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Comparison of Different Methods for Panel Dent Resistance Using Numerical Assessment and Influence of Materials Used in Automotive Industry

Tata Technologies Ltd.-Ashish Sathaye, Deepak Srivastava, Manivasagam Shanmugam
  • Technical Paper
  • 2020-01-0483
To be published on 2020-04-14 by SAE International in United States
Conventionally, the automotive outer panels, giving vehicle its shape, have been manufactured from steel sheets. The outer panels are subjected to loads due to wind loading, palm-prints, person leaning on the vehicle, cart hits, and hail stones for example. Consumer awareness about these two panel characteristics: Oilcanning and Dent resistance is increased, which has been observed in recent marketing studies. Apart from perceptive quality, another factor depending on the dent performance is insurance and respective cost implications. Dents can occur due to several reasons such as object hits, parking misjudgement, hail stones etc. Phenomenon can be divided into two types, static and dynamic denting. Static dent case covers scenario wherein interaction with outer panel is mostly quasi-static. Hail stones present dynamic case where object hits a panel with certain kinetic energy. Automotive companies usually perform static dent assessment to cover all the cases. The scope of this paper is to discuss the comparison between two methods and its results using Finite Element Analysis. Influence of panel stiffness on dent resistance is also studied. Panel dent…
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Experimental Investigation of Axial Cutting of AA6061 Extrusions under a Tension Deformation Mode

University of Windsor-Anthony Gudisey, William Altenhof, John Magliaro
  • Technical Paper
  • 2020-01-0206
To be published on 2020-04-14 by SAE International in United States
A plethora of applications in the transportation industry for both vehicular and roadside safety hardware, especially seatbelts, harnesses and restraints, rely on tensile loading to dissipate energy and minimize injury. There are disadvantages to the current state-of-the-art for these tensile energy absorbers, including erratic force-displacement responses and low tensile force efficiencies (TFE). Axial cutting was extensively demonstrated by researchers at the University of Windsor to maintain a stable reaction force, although exclusively under compressive loading. A novel apparatus was investigated in this study which utilized axial cutting under a tensile loading condition to absorb energy. A parametric scope was chosen to include circular AA6061 extrusions in both T4 and T6 temper conditions with an outer diameter of 63.5 mm and wall thickness of 3.18 mm. The experiments were performed quasi-statically utilizing a custom, hydraulically powered long stroke tension/compression testing machine with a maximum capacity of 300kN. Strain-gauge based load cells and non-contact displacement transducers were implemented to measure the cutting force and displacement response of the setup. The results demonstrated highly stable force responses, with…
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Searching for Optimal Solutions for Motor Performance Design

Honda R&D Co.,Ltd.-Yuko Miyabe, Masahito Kakema, Toshihiro Saito
  • Technical Paper
  • 2020-01-0460
To be published on 2020-04-14 by SAE International in United States
This paper relates a method for seeking Pareto solutions for strength, torque-rotational speed characteristics, losses, and exciting force in the preliminary design of interior permanent magnet synchronous motors (IPMSM) and carrying out optimal design in an integrated manner. As to the constraint on strength, it was determined that the von Mises stress on the rotor core with respect to the load of the centrifugal force at 1.2 times the maximum rotational speed should not exceed the breaking strength of common electrical steel sheet material. As to the torque-rotational speed characteristic, this was determined to be the maximum torque for each rotational speed, taking into account the maximum voltage and current input when maximum torque per ampere control and field weakening control are applied. The maximum torque at low rotational speed and the maximum power at maximum rotational speed were taken as evaluation parameters. Losses were defined as the total value of DC copper loss occurring in the coil and iron loss occurring in the stator and rotor core. As to the exciting force, the 6th…
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Influence of Weld Lines on the Mechanical Properties of Talc Filled Polypropylene

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 lines can significantly reduce ultimate tensile strength (UTS) and fracture strain of talc filled polypropylene (PP). In this paper, two different injection molding tests were completed. First, an injection mold with triangular inserts was built to study the influence of meeting angles on material properties at the 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 insert. This trend is attributed to different meeting angles. Second, standard ISO tensile bars with and without weld line were injection molded to identify the size of the weld line affected zone. A FEA model was built in ABAQUS, where the tensile sample was divided into two different regions, the solid region and the weld line affected region. Stress-strain relationships of the solid region were derived from tensile tests of solid bars, while the mechanical properties of weld line affected zones were characterized from the weld line samples using…
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Experimental and Analytical Study of Drawbead Restraining Force for Sheet Metal Drawing Operations

Oakland University-Natalia Reinberg, Ashutosh Mokashi, Saeid Nasheralahkami, Sergey Golovashchenko, Srecko Zdravkovic, Yurdaer Demiralp
  • Technical Paper
  • 2020-01-0753
To be published on 2020-04-14 by SAE International in United States
Design of sheet metal drawing processes requires accurate information about the distribution of restraining forces, which is usually accomplished by a set of drawbeads positioned along the perimeter of the die cavity. This study is targeting bringing together the results of finite element analysis and experimental data in order to understand the most critical factors influencing the restraining force. The experimental study of the restraining force was performed using drawbead simulator tool installed into a tensile testing machine. Based upon the experimental results, it was observed that the restraining force of the given drawbead configuration is dependent upon the depth of bead penetration, friction between the drawbead surfaces as well as the clearance between the flanges of the drawbead simulator. This clearance is often adjusted during stamping operations to increase or decrease material inflow into the die cavity without any modification in the die. Numerical simulation was performed with Autoform software following the geometry of the experimental drawbead tools used in this study. Two different surface conditions were used in the experimental tools: surface treatment…
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Structural Performance Comparison between 980MPa Generation 3 Steel and Press Hardened Steel Applied in the Body-in-White A and B-Pillar Parts

General Motors LLC-Andre Pereira, Adam Ballard, Rajmouli Komarivelli, Haoming Li
United States Steel Corp.-Vasant Pednekar, Guofei Chen
  • Technical Paper
  • 2020-01-0537
To be published on 2020-04-14 by SAE International in United States
Commercially available Generation 3 (GEN3) advanced high strength steels (AHSS) have inherent capability of replacing press hardened steels (PHS) using cold stamping processes. 980 GEN3 AHSS is a cold stampable steel with 980 MPa minimum tensile strength that exhibits an excellent combination of formability and strength. Hot forming of PHS requires elevated temperatures (> 800°C) to enable complex deep sections. 980 GEN3 AHSS presents similar formability as 590 DP material, allowing engineers to design complex geometries similar to PHS material; however, its cold formability provides implied potential process cost savings in automotive applications. The increase in post-forming yield strength of GEN3 AHSS due to work and bake hardening contributes strongly toward crash performance in energy absorption and intrusion resistance. The viability of using cold stamped 980 GEN3 AHSS as a replacement for PHS has often been challenged due to concerns about formability and capability to meet final crash performance targets. To address these concerns, A-pillar and B-pillar parts were successfully cold stamped using U. S. Steel 980 GEN3 AHSS and assembled in a prototype mid-size…
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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 a Novel Test System to Determine the Durability of RTV Gasket Material

FCA US LLC-Wensheng Zhang, Erich Gernand
Oakland University-Bingxu Wang, Gary Barber, Na Lyu
  • Technical Paper
  • 2020-01-1069
To be published on 2020-04-14 by SAE International in United States
This paper describes a laboratory-based test system and procedure for determining the durability of RTV sealant with fretting movement. A test machine is described in which shear and tensile stress-generating displacements at room temperature and temperature of 100°C are produced to load an RTV seal. The test system utilizes an air pressurized hollow cylinder with a cap sealed by RTV sealant on a reciprocating test rig. An external air leakage monitoring system detects the health of the tested RTV seal. When air leakage occurs, the seal is determined to have failed. RTV sealant used in the test was fully cured at room temperature and then aged with engine oil. In the experiments, a total of 6 displacements were used to generate cycle/amplitude graphs for both shear and tensile modes. Failures were determined to be caused by the loss of adhesion in tensile mode, and by crack nucleation due to the special step design in shear mode. The results have validated the feasibility of the proposed test system and procedure, which can be used for durability…
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Durability Study of Automotive Additive Manufactured Specimens

Colorado Photopolymer Solutions-Amelia Davenport, Neil Cramer
Eastern Michigan University-Forough Zareanshahraki
  • Technical Paper
  • 2020-01-0957
To be published on 2020-04-14 by SAE International in United States
The long-term weathering behavior of three different 3D printable, non-stabilized, UV cure resin formulations (A and B with thiol-ene base, and C with acrylate chemistry) was studied using tensile testing, nano-indentation, and photoacoustic infrared (FTIR-PAS) spectroscopy. To this end, type I tensile bars were printed from each resin system using a 3D printer, and were post UV-cured under a broad spectrum source. Systems A and C showed a similar trend after weathering. They first experienced an increase in modulus and tensile strength, due to additional crosslinking of the residual unreacted species. This increase in mechanical properties was followed by a drop in modulus, tensile strength, and percent elongation, due to the over-crosslinking and consequent embrittlement. System B, however, showed remarkable retention of the mechanical properties before/after weathering. Nano-indentation results were in good agreement with the tensile properties, showing a similar trend in hardness variations. Although Systems A and C outperformed System B in photooxidation performance, all three systems demonstrated promising results considering no hindered amine light stabilizers (HALS) were used in the formulations. Both photooxidation…
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Fuel Tank Dynamic Strain Measurement Using Computer Vision Analysis

Ford Motor Company-Ram Krishnaswami
Fusion Engineering-Mark Fleming, Kunihiro Nakamoto
  • Technical Paper
  • 2020-01-0924
To be published on 2020-04-14 by SAE International in United States
Stress and strain measurement of high density polyethylene (HDPE) fuel tanks under dynamic loading is challenging. Motion tracking combined with computer vision was employed to evaluate the strain in an HDPE fuel tank being dynamically loaded with a crash pulse. Traditional testing methods such as strain gages are limited to the small strain elastic region and HDPE testing may exceed the range of the strain gage. In addition, strain gages are limited to a localized area and are not able to measure the deformation and strain across a discontinuity such as a pinch seam. Other methods such as shape tape may not have the response time needed for a dynamic event. Motion tracking data analysis was performed by tracking the motion of specified points on a fuel tank during a dynamic test. An HDPE fuel tank was mounted to a vehicle section and a sled test was performed using a Seattle sled to simulate a high deltaV crash. Multiple target markers were placed on the fuel tank. The motion of these markers was captured using…