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User Defined FE Based Connector Joints For Plastics

CAEfatigue Ltd-Neil Bishop, Paresh Murthy
Hella GmbH & Co. KGaA-Thomas Thesing, Odo Karger
  • Technical Paper
  • 2020-01-0186
To be published on 2020-04-14 by SAE International in United States
Spot Welds are a category of joints used extensively in automotive structures, normally for metals. The fatigue analysis of such spot welds can be evaluated using (a) the Point 2 Point (P2P) method where a beam or bar is used to connect the 2 surfaces being joined, (b) a more modern approach where the 1D element is replaced with an “equivalent” brick element, or (c) a third approach falls somewhere between where a “spider” and circular ring of elements is used to represent the spot weld. In all three cases there is an assumption that the cross section is circular. For some specialist cases such as plastic connectors (Heat Stakes) a new user defined weld is proposed. This paper will describe the approach which is based on the concept that a user generated tensor line (equivalent to the theoretical Force/Moment to stress algorithms built into the P2P approach) can be used along with special S-N curves create for different Heat Stake shapes.
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Reducing Cycle Times of Refill Friction Stir Spot Welding in Automotive Aluminum Alloys

Brigham Young University-Brigham Larsen, Yuri Hovanski
  • Technical Paper
  • 2020-01-0224
To be published on 2020-04-14 by SAE International in United States
Refill friction stir spot welding (RFSSW) is an emerging welding process that has shown great potential in joining automotive and aerospace aluminum alloys. Though the process has been in development for nearly a decade, RFSSW has yet to see wide-scale implementation in the automotive industry. A major barrier, preventing RFSSW from use by manufacturers, is the long cycle time that has been historically associated with making a weld. In order for RFSSW to become a readily implementable welding solution, cycle times must be reduced to an acceptable level, similar to that of well developed, competing spot joining processes. In the present work, an investigation of the RFSSW process is conducted to evaluate factors that have traditionally prevented the RFSSW process from achieving fast cycle times. Within this investigation, the relationship between cycle time and joint quality is explored, as is the meaning and measurement of cycle time in the RFSSW process. Claims and general sentiment found in prior literature are challenged regarding the potential for high-speed RFSSW joints to be made. The RFSSW weld design—as…
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Coupled Weld-Rupture Analysis of Automotive Assemblies

ESI North America-Yogendra Gooroochurn, Ramesh Dwarampudi, Vijay Tunga
ESI US R&D-Megha Seshadri, Ravi Raveendra
  • Technical Paper
  • 2020-01-1076
To be published on 2020-04-14 by SAE International in United States
Lightweight driven design in the automotive industry and the push for Electric Vehicles mandate the use of innovative materials such as Steel (HSS, UHSS, AHSS) and Aluminum alloys. For steel suppliers to meet the strength requirements of high strength steels, they often alloy the steel chemistry (depending on mill capability, rolling capacity, quenching capacity, etc.). When used in welded assembly constructions, these steels, as compared to traditional steels, behave differently. Depending on the welding heat input, the material chemistry and thickness, they either harden or soften in the heat affected zone. Similar behavior is observed with the most commonly used aluminum alloys (5000 and 6000 series) in the automotive sector. For both alloy types, different strengthening mechanism are used to meet their initial strength requirements (by work hardening and by heat treating respectively) but they both undergo softening in the heat affected zone during welding. Regardless of the alloys, the material in the heat affected zone is affected and so is the performance of the weldment during service. FE analyzes of Welding and Performance have…
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Innovative additive manufacturing process for successful production of 7000 series aluminum alloy components using Smart Optical Monitoring System

SenSigma LLC-Jay Choi, Alex Rice
University of Michigan-Jyoti Mazumder
  • Technical Paper
  • 2020-01-1300
To be published on 2020-04-14 by SAE International in United States
Aircraft components are commonly produced with 7000 series aluminum alloys due to its weight, strength, and fatigue properties. Auto Industry is also choosing more and more aluminum component for weight reduction. Current additive manufacturing (AM) methods fall short of successfully producing 7000 series aluminum alloys due to the reflective nature of the material along with elements with low vaporization temperature. Moreover, lacking in ideal thermal control, print inherently defective products with such issues as poor surface finish alloying element loss and porosity. All these defects contribute to reduction of mechanical strength. By monitoring plasma with spectroscopic sensors, multiple information such as line intensity, standard deviation, plasma temperature or electron density, and by using different signal processing algorithm such as vector machine training or wavelet transforming, AM defects have been detected and classified. For composition analysis, the ratio of the maximum intensities of Mg(I)/Al(I) shows a strong trend with the amount of Zn and Mg in the powder, and the results are extremely promising regarding the ability to use the online spectra for real time determination…
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Spatially Optimized Diffusion Alloys: A Novel Multi-Layered Steel Material for Exhaust Applications

Arcanum Alloys Inc.-Zachary Detweiler, David Keifer, Daniel Bullard
Tenneco Inc.-Adam Kotrba, Tony Quan, Winston Wei
  • Technical Paper
  • 2020-01-1051
To be published on 2020-04-14 by SAE International in United States
A novel Spatially Optimized Diffusion Alloy (SODA) material has been developed and applied to exhaust systems, a very aggressive environment with high temperatures and loads, as well as excessive corrosion. Traditional stainless steels disperse chromium homogeneously throughout the material, with varying amounts ranging from 11% to 18% dependent upon its grade (e.g. 409, 436, 439, and 441). SODA steels, however, offer layered concentrations of chromium, enabling an increased amount along the outer surface for much needed corrosion resistance and aesthetics. This outer layer, approximately 70µm thick, exceeds 20% of chromium concentration locally, but is only 3% in bulk, offering selective placement of the chromium to minimize its overall usage. And, since this layer is metallurgically bonded, it cannot delaminate or separate from its core, enabling durable protection throughout manufacturing processes and full useful life. The core material may be of various grades, however, so this study employs interstitial free steel (low carbon), which offers not only commercial advantages, but also eases manufacturing operations, as it is more formable than stainless steel grades. The material and…
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Study the Influences of Weld Line on Mechanical Properties of Talc Filled PP

Ford Motor Company-Shiyao Huang, Patti Tibbenham, Lingxuan Su, Danielle Zeng, Jin Zhou, Xuming Su
University of Michigan-Ann Arbor-Mayme Philbrick
  • Technical Paper
  • 2020-01-1306
To be published on 2020-04-14 by SAE International in United States
Weld line can significantly reduce ultimate tensile strength (UTS) and fracture strain of talc filled PP. In this paper, two different injection molding tests were carried out. First, an injection mold with triangular inserts was built to study the influence of meeting angles on material properties at weld line region. Tensile samples were cut at different locations along the weld line on the injection molded plaques. The test results showed that both UTS and fracture strain increase when the sample locations are away from the weld line. This trend is attributed to different microstructures with respect to different meeting angles. Second, standard ASTM tensile bars with and without weld line were injection molded to identify the size of the weld line effect zone. A FEA model was built in ABAQUS, where the tensile sample was divided into two different regions, solid region and weld line effect region. Stress-strain relationships of the solid region were derived from tensile tests of solid bars, while the mechanical properties of weld line effect zones were characterized from samples with…
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Analytical model to predict the fatigue life of tubular welded structures subjected to compressive loading

American Axle & Manufacturing, Inc.-Anoop Vasu, Shizhu Xing, Jifa Mei, William Webster, Scott Jacob, Jerry Chung, Ravi Desai
  • Technical Paper
  • 2020-01-0185
To be published on 2020-04-14 by SAE International in United States
It has been well documented that welded components can fail under pure compression under fatigue loading conditions (R=-∞). Unlike non-welded components, the mean stress effect has shown to have little impact (Gurney, 1979). Currently, most weld prediction procedures does not involve mean stress effect and the relationship involves stress range (or strain range) plotted against the number of cycles to failure. Two case studies were performed to understand the mean stress effect of tubular welds. First case was weld under compressive pre-stress (caused by bolt pretension) subjected to tension and compressive loading. Second case was weld under no pre-stress subjected to the same tension and compressive loading. It was observed that the welds under compression for tubular structures (eg; an axle tube) demonstrated significant resistance to fatigue failure. Traction structural stress method has proven to be very effective for the fatigue life prediction of welded structures. However, the predictions for the two case studies considered in this research were under-predicting the fatigue life significantly. This paper propose an analytical model to capture the weld behavior…
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Fatigue Evaluation of Flow Drill Screw Joints Using the Equilibrium-Based Structural Stress Method

Engineering Mechanics Corp. of Columbus-Jeong Hong, Gery Wilkowski
  • Technical Paper
  • 2020-01-0189
To be published on 2020-04-14 by SAE International in United States
According to increasing the demands of light-weight design in the automotive industry, the usage of thinner and lighter materials such as aluminum alloy has led to significant weight reduction. The joining of these materials has required new technologies in joining/fastening rather than welding. Flow drill screw (FDS) is one of the latest technologies to fasten sheet metal panels. This paper discusses the results of an evaluation of the fatigue characteristics of FDS joints based on experimental data and observations from the literature. It was observed that the important geometric parameters of FDS joints are the gap between panels and the extruded (or bulged) zone during screwing. Major failure modes were observed as panel failure which cracks grow from the inner surface of the panel around the bulged zone. In this paper, the fatigue evaluation procedure for FDS joints using the mesh-insensitive equilibrium-based structural stress (ESS) method was proposed. The ESS-based simplified modeling procedure was used for the fatigue evaluation procedure development for FDS joints. The effectiveness and applicability of the ESS-based simplified procedure for modeling…
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Full Body Car Analysis in the Time and Frequency Domains - Sheet, Spot and Seam Weld Fatigue Benchmark Studies

CAEfatigue, Ltd.-Neil Bishop, Stuart Kerr
Desktop Engineering Ltd.-Andy Woodward
  • Technical Paper
  • 2020-01-0195
To be published on 2020-04-14 by SAE International in United States
The fatigue analysis of a full car body requires the sheet metal (sheet fatigue), spot welds (spot weld fatigue) and seam welds (seam weld fatigue) to be thoroughly evaluated for durability. Traditionally this has always been done (via separate processes) in the time domain but recently new techniques have been implemented to perform all of these tasks in the frequency domain with numerous advantages. This paper will summarize the frequency domain process and then compare the results (and performance) against the more usual time base result
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Crash Response of a Repaired Vehicle - Influence of Welding UHSS Members

University of Agder-Gulshan Noorsumar, Kjell Robbersmyr, Svitlana Rogovchenko, Dmitry Vysochinskiy
  • Technical Paper
  • 2020-01-0197
To be published on 2020-04-14 by SAE International in United States
Automakers generally recommend not to weld structural parts after a vehicle crash, and these should be replaced as a whole part in case of a crash event. Sectioning of these members is also not recommended and use of the repair manual is mandatory in case of fracture of such parts. However, repair shops may not adhere to these instructions and use incorrect repair procedures on these members which would modify their strength properties. This study analyses the impact of welding structural members in a vehicle like the A-pillar which use Ultra-High Strength Steels (UHSS) for reducing the weight of the vehicle and improving the crashworthiness of the structure. The research conducted in this paper highlights the differences in the crash performance of a repaired vehicle as opposed to baseline injury values for the vehicle. The performance of the modified vehicle when tested for different loadcases shows reduced crash performance as compared to the baseline performance and it can be concluded that welding or sectioning the UHSS parts would influence the crashworthiness of a vehicle. This…