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Research on Joining High Pressure Die Casting Parts by Self-Pierce Riveting (SPR) using Ring-Groove Die Comparing to Heat Treatment Method

Bollhoff Inc.-Xuzhe Zhao
Chang’an University-Dean Meng
  • Technical Paper
  • 2020-01-0222
To be published on 2020-04-14 by SAE International in United States
Nowadays, the increasing number of structural high pressure die casting (HPDC) aluminum parts need to be joined with high strength steel (HSS) parts in order to reduce the weight of vehicle for fuel-economy considerations. Self-Pierce Riveting (SPR) has become one of the strongest mechanical joining solutions used in automotive industry for the past several decades. Joining HPDC parts with HSS parts can potentially cause joint quality issues, such as joint button cracks, low corrosion resistance and low joint strength. The appropriate heat treatment will be suggested to improve SPR joint quality in terms of crack reduction. But the heat treatment can also result in the blister issue and extra time and cost consumption for HPDC parts. The relationship between the microstructure of HPDC material before and after heat treatment with the joint quality is going to be investigated and discussed for interpretation of cracks initiation and propagation during riveting. The SPR joint quality will be evaluated based on interlock distance, the minimum remaining thickness (Tmin), shear strength etc. Instead of using heat treatment method, the…
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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 welds 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 that falls somewhere between where a “spider” and circular ring of elements, is used to represent the spot weld. In all 3 cases there is an assumption that the cross section is circular. For some specialist cases such as plastic connectors, the cross section is not circular so a new user defined weld is proposed. This paper will describe the approach that is based on the concept that a user generated tensor line can be used (equivalent to the theoretical Force/Moment to stress algorithms built into the P2P approach) along with special S-N curves create for different joint 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
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 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 described by process parameters such as tool feed rate, tool rotational velocity, and plunge depth- is shown through experimentation to affect the loads and torques placed on RFSSW tooling and machines during the welding process. As cycle time is decreased, the load and torque on the…
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Development of a New High Orientation Paint System to Achieve Outstanding Real Metallic Designs

Toyota Motor Corporation-Takao Tsukimori
  • Technical Paper
  • 2020-01-0899
To be published on 2020-04-14 by SAE International in United States
Silver metallic colors with thin and smooth aluminum flake pigments have been introduced for luxury brand OEMs. Regarding the paint formulation for these types of colors, low non-volatile(NV) and high aluminum flake pigment contents are known as technology for high metallic appearance designs. However, there are two technical concerns. First is mottling which is caused by uneven distribution of the aluminum flake pigments in paint film and second is poor film property due to high aluminum pigment concentration in paint film. Therefore, current paint systems have limitation of paint design. As a countermeasure for those two concerns, we had investigated cellulose nanofiber (CNF) dispersion liquid as both the coating binder and rheology control agent in a new type of waterborne paint system. CNF is an effective rheology control agent because it has strong hydrogen bonds with other fiber surfaces in waterborne paint. The CNF shows similar viscosity result with conventional water borne paint though CNF contents is less than 1wt% and NV is less than 5wt%. Furthermore, CNF's surface bonds with isocyanate resin makes strong…
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Parameter Sensitivity Study of Self-piercing Rivet Insertion Process using Finite Element and Machine Learning Method

Chongqing University-Yudong Fang, Zhenfei Zhan
Ford Motor Company-Li Huang, Shiyao Huang
  • Technical Paper
  • 2020-01-0219
To be published on 2020-04-14 by SAE International in United States
Self-piercing rivets (SPR) are efficient and economical joining methods for lightweight automotive body structure manufacturing. Finite element method (FEM) is a potential effective way to assess joining process while some uncertain parameters can be employed in the simulation based on the prior knowledge, which could lead to significant mismatches between CAE predictions and physical tests. Thus, a sensitivity study on critical CAE parameters is important to guide the high-fidelity modeling of SPR insertion Process. In this paper, a 2-D symmetrical CAE model is constructed to simulate the insertion process of the SPR using LS-DYNA/explicit. Then, several surrogate models are trained using machine learning methods to build the linkage between selected inputs (e.g. material properties, interfacial frictions, clamping force) and outputs (cross-section dimensions). It is found that it is feasible to train surrogate models with high accuracy to replace the time-consuming CAE simulations with a limited sampling volume. Based on trained surrogate models, an extensive sensitivity study is conducted to thoroughly understand the impact of a collection of CAE parameters. This research provides a solid foundation…
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A Crack Detection Method for Self-Piercing Riveting Button Images through Machine Learning

Chongqing University-Ling Jiang, Xuyang Wang, Zhenfei Zhan
Ford Motor Company-Li Huang, Shiyao Huang, Garret Huff, Amanda Freis
  • Technical Paper
  • 2020-01-0221
To be published on 2020-04-14 by SAE International in United States
Self-piercing rivet (SPR) joints are a key joining technology for lightweight materials, and they have been widely used in automobile manufacturing. Manual visual crack inspection of SPR joints could be time-consuming and relies on high-level training for engineers to distinguish features subjectively. This paper presents a novel machine learning-based crack detection method for SPR joint button images. Firstly, sub-images are cropped from the button images and preprocessed into three categories (i.e., cracks, edges and smooth regions) as training samples. Then, the Artificial Neural Network (ANN) is chosen as the classification algorithm for sub-images. In the training of ANN, three pattern descriptors are proposed as feature extractors of sub-images, and compared with validation samples. Lastly, a search algorithm is developed to extend the application of the learned model from sub-images into the original button images. The preliminary results on non-cracked and cracked button images show that the proposed crack detection method is an effective approach to identify a potential defect.
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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 the increasing demands for light-weight design in the automotive industry, the use of thinner and lighter materials such as aluminum alloys for automotive parts has led to significant weight reduction. The joining of these materials has required development of new technologies in joining/fastening rather than welding. Flow drill screwing is one of the latest technologies created to fasten sheet metal panels.This paper discusses results of an evaluation of fatigue characteristics of flow drill screw (FDS) joints based on experimental data and observations from the literature. It was observed that the important fatigue-related geometric parameters of FDS joints were the gap between sheets and the extruded (or bulged) zone during screwing. Major failure modes were observed such as sheet failures where cracks grow from the inner surface of the sheet and around the extruded zone.In this paper, the fatigue evaluation procedure for FDS joints using the mesh-insensitive equilibrium-based structural stress (ESS) method was used. The ESS-based simplified modeling procedure was used for the fatigue-evaluation procedure for FDS joints. The effectiveness and applicability of the…
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Analysis of Sheet Metal Joining with Self-Piercing Riveting

Oakland University-Srecko Zdravkovic, Sergey Golovashchenko
  • Technical Paper
  • 2020-01-0223
To be published on 2020-04-14 by SAE International in United States
Self-piercing riveting (SPR) has been in production in automotive industry since early 1990s. A substantial amount of experimental work was traditionally required in order to find an appropriate combination of rivet and anvil design to satisfy the required joint parameters. Presented study is describing the methodology of numerical simulation of SPR process and its experimental validation for Aluminum alloys and steels. Among material properties, the required information for numerical simulation includes stress-strain curves validated for the range of strains taking place in SPR process (up to 2.0 of true strain for sheets and up to 0.4 of true strain for the rivet) and parameters of fracture model for all involved materials: all sheets in the stack and the rivet material. Experimental data on stress-strain curves for extended range of strains was obtained based upon multistep rolling tensile testing procedure for the sheet metals. Parameters of the fracture model for sheets were defined by custom hole expansion test, and the parameter of the fracture model for the rivet was defined via expanding the tubular portion of…
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Development of Exmani-Heat protector to Improve Sound Absorption using New Perforated Thin Aluminum Plate

Hyundai Motor Group-Jaegi Sim, Minsoo Kim, KwangMin Yoon
  • Technical Paper
  • 2020-01-0405
To be published on 2020-04-14 by SAE International in United States
This technology is a technology for reducing the gas flow noise generated from the noise of the vehicle, especially the exhaust system. The primary function of the heat protector is thermal shutdown. However, due to the increase in engine power, downsizing of engines, and the rise of consumer's eye level, solutions about noise are now emphasized. Established the manufacturing technology of 3-ply composite board which can absorb sound in the existing heat protector. For this purpose, mold technology for punching aluminum sheet, optimization technique for punching effect, unique high-strength / high-forming pattern design, sound absorbing material selection and composite sheet molding technology, and noise vibration reduction mounting technology for plate joining were developed.
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Hybrid Forming - A Novel Manufacturing Technique for Metal-LFT Structural Parts

University of Siegen-Daniel Heidrich, Tobias Kloska, Xiangfan Fang
  • Technical Paper
  • 2020-01-0235
To be published on 2020-04-14 by SAE International in United States
Hybrid structural parts combining aluminum or steel sheets with long glass fiber reinforced thermoplastics (LFT) offer a great opportunity to reduce component weight for automotive applications. But due to high manufacturing cost, metal-LFT hybrid components are still scarcely used in automotive large-scale production. Thus in this work a novel cost- and time efficient manufacturing process for simultaneous metal sheet forming and compression molding of long fiber reinforced thermoplastics to manufacture automotive lightweight components is presented. In this manufacturing process, which is referred to as “Hybrid forming”, a fiber reinforced thermoplastic melt is used as a forming medium in the manner of well-known hydroforming processes. After forming the metal sheet by polymer melt in combination with the rigid die, the melt solidifies and forms a local reinforcement structure in the hybrid component. Since the metal sheet is pre-coated with a bonding agent prior to the forming process, a firmly bonded connection between metal and LFT can be achieved.For proof of concept a longitudinal control arm in a multi-link rear axle is chosen. By utilizing Hybrid forming…