objective ......................................................................................4 2. LITERATURE REVIEW ....................................................................................................5 2.1 Impact Test Standards and Types ............................................................................5 2.1.1 Vehicle Tests ................................................................................................5 2.1.2 Pendulum .....................................................................................................5 2.1.3 Barrier ..........................................................................................................6 2.1.4 Drop Tower ................................................................................................10 2.2 Friction Stir Welding .............................................................................................12 2.2.1 Process Concept .........................................................................................12 2.2.2 Friction Stir Welding Tools .......................................................................14 2.2.3 Threaded Counter Flow Tool .....................................................................15 2.2.4 Basic Types of Friction Stir Welded Joints ...............................................16 2.2.5 Butt Joints ..................................................................................................17 2.2.6 Metallurgy of Friction Stir Welding ..........................................................19 2.3 Aluminum Alloys...................................................................................................21 2.3.1 General Information (Characteristics and Classification) ..........................21 2.3.2 Property Values for Aluminum Alloy 6063-T6 .........................................24 2.3.3 Property Values for Aluminum Alloy 6061-T6 .........................................24 2.3.4 Property Values for Aluminum Alloy 6082-T6 .........................................24 2.3.5 Property Values for Aluminum Alloy 7075-T6 .........................................25 2.3.6 Property Values for Aluminum Alloy 7050-T7451 ...................................26 2.4 Structural Steel .......................................................................................................26 2.4.1 General Information (Description and Applications) ................................26 2.4.2 Property Values for A36 (A500) Structural Steel ......................................27 2.4.3 Property Values for 1566 Steel ..................................................................28 2.5 Structural Concrete ................................................................................................29 2.5.1 General Information (Description and Applications) ................................29 2.5.2 Strengthening Methods (Concrete and Rebar) ...........................................29 2.5.3 Property Values (Concrete and Rebar) ......................................................30 2.5.4 Reinforcement Analysis Properties............................................................33 vii TABLE OF CONTENTS (continued) Chapter Page 3. FIXTURE DESIGN STUDY OBJECTIVE, CONSTRAINTS AND CONCEPTS ..........34 3.1 Fixture Design Study Objectives ...........................................................................34 3.1.1 GM Bumper Case Study Objective............................................................34 3.1.2 Fixture Design Study Objective .................................................................38 3.2 Fixture Design Study Constraints .........................................................................38 3.2.1 GM Constraints ..........................................................................................38 3.2.2 Drop Test and Impact Test Constraints .....................................................39 3.2.3 WSU and Impact Facility Constraints