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Technical Paper

Fatigue Damage of Trim Dies Manufactured or Reconditioned by Different Routes

2022-03-29
2022-01-0245
The compression fatigue behavior of sheet metal trimming die is studied. The trim dies were manufactured or reconditions through different fabrication processes and heat treatment conditions. An accelerated lab testing method is developed to evaluate die damage resistance under compressive cyclic load applied at the tool edge, analogous to sheet metal trimming die operation. The metal removal volume at the sheared edges were measured by image processing to quantify the degree of fatigue damage as a function of loading cycle number. The fatigue microstructural damage were examined with optical and scanning electron microscopies. The simulated die performances are compared among different die processing routes. A phenomenological trim die damage rate model in Paris law form was obtained and tuned with experimental data for tool life prediction.
Technical Paper

Padded Self-Piercing Riveting (P-SPR) on magnesium high pressure die casting

2022-03-29
2022-01-0249
Padded self-piercing riveting (P-SPR) is a newly developed multi-material joining technology to enable less ductile materials to be joined by self-piercing riveting (SPR) without cracking. A deformable and disposable pad was employed to reduce the stress distribution on the bottom surface by supporting the whole bottom sheet continuously during rivet setting process. To verify the P-SPR process, 2.0mm thick 6061-T6 wrought aluminum was joined with 3.2mm thick coated AM60B magnesium high pressure die casting (HPDC) by using 1.0mm thick dual-phase 600 (DP600) steel as the pad. Regular SPR processes with 2 different die geometries were studied as a comparison. Compared to the regular SPR processes, P-SPR demonstrated advantages on coating protection, crack mitigation and joint strength.
Technical Paper

An Investigation of the simulation of sintering distortion in a 316L Part manufactured using Bound Metal Deposition 3D printing

2022-03-29
2022-01-0346
Metal binderjetting is a high throughput additive manufacturing process that has the potential to meet the needs of automotive volume production. In many cases, this process requires a sintering post-process to meet final dimensions. Because the sintering stage is performed free standing (i.e. without the use of tooling) and can involve up to a 20% dimensional change from green part to the final part shape, part distortion can be a concern. In this study, the sintering stage of a bridge geometry was simulated under different parameter settings using a Finite Element Analysis. The sensitivity of the simulation to various process parameter inputs was examined. Parts were then produced in 316L using a bound metal deposition and sintering process and compared to prediction. The sintering simulation indicated good agreement with experiment for some dimensions but highlighted the need for additional analysis.
Technical Paper

Nonlinear Finite Element Calculation of Cold Gas Inflator Housing Ultimate Breakage Load Based on Arc-Length Method

2022-03-29
2022-01-0766
For cold gas Inflator, high refinement of ultimate pressure load forecast of inflator housing is one key of Inflator development. For inflator housing hydro-burst test ultimate load FEA calculation, arc-length method is utilized for obtaining high precision results. At beginning, the material parameters of inflator housing for simulation is correlated. The FEA material model adopts the stress-strain data from uniaxial tensile experiments. Considering the geometrical nonlinearity resulting from large deformation as well as material nonlinearity from plastic hardening, the whole tensile process from tensile deformation to failure of the specimen is stimulated by utilizing the arc-length method. Numerical results show that the arc-length method is appropriate to predict the entire deformation process, and the obtained key deformation stages, the distribution and inclined angle of the localized necking occurs also agrees with that of theoretical analysis.
Technical Paper

Research on electromagnetic shielding technology of special vehicle-mounted shelter based on material-structure co-design

2022-03-29
2022-01-0351
In order to meet the needs of modern warfare, the research on electromagnetic shielding technology of military vehicle-mounted shelters and improving the electromagnetic shielding performance of shelters will play an increasingly important role in the protection of advanced electronic equipment. At the same time, it is also the core of the development of military vehicle-mounted shelters. In this paper, by selecting and comparing different materials, using multi- layer composite materials to design the military vehicle-mounted shelter. The shelter body comprises a front wallboard, a rear wallboard, a left wallboard, a right wallboard, an upper wallboard and a lower wallboard.
Technical Paper

Improving Keyhole Stability During Laser Welding of AA5xxx Alloys

2022-03-29
2022-01-0247
Laser welding of the magnesium-bearing AA5xxx aluminum alloys is often beset by keyhole instability, especially in the lap through joint configuration. This phenomenon is characterized by periodic collapse of the keyhole leaving large voids in the weld zone. In addition, the top surface can exhibit undercut and roughness. In full penetration welds, keyhole instability can also produce a spikey root and severe top surface concavity. These discontinuities could prevent a weld from achieving engineering specification compliance, pose a craftsmanship concern, or reduce the strength and fatigue performance of the weld. In the case of a full penetration weld, the spikey root could compromise part fit-up and corrosion protection, or damage adjacent sheet metal, wiring, interior components, or trim.
Technical Paper

Technical Keynote: Magnesium Sheet Component Development and Demonstration Project

2022-03-29
2022-01-0248
Most of the applications of magnesium in lightweighting of commercial cars and trucks are die castings rather than sheet metal, and automotive applications of magnesium sheet have typically been experimental or low-volume serial production. The overarching objective of project was to develop new low-cost magnesium alloys, and demonstrate warm-stamping of magnesium sheet inner and outer door panels from a 2013 MY Ford Fusion at a fully accounted integrated component cost increase over conventional steel stamped components of no more than $2.50/lb. saved. The project demonstrated the computational design of new Mg alloys from atomistic levels, cast new experimental alloy ingots and explored thermo-mechanical rolling processes to produce thin Mg sheet of desired texture. A new commercial Mg alloy sheet material was sourced and pretreated with protective coil coatings, and its properties fully characterized.
Technical Paper

Investigation on the impact of high-temperature calendar and cyclic ageing on battery overcharge performance

2022-03-29
2022-01-0698
With the degradation of lithium-ion batteries, the battery safety performance changes, which further influences the safe working window. In this paper, pouch ternary lithium-ion battery with a rated capacity of 4.2 Ah is used as the research object to investigate the impact of high-temperature calendar and cyclic aging on the tolerance performance. The overcharge-to-thermal-runaway test is performed on the fresh cell and aged cell (90% SOH). the inflection point of voltage for aged cell appears earlier than that of fresh cell, while the voltage corresponding to the inflection point is the same for them, which means that the voltage at which lithium plating occurs is the same. However, the voltage plateau and the crest voltage before thermal runaway of aged cell is significantly higher than that of fresh cell. Besides, for the thermal runaway triggering, ohmic heat, reversible heat, and side reaction heat all make contribution, among them, the side reaction heat plays a dominant role.
Technical Paper

Thermomechanical behavior of an automotive exhaust aftertreatment application

2022-03-29
2022-01-0277
An aftertreatment system is the back-end component of an automotive exhaust system, used mainly to reduce pollutant emissions. This system is exposed to high thermal loads which can exceed temperatures of 900 oC , usually they operate at temperatures under 600 oC - 700 oC, depending of the engine application. The durability assessment of a system under thermomechanical loads can be challenging due to the complexity of the technical problem, which involves complex material behavior at high temperatures and results in high thermomechanical strains and stresses. This study presents a computational approach for the lifetime assessment of an exhaust aftertreatment system subjected to thermomechanical loading. The method is composed of a fluid flow analysis to compute the temperature fields which are mapped to a mechanical analysis combined with a nonlinear elastoviscoplastic material behavior. Lastly, the lifetime of the overall assembly is assessed through a fatigue analysis.
Technical Paper

Effect of Decoration on Windshield Impact Resistance and Novel Decoration Solution Compatible with Chemical Strengthening

2022-03-29
2022-01-0263
Vehicle windshields typically include a black decorative pattern around their periphery and other regions. Examination of field failed parts has shown that windshields often break from impacts in these decoration zones; often with the fracture initiating from the decoration material itself. In this work, the effect of different glazing decoration materials on glass strength and laminate impact resistance was evaluated. The decoration materials investigated included traditional inorganic enamel frit, an organic ink, and a new enamel frit that is compatible with glass chemical strengthening. Ring-on-Ring strength tests were conducted and showed that inorganic enamel frit reduces strength of glass by over 50% compared to undecorated glass, while organic inks do not adversely affect strength. Tests of a newly developed decoration frit material, compatible for chemical strengthening processes, showed strength levels that were on par with undecorated, unstrengthened glass.
Technical Paper

Sensitivity of Solid Element Spot Weld Modeling Methodology to Nugget Diameter

2022-03-29
2022-01-0777
A vehicle’s structure has more than 4000 spot welds, which can be considered as one of the main design criterion that affects the general stiffness as well as the durability of an automobile. Considering the essential role of finite element based simulations of the spot welded structures on the design phases of vehicle development, accuracy of analyses can be considered as one of the main concerns to meet the design objectives. This study examines the sensitivity of solid element spot weld modeling technology to nugget diameter. Comparative stress and multi-axial low cycle fatigue analyses are conducted for the inspection of the effect of weld diameter on solid element spot weld simulations. Displacement contours as well as local stress profiles at the vicinity of the spot welds are examined to evaluate the effect of nugget diameter on general stiffness and safety.
Technical Paper

Validating the design of CV axle for BAJA SAE ATV

2022-03-29
2022-01-0644
Axle transmits power from the gearbox to the wheels. There are primarily two reasons for reducing the axle’s diameter in the case of a bipod CV joint (Constant-velocity joints axle), to avoid overdesigning and less articulation angle. As the ATV (All-Terrain Vehicle) goes in bumps and droops, a driveshaft with a larger diameter would hit the walls of the CV joint, which will create a hindrance in its articulation. Moreover, if the driveshaft is overdesigned, it will add unnecessary weight and effort to the power train, which would decrease the overall performance of the vehicle. The diameter of the axle was reduced using real-time testing data of peak torque production from the powertrain unit (Engine + CVT (Continuously variable transmission )+ Gearbox) with the help of various machines to validate that component do not fail under the given load conditions; research work is divided into 3 phases of data collection, axle design, and validation.
Technical Paper

Wear and Corrosion Behaviours of PEA Alumina Coatings on Gray Cast Iron

2022-03-29
2022-01-0329
Alumina (Al2O3) thin film coatings are applied on Al alloys using Plasma Electrolytic Oxidation (PEO) method to reduce the wear and corrosion problems. Plasma Electrolytic Aluminating (PEA) is a technique that could generate Alumina coatings on cast iron, mild steel, and copper alloys. In this study, the aim is to explore the anti-wear and anti-corrosion behaviours of PEA Alumina coatings on gray cast iron. The dry sliding tribology test data was obtained from Pin-on-Disk (POD) tests against SAE 52100 steel and Tungsten Carbide (WC) counterfaces. Comparing to the PEO Alumina coatings, the PEA Alumina coating has a much lower Coefficient of Friction (COF) and less wear. The microstructure, chemical composition, and phase composition of this coating were investigated with Scanning Electron Microscope (SEM), Energy-Dispersive X-Ray Spectroscopy (EDX), and X-Ray Diffraction (XRD), respectively. There was FeO (or FeAl2O4) found on the PEA Alumina coating.
Technical Paper

Novel Nanocrystalline Silver Alloy Coatings to Boost Performance of EV High Voltage Interconnects and Charging Interfaces

2022-03-29
2022-01-0723
Electric vehicle performance needs challenge connector designers and powertrain engineers with new paradigms for performance under more rigorous operational conditions. Traditional connector design protocols direct the engineer to silver plating for the contact interface, but these coatings have a maximum interface temperature of 170 C (ambient temperature plus T-rise). To avoid thermal runaway, engineers have to derate the ampacity of powertrain connections, which reduces available energy delivery as the temperature increases. This is especially true during transient power events like regenerative braking and acceleration. The soft nature of silver coatings make them well suited for power delivery and low contact resistance, but requires an engineering trade-off for wear durability. This is especially problematic for charging connectors which require tens of thousands of mating cycles before failure.
Technical Paper

Adjoint method for the optimisation of conformal cooling channels of 3-D printed high-pressure tools for aluminium casting

2022-03-29
2022-01-0246
The emergence of additive manufacturing (AM) technology has enabled the internal cooling channel layout for high pressure aluminium die casting (HPADC) tools to be designed and modified without topological constraint. Optimisation studies of a full industrial HPADC mould for extending the tool service life has received limited attention due to the high geometrical complexity and the various physics with multi time and length scales in addition to the manufacturability limitations. In this work a new computational efficient algorithm that employs the adjoint optimization method has been developed to optimize the coolant channels layout in a complete mould with various 3D printed inserts. The algorithms reduced significantly the computational time and resources by decoupling the fluid flow in the coolant channels from the tool and simulating them separately.
Technical Paper

Forming Characteristics of Very Low Carbon High strength Dual Phase Steels Produced through a Flex Mill Continuous Galvanizing Line

2022-03-29
2022-01-0239
A very low carbon (<0.06 wt%), lean alloyed chemistry approach is utilized for the development of high strength dual phase (DP) steels with enhanced global and local formability though EAF-LMF-CSP route. Optimized process conditions including clean steel practices, choice of suitable casting powder, hot rolling and continuous anneal set points resulted in excellent mechanical properties and formability characteristics of the subject DP steel. The enhanced balance of strength and formability (hole expansion ratio values of 26- 35% for thicknesses of 0.80-1.40mm) is attributed to the optimization of the microstructure through refinement, homogeneity, isotropy and balancing of microconstituent mechanical response. In this contribution, production strategy and formability characterization of DP steels with tensile strengths of 780 MPa and above relevant to automotive body structure applications are discussed.
Technical Paper

Evolution and Redistribution of Residual Stress in Welded Plates During Fatigue Loading

2022-03-29
2022-01-0257
The presence of residual stresses affect the fatigue response of welded components. In the present study of a thick welded cantilever specimen, residual stresses were measured in an as-welded A36 steel sample and in a sample subjected to a short history of bending loads where substantial local plasticity is expected at the fatigue hot-spot weld toe. Extensive XRD measurements describe the residual stress state in a large region in front of the weld toe both in an untested as-welded sample and in a sample subjected to a short load history that generated an estimated 0.01 strain amplitude at the stress concentration zone at the weld toe. The results show that such a test will significantly alter the welding induced residual stresses. Fatigue life prediction methods need to be aware that such alterations are possible and incorporate the effects of such cyclic stress relaxation in life computations.
Technical Paper

Local Thermomechanical Processing for Improving Formability of High Strength Aluminum Sheets

2022-03-29
2022-01-0244
Limited room temperature formability hinders the wide-spread use of high strength aluminum alloys in body parts. Forming at warm temperatures or from softer tempers are the current solutions. In this work, our approach is to start with age-hardened sheets from 7xxx and 6xxx family of alloys and improve their formability using local thermomechanical processing only in the regions demanding highest ductility in the forming processes. We achieved local formability improvements with friction stir processing and introduce another process named roller bending-unbending as a concept and showed its feasibility through finite element simulations. Initial results from FSP indicated significant deformation in the processed zones with minimal sheet distortion. FSP also resulted in dynamically recrystallized, fine grained (d <5 µm) microstructures in the processed regions with textures significantly different from the base material.
Technical Paper

Development of FE modeling Procedures for Laser Welded Aluminum Structures in An Electric Vehicle Battery Module and Validation by Test Data

2022-03-29
2022-01-0317
High strength and thin materials are widely adopted in modern electric vehicles for lightweight design to achieve high energy efficiency. For battery modules, 5000 and 6000 aluminum are typically utilized as a structural material with a thickness range between 1 to 5 mm. Laser welding is one of the most optimum welding tools for joining such a thin material due to its unique advantages, e.g., high welding speed, high accuracy, high energy yet the smallest possible heat affect zone, etc. This paper aims to develop a simplified yet effective FE modeling procedure to simulate the laser welding effects on the aluminum structures used in electric vehicle battery modules. A sequentially-coupled thermo-mechanical analysis procedure is developed to determine the softened zone size for aluminum weldments. Then a tie-rupture weld model incorporates the softened zone to predict the weld failure strength.
Technical Paper

Computer Aided Engineering-based Evaluation of a Purpose-built Tooling Concept for the Electroplating of Functional Coatings on Aerospace Components

2022-03-08
2022-01-0045
Industrial hard chrome plating is a rather complex, lengthy and labour-intensive process: typically, the low cathodic current efficiency of Cr plating baths results in limited deposition rates, taking an hour to deposit a thickness of 25 mm on any size of the part. In the majority of cases, the hard Cr plating process requires the use of tooling structures, making the process strongly operator-dependent and therefore, highly prone to errors. According to the Fokker Landing Gear BV team, operator-independence as well as process simplification are expected to be achieved by developing a purpose-built tooling concept. An intelligent support of employees in their increasingly complex work is also sought and thus far addressed by implementation of modern smart technologies. One of them is computer modeling and simulation, which enables to mirror the physical world in a virtual model.
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