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2017-03-28
Technical Paper
2017-01-0331
Qiuren Chen, Haiding Guo, Katherine Avery, Xuming Su, HongTae Kang
Fatigue crack growth tests have been carried out to investigate the mixed mode fatigue crack propagation behavior of an automotive structural adhesive BM4601. The tests were conducted a compound CMM (Compact Mixed Mode) specimen under load control with 0.1 R ratio and 3Hz frequency. A long distance moving microscope was employed during testing to monitor and record the real time length of the fatigue crack in the adhesive layer. The strain energy release rates of the crack under different loading angles, crack lengths and loads were calculated by finite element method. The pure mode I and mode II tests show that an equal value of mode I strain energy release rate results in over ten times higher FCGR (Fatigue Crack Growth Rate) than the mode II stain energy release rate does. The mixed mode tests results show that under a certain loading angle, the mixed mode FCGR is changed by changing the load, which is contrary to the find in pure mode I and mode II tests.
2017-03-28
Technical Paper
2017-01-0371
Raju Gandikota, Amit Nair, Kurt Miller
Testing elastomeric materials that undergo large strains pose challenges especially when establishing failure criteria. The failure criterion for composites and polymers based on finite elasticity published byFeng (1) requires testing under uni-axial and bi-axial stretching modes. The classic inflation of a circular disk for bi-axial stretch mode poses stability and safety challenges. The test can also be sensitive to end constraints resulting in failure of materials at the constraints. Bi-axial stretching with a hemispherical punch is explored in this work. The bi-axial stretching allows controlled and repeatabletesting. It establishes clear and reliable failure mechanism of the material at the poles. Through a combination of testing and numerical methods, the stretch ratios and its relation to failure has been established.
2017-03-28
Technical Paper
2017-01-0480
Mingde Ding
For structural application, composite parts structure is much more affected by load cases than steel part structure. Engine room bracket of EV, which is structural part and is used to bear Motor Controller, Charger and so on, has different load cases for different EV. Three commonest load cases that are Case 1: bearing 65kg (without suspension part), Case 2: bearing 68kg(including 3.5kg suspension part) and Case 3: bearing 70.1kg (including 5.6kg suspension part). According to topology optimization, structurel 1 was obtained, and then CAE analysis including (strength, stiffness and model) was carried out for abovement three load cases. For Case 1 and Case 2, the analysis result can meet the requirement. However, for Case 3, the stiffness and model analysis result can not satisfy the requirement. To meet the analysis result of Case 3, Structure 1 was optimized and structure 2 was obtained. The CAE analysis was conducted and the results can satisfy the requirements.
2017-03-28
Technical Paper
2017-01-0499
Mingde Ding
Recently, for automotive industry, weight reduction is increasingly needed to improve fuel efficiency and to meet emission requirement. Substituting heavy metallic materials with strong and light composites seems to be the most viable choice to achieve vehicle weight reduction. Because of a high level of styling flexibility and simple process, injection molding is the concern of OEMS. However, injection molding part especially for large part would have large deformation. Therefore, the deformation must be controlled within the requirement during development. According with topology optimization result, we get the structure of IP carrier. The result of moldflow analysis showed that the largest deformation in X direction is 19.4mm, in Y direction is 9.5mm, in Z direction is 13.7mm, which were not satisfy the deformation requirement that was the deformation of the core area must be less than 3mm. By structure optimization, the deformation reduction was obviously.
2017-03-28
Technical Paper
2017-01-1704
D.J. Branagan, A.E. Frerichs, B.E. Meacham, S. Cheng, A.V. Sergueeva
Demand is growing for advanced high strength steels (AHSS) in the automotive industry driven by a desire for lightweighting solutions to meet increasingly stringent fuel economy standards. Formability is a critical factor for producing reduced gauge steel parts with the complex geometries required to maintain stiffness. Global formability represents the ability of a sheet material to be deformed under various stress conditions and to be formed into a part without failure. It can be estimated using forming-limit diagrams or ductility measurements from conventional uniaxial tensile tests. However, these tests cannot reliably assess the local formability at the edges or at the internal holes of the blanks during stamping. Numerous correlations have been previously developed to predict local formability such as yield strength to tensile ratio, true strain at fracture, and post uniform elongation but they are often inaccurate – particularly for AHSS grades.
2017-03-28
Technical Paper
2017-01-1707
C. Matthew Enloe, Jason Coryell, Jeff Wang
Retained austenite stability to both mechanically induced transformation and athermal transformation is of great importance to the fabrication and in-vehicle performance of automotive advanced high strength steels. Selected cold-rolled advanced high strength steels containing retained austenite with minimum tensile strengths of 980 MPa and 1180 MPa were pre-strained to pre-determined levels under uniaxial tension in the rolling direction and subsequently cooled to temperatures as low as 77 K. Room temperature uniaxial tensile results of pre-strained and cooled steels indicate that retained austenite is stable to athermal transformation to martensite at all tested temperatures and pre-strain levels. To evaluate the combined effects of temperature and pre-strain on impact behavior, stacked Charpy impact testing was conducted on the same steels following similar pre-straining in uniaxial tension.
2017-03-28
Technical Paper
2017-01-1269
Xian Wu, Shuxian Zhang
Studies have shown that under in-plane impact loading, negative Poisson's ratio of honeycomb sandwich structure has a good energy absorption compared with the conventional cellular sandwich structure. So, it can be used to protect the key components and the crew from being hurt in the crash accidents. In the design of collision avoidance, both of the energy absorption and the deformation should be considered. In this paper, we designed a honeycomb structure with density gradient which had a good behavior in crashworthiness. Based on the honeycomb sandwich structure with negative Poisson's ratio, we changed the density gradient of the core and studied the energy absorption and the deformation of the structure under impact loading. First, we divided the core into three layers which had different densities. And each layer had the same thickness and the same kind of material. Then, we gave the different permutation and combination of the three layers.
2017-03-28
Technical Paper
2017-01-1266
Qiang Gao, Wang Zhongxing
In order to study the crashworthiness of the concave hexagonal structure with the negative Poisson’s ration under three-point bending, this paper focused on the effect of cellular structure parameters (thickness, width, height, inner concave angle) on the performance using explicit dynamic finite element ANSYS / LS-DYNA. Specific energy absorption (SEA) and peak crushing force (PCF) were adopted as crashworthiness indices. The results showed that: the SEA and PCF increased at the same time with the increase of the thickness of the cell and decrease of the cell height; With the increase of the cell width, SEA increased first and then decreased, while PCF had the opposite trend. SEA decreased with the increase of inner concave angle. When the inner concave angle is small or equal about 45°, PCF was higher. It is benefit to improve the bending performance of the structure by choosing appropriate cellular parameters.
2017-03-28
Technical Paper
2017-01-1666
David Weiss, Orlando Rios
Aluminum alloys containing cerium have excellent castability and retain a substantial fraction of their room temperature strength at temperatures of 200°C and above. High temperature strength is maintained through a thermodynamically trapped, high surface energy intermetallic. Dynamic load partitioning between the aluminum and the intermetallic increases mechanical response. Complex castings have been produced in both permanent mold and sand castings. This versatile alloy system, using an abundant and inexpensive co-product of rare earth mining, is suitable for parts that need to maintain good properties when exposed to temperatures between 200 and 400°C.
2017-03-28
Technical Paper
2017-01-0508
Gabor Kiss, Yuya Ando, Martin Schifko
After the e-coating the paint on the surface is like a sponge and carry liquid which slowly drains off. The retain water carries about 5-10 liter for 100mm² BIW surface area. When the retain water drains off, residual liquids may areas at areas nobody is expecting. These liquids are potential causers in the oven either to destroy the corrosion protection mainly caused by boiling or may lead to bake drips. The density of the residual liquid is changing during the heating process in the oven. Depending on the evaporation of residual puddles and density change the total volume may increase although the weight is getting less. This is the critical situation which may lead to bake drips. In this talk we would outline our technology which allows to predict retain water behavior and the arising of bake drips successfully
2017-03-28
Technical Paper
2017-01-1264
Edward John Vinarcik
6061-O temper extruded rod may be used as feed stock in forming processes for automotive pressure vessel applications. Key parameters for forming are the strength and hardness of the material. The purpose of this paper was to reduce variation in hardness to achieve a process capability index of 1.33 or greater. Among the process steps affecting hardness, annealing is the most critical. Initially, the process showed unacceptable hardness variation. Initial anneal recipes called for a 4-hour soak at 775°F. Initial process capability for hardness was a Cpk of 1.12, with tensile strength readings very close to the upper specification limit. Initial temperature uniformity surveys of the anneal oven showed a large variation in temperature distribution, with some areas of the oven staying below 650°F. Initial improvement efforts focused on soak time. While this did greatly improve the material, the improvement did not have enough of an effect on hardness to achieve a good capability.
2017-03-28
Technical Paper
2017-01-1265
Nia R. Harrison, S. George Luckey, Breana Cappuccilli, Ghassan Kridli
The typical paint bake cycle includes multiple ramps and dwells of temperature through e-coat, paint, and clear coat with exposure equivalent to approximately 190°C for up to 60 minutes. 7xxx-series aluminum alloys are heat treatable, additional thermal exposure such as a paint bake cycle could alter the material properties. Therefore, this study investigates the response of three 7xxx-series aluminum alloys with respect to conductivity, hardness, and yield strength when exposed to three oven curing cycles of a typical automotive paint operation. The results have indicated that alloy composition and artificial aging practice influence the material response to the various paint bake cycles.
2017-03-28
Technical Paper
2017-01-1271
David Wright, John Henshaw, Nia R. Harrison, S. George Luckey
High-strength aluminum alloys such as 7075 can be formed using advanced manufacturing methods such as hot stamping. Hot stamping utilizes an elevated temperature blank and the high pressure stamping contact of the forming die to simultaneously quench and form the sheet. However, changes in the thermal history induced by hot stamping may increase this alloy’s stress corrosion cracking (SCC) susceptibility; a common corrosion concern of 7000 series alloys. This work applied the breaking load method for SCC evaluation of hot stamped AA7075-T6 B-pillar panels that had been artificially aged by two different artificial aging practices (one-step and two-step). The breaking load strength of the specimens provided quantitative data that was used to compare the effects of tensile load, duration, alloy, and heat treatment on SCC behavior.
2017-03-28
Technical Paper
2017-01-1270
Xiaoming Chen
As future vehicles need to improve fuel economy, the use of magnesium for lightweight component is increasing to enable fuel consumption reductions. The finite element modeling of magnesium, especially at limit states can be improved by incorporating shear behavior. Three shear strain coupon test samples were developed for magnesium alloys. The samples generated shear failures in the specimens while using a uniaxial servo-hydraulic load frame. Three dimensional digital image correlation was used to optically measure the full-field strain on the surface of the test specimens. Finite element simulations were conducted on selected shear samples for steel and aluminum using magnesium material input to locate shear zones. Initiators were created to force material damage to initiate in the shear zones. The samples were tested using cast magnesium AM60 and extruded magnesium EZ20. The results showed that damage and material separation in all samples started at the initiators.
2017-03-28
Technical Paper
2017-01-1268
Xiaoming Chen
In recent years, lightweight structure designs become one of the major trends in automotive industry. There are four major aspects that are considered to develop lightweight automotive structures, including using advanced materials, manufacturing methods, design optimization, and additional cost of weight saved assessment. This paper presents the development work of a lightweight subframe for a compact car using Magnesium Casting design. The subframe design needs to meet NVH, strength, and durability, corrosion, and joint strength as well. CAE tools are heavily used to generate and validate the structural performance of the design, including topology and shape optimization, static stiffness, modal, strength and durability analyses. A prototype is also built for component and field tests to validate the feasibility of this design, including component modal test, strength test, and durability test, and vehicle proving ground durability test.
2017-03-28
Technical Paper
2017-01-0357
Dattaprasad Lomate, Asim Tewari, Prashant Date, Manoj R Ukhande, Girish M Shegavi, Raj Kumar Prasad Singh
The application of induction hardening treatment plays a vital role for enhancing fatigue life of various automotive components. This will incorporate compressive residual stresses in the component at significant extent. In this paper, wide range of experiments have been carried out on Rotating Bending Fatigue (RBF) specimens made from 38MnVS6 micro alloyed steel with induction hardening up to three different case depths. The set of specimens are fatigue tested at fully reverse loading condition using rotating bending fatigue testing machine. Based on this study a surface treatment factor is evaluated. This surface treatment factor is used as an input for evaluating precise fatigue life of the specimen using FEA packages. The fatigue life evaluated using FEA is showing good agreement with the results obtained through tests on the actual specimens.
2017-03-28
Technical Paper
2017-01-1664
Yong Tak Kim, Yeongpyo Kim, Namyeul Ryu
Vehicle brake friction output is influenced by the performance of many brake corner system components. For the highest and most table friction output, each component needs to work properly. For each component of the brake corner system, there are many factors related to the final corner friction value. This paper focuses on the relationship between the chemical composition of a cast iron brake rotor chemical contents and the friction output value. Alloying elements have complex interaction effects. In this paper, a numerical analysis tool is applied to dyno bench test results to forecast braking friction values for specific cast rotor chemical compositions. To see why some rotors can achieve high friction values, the rotor microstructure is analyzed. An optimal rotor casting chemical composition recipe, based on set formula and DFSS method, is recommended.
2017-03-28
Technical Paper
2017-01-0336
Edward Punch, Frederick Brust
Weld simulation provides an opportunity to anticipate problems of welding distortion, which affect fabrication cost, and residual stresses which affect fatigue life. A key part of advanced manufacturing, it is used extensively in the heavy equipment and nuclear industries. Although it is possible to perform weld simulation by transient thermal finite element analysis, the concentrated nature of weld heat makes it tedious and time-consuming to mesh the welds adequately. Instead, singular asymptotic temperature distribution functions can be used to model heating and cooling within a concise iterative technique. Weld passes are specified in the final structural mesh by a convenient Graphical User Interface (GUI), while an efficient Virtual Element Detection (VED) scheme keeps track of which weld pass elements are structurally active at a particular time.
2017-03-28
Technical Paper
2017-01-0500
Yuksel Gur, David Wagner
With the continuing challenges of future fuel economy targets carbon fiber composite materials are one facet of a lightweighting strategy to enable reduced fuel consumption. In general, use of lightweight materials such as carbon fiber composites in vehicle design generates vehicle NVH performance degradation. To address this potential issue at the design phase, there is a need to develop correlated CAE models for carbon fiber vehicle parts to evaluate the NVH impact of carbon fiber material use in vehicle design. To develop correlated CAE models for lightweight vehicle design with the use of carbon fiber composite vehicle body parts, an experimental study was conducted to determine the material and NVH characteristics of the carbon fiber composite materials. In this paper, the damping properties and NVH modal analysis results for structural carbon fiber thermoset composite plaques and body parts (oil pan, B-pillar upper insert and B-pillar lower insert) are presented.
2017-03-28
Technical Paper
2017-01-0486
Daniel Frantz
In light of growing global awareness of environmental concerns, automotive manufacturers have received pressure from governmental regulations and consumer demand to incorporate more recycled materials into vehicle production. Polyamide 6 (nylon 6, PA6), a polymer used in many automotive components, is a prime target for the incorporation of recycled materials. PA6 is used and recovered by the carpet industry, and can be processed into a usable recycled polymer (RPA6). To evaluate the potential use of RPA6, injection molded samples comprised of RPA6, glass fiber, and one of three recycled fillers (rice husk ash, micronized rubber powder, and torrefied biomass) will be prepared and subjected to mechanical, thermal, morphological, and rheological testing. It is predicted that these materials will meet the requirements for automotive door handles, engine fan shrouds, and turn signal arms, which are typically made from glass-reinforced nylons.
2017-03-28
Technical Paper
2017-01-0505
Aditi Chavannavar
Polyurethane dispersions (PUDs) have seen rapid growth in recent years as alternatives to their solvent based analogs. They offer the advantages of enabling low VOC formulations while providing superior appearance and mechanical properties. Polyurethane-acrylic hybrids combine the advantages of a polyurethane dispersion with the benefits of an acrylic emulsion. This synergistic combination offers properties such as good hardness development and chemical resistance in addition to enhanced mechanical properties. In this paper, we discuss new PUD-acrylic hybrids that are NMP and solvent free, have a pendulum hardness of 100 oscillations compared to a standard acrylic emulsion that has 80; and offer excellent scratch and abrasion resistance equivalent to that of an acrylic system. In addition to these, the new polyurethane dispersions provide good haptic qualities and have excellent adhesion to plastic substrates such as ABS, PC, PMMA and PVC.
2017-03-28
Technical Paper
2017-01-1708
Saeid Nasheralahkami, Collin Malek, Erika Rugh, Weitian Zhou, Daniel Kowalsky, Sergey Golovashchenko
In recent years, dual phase (DP) Advanced High Strength Steels (AHSS) and Ultra High Strength Steels (UHSS) are considered as prominent materials in the automotive industry due to superior structural performance and vehicle weight reduction capabilities. However, these materials are often sensitive to trimmed edge cracking if stretching along sheared edge occurs in such processes as stretch flanging. Another major issue in the trimming of UHSS is tool wear because of higher contact pressures at the interface between cutting tools and sheet metal blank caused by UHSS’s higher flow stresses and the presence of a hard martensitic in the microstructure. The objective of the current paper is to study the influence of trimming conditions and tool wear on the quality of trimmed edge of DP980 steel sheet. For this purpose, mechanically trimmed edges were characterized for DP980 steel and compared with other steels such as HSLA350 and BH210.
2017-03-28
Technical Paper
2017-01-0339
Sandip Datta, Neil Bishop, Karl Sweitzer, Alexander Atkins
For many automotive systems it is required to calculate both the durability of the part and to rule out the possibility of collision of individual components during severe base shake vibration conditions. Advanced frequency domain methods now exist to enable the durability assessment to be undertaken fully in the frequency domain and utilizing the most advanced and efficient analysis tools. In recent years new capabilities have been developed which allow hyper sized models to be processed onto which multiple correlated loading is applied. The most advanced stress processing (eg, complex von-Mises) and fatigue algorithms (eg, Strain-Life) are now included. Furthermore, the previously required assumptions that the loading be stationary, Gaussian and random have been somewhat relaxed. For example, mixed loading like sine on random can now be applied.
2017-03-28
Technical Paper
2017-01-0502
Mingde Ding
The IP carrier plays a very important structural and safety role in the vehicle. Functionally, it forms the skeleton of the cockpit, providing the base architecture off which IP components are attached and function. At present, the IP carrier is commenly used steel, and is welded by more than 20 parts. Its weight is usually 8-14kg. For the reason of fuel efficiency and enviromental friendly, lightweight of the IP carrier is very necessary. Various lightweight technologies have been applied to IP carrier: Magnesium alloy part, Alluminum alloy part, Hybrid composite part, Composite material injection part. For Magnesium alloy part, the IP carrier which have the equal performance compared to steel part can be integrated to one part, therefore the production process is simplified. Weight can be reduced 40%-60% However, the magnesium injection part have high process requirement and need postreatment which will add cost obviously. These disadvantages limited the mass production.
2017-03-28
Technical Paper
2017-01-0461
R. Rajendran, Ravikumar N, S.S.M Abdul Majeed
Brake disc provides friction force with minimum weight loss on application of brake. The pad material only experiences more wear and friction. Disc and pad materials are selected to give a stable and high coefficient of friction (0.25-0.40). COF is directly proportional to braking force generated and inversely proportional to the stopping distance. Brake pad is mainly produced from asbestos materials. Asbestos is an excellent material for brake pad application.. Considering the environmental pollution and human health safety, the asbestos cannot be used and there is a need to find an alternate material. The aim of the study is to identify a new material for replacement of pad material in practice. In this study, wear, hardness and friction properties of E glass fibre with epoxy resin and cashew friction dust composite are studied and compared with brake pad material in practice.
2017-03-28
Technical Paper
2017-01-0355
Edinilson Alves Costa, Neil Bishop, Valdir Cardoso
In most aspects of mechanical design related to a motor vehicle there are two ways to treat dynamic fatigue problems, that is: time domain vs. frequency domain approach. Time domain approaches are the most common and most widely used especially in the automotive industries and accordingly it is the method of choice for the fatigue calculation of welded structures. In previous paper frequency approach has been successful applied showing a good correlation with the life and damage estimated by the time one; in this paper the same comparative process has been applied but now extended specifically to welded structures. Both frequency domain approach and time domain approach are used for numerically predicting the fatigue life of the seam welds of a thin sheet powertrain installation bracketry of a commercial truck submitted to variable amplitude loading. Predictions results are then compared with bench tests results, and their accuracy are rated.
2017-03-28
Technical Paper
2017-01-0345
SungChul Cha, Seung-Hyun Hong, Shahriar Sharifimehr
Fatigue behavior of two types of automotive steel, quenched and tempered SUJ2 and carburized SCM820PRH, which are applied as powertrain parts are studied. These two types of steel are different in their hardness distribution from surface to core. The hardness of quenched and tempered SUJ2 is homogeneous, in contrast to that of carburized SCM820PRH (SCM) which decreases from surface to core. These steels are investigated in terms of their monotonic tensile properties and fatigue behavior. A number of predictive methods were used to describe the fatigue behavior of these steels. A simple predictive method is based on approximation of S-N curve from ultimate tensile strength. The well known Murakami’s defect area method was also applied for the prediction of the high cycle fatigue strength.
2017-03-28
Technical Paper
2017-01-0348
Mani Shankar, I V N Sri Harsha, K V Sunil, Ramsai Ramachandran
In an automobile, road loads due to tire-road interaction are transferred to vehicle body through suspension. This makes suspension a critical component from the body durability perspective. During vehicle design and development, optimization of suspension parameters to suit ride and handling performance is a continuous and iterative process. These changes on suspension can affect vehicle body durability performance. This paper tries to establish a process to evaluate the effect of changes in suspension parameters on body durability, thus helping in understanding the impact of these changes. The process starts with virtual model building in Multi Body Dynamics software. The base line model is co-related with testing using responses like spring displacement at suspension, acceleration and strain data at the vehicle body.
2017-03-28
Technical Paper
2017-01-0482
Cristiano Grings Herbert, 1Lt Luiz Rogério De Andrade Lima PhD, 1Lt Cristiane gonçalves PhD
Phthalates have been extensively used in rubbers formulation as plasticizer additive for PVC and NBR promoting processing parameters or reducing cost. The most commonly used plasticizer in PVC compounds was di-2-ethylhexyl phthalate (DEHP) currently not recommend due toxicity. In many studies it is described that DEHP is liable of producing toxic and adverse effects and able to act as potential carcinogenic agent. Therefore it is listed as prohibited to the Global Automotive Declarable Substance List (GADSL). Phthalates alternatives are already available but the compatibility in automotive fuel system with biodiesel was not extensively understood. This aspect is important since plasticizer may migrate and change rubber properties. Tri-2-ethylhexyl trimellitate (TOTM) and di-2-ethylhexyl terephthalate (DEHT) plasticizers have been studied the carcinogenicity and chronic toxicity potential and the migration to blood in medical devices.
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