Automotive Suspension Components Research Articles

Computational evaluation of automotive camber component for light‐weight design

AbstractDue to global warming, environmental issues are one of the most interesting issues in the world. Especially for automobiles that emit pollutants, the issue of lightweight design is one of the important research areas. Thus, this study deals with the lightweight design of a camber link, an automotive suspension component, through finite element analysis. With reference to the camber link made of steel (SM45C) material that has been proven by commercialization, we will replace it with A356 aluminum alloy material to reduce the weight. Here, the design was changed through finite element analysis to reinforce the reduction of rigidity due to material substitution. In particular, we propose a method of designing a camber link considering the safety factor by analyzing the change of stress applied to the suspension. The weight reduction of about 14 % was achieved through static analysis using the weight factor. Using the dynamic optimization method through static analysis using the weight factor and stress ratio, it can be seen that the application is convenient and easy for the lightweight and optimal design of automobile parts.

Comparative study between backstepping and backstepping sliding mode controller for suspension of vehicle with a magneto-rheological damper

The Suspensions are among the important components of vehicles, providing comfort for passengers and protecting the chassis and freight. They are normally provided with dampers that mitigate these harmful and uncomfortable vibrations. This work aims at investigating the potential of the use of the Magnetorheological Damper as a semi-active suspension for passenger vehicles to improve their ride dynamics and to, ensure their manipulability, and reduce unwanted vibrations levels. To achieve desired performances, a hybrid controller based on a backstepping-sliding mode control strategy is derived to increase the dynamic performance of the automotive suspension component and providing comfortable passenger traveling. Numerical simulation is used to test the efficiency of the proposed controller. The obtained results show that the proposed backstepping sliding mode controller is more efficient and robust against road profile excitation and external disturbances in comparison to a classical controller based on backstepping and sliding mode control.

A Method for Comparing the Fatigue Performance of Forged AZ80 Magnesium

A closed die forging process was developed to successfully forge an automotive suspension component from AZ80 Mg at a variety of different forging temperatures (300 °C, 450 °C). The properties of the forged component were compared and contrasted with other research works on forged AZ80 Mg at both an intermediate forging and full-scale component forging level. The monotonic response, as well as the stress and strain-controlled fatigue behaviours, were characterized for the forged materials. Stress, strain and energy-based fatigue data were used as a basis for comparison of the durability performance. The effects of the starting material, forging temperature, forging geometry/configuration were all studied and aided in developing a deeper understanding of the process-structure-properties relationship. In general, there is a larger improvement in the material properties due to forging with cast base material as the microstructural modification which enhances both the strength and ductility is more pronounced. In general, the optimum fatigue properties were achieved by using extruded base-material and forging using a closed-die process at higher strain rates and lower temperatures. The merits and drawbacks of various fatigue damage parameters (FDP’s) were investigated for predicting the fatigue behaviour of die-forged AZ80 Mg components, of those investigated, strain energy density (SED) proved to be the most robust method of comparison.

Automotive suspension component behaviors driven on flat and rough road surfaces

The objective of this study is to identify the behavior of the car suspension components subjected to road surface contours. Strain signals were measured by installing a strain gauge at the critical area of the coil spring and lower arm. The car was driven on a flat and rough road surface with speeds of 30–40 km/h and 10–20 km/h, respectively. According to the fatigue life assessments based on the strain-life approach, it was found that when the car was driven on the rough road, the components received higher stresses, contributing to a shorter fatigue life. The fatigue life of the coil spring when being driven on the rough road was 1,248 cycles to failure, which was more than 14 times shorter when being driven on the flat road, with 19,060 cycles to failure. Meanwhile the fatigue life of the lower arm being driven on the rough surface was 3,580 cycles to failure, which was almost 3,328 times shorter when being driven on the flat road, with 11,914,000 cycles to failure. The useful life of the coil spring was more than 625 times lower than the lower arm when driven on the flat road, whereas when driven on the rough road, the useful life of the coil spring was almost 3 times lower than the lower arm. In conclusion, the coil spring will fail more than 2 times faster than the lower arm. This is because the contour of the road surfaces provide a vertical load, directly working the coil spring which reduces the load vertically, while the lower arm functions to hold the load when turning.

The Hybrid Compression Moulding of Structural Composite Materials for Automotive Applications

The Innovate-UK-funded Composite Lightweight Automotive Suspension System (CLASS) project, led by Ford Motor Company and partnered by Gestamp UK, GRM Consulting and WMG, investigated the use of carbon fibre reinforced composite materials to decrease the weight of a complex automotive rear suspension component in support of reduction in vehicle emissions. A multi-material design comprising discontinuous fibre composite (C-SMC), aligned fibre composite laminate (prepreg) and steel was developed. A high volume hybrid compression moulding manufacturing process was developed at WMG, achieving total press cycle times of around 5 minutes. Prototype parts were manufactured and evaluated using materials characterisation techniques to validate the manufacturing methods. The optimum C-SMC charge pattern was investigated to achieve complete fill with minimal pre-processing. Destructive and nondestructive analysis of the hybrid parts was performed to understand resultant hybrid material macrostructure. This innovative design and manufacturing process resulted in a component 35% lighter than the original multi-piece steel design.

A dual-tree complex wavelet enhanced convolutional LSTM neural network for structural health monitoring of automotive suspension

To increase structural reliability of complex mechanical components under harsh working conditions, a vibration-based structural health monitoring (SHM) method is a promising tool. However, due to non-linear dynamic characteristics and interfering contents in the measured signals, applying a reliable SHM system to practical project is far from an easy work. On the basis of recent studies, an application-oriented SHM method based on a Dual-Tree Complex Wavelet enhanced Convolutional Long Short-Term Memory neural network (DTCWT-CLSTM) has been designed. The method combines three advanced SHM technologies. In its application process, DTCWT is firstly used to obtain multiscale characteristics information of measured signals. A DCNN model is then employed to automatically extract useful damage features. Subsequently, a LSTM model is utilized to predict damage values. The proposed DTCWT-CLSTM is applied to damage prediction of an automotive suspension component under real operation conditions. The experimental results confirm the superiority of our method when compared with several state-of-the-art baseline methods.

Integration of Multi-Gaussian fitting and LSTM neural networks for health monitoring of an automotive suspension component

For mechanical structures under harsh operational conditions, a structural health monitoring method is a promising tool to reduce safety risk and maintenance costs. With the rapid development of advanced sensing and data analysis techniques, a massive research effort has been performed to monitor structural health from vibration signals. However, practical engineering components usually have nonlinear dynamic characteristics and high volume of measured data. Therefore, applying a health monitoring system to an actual project is far from an easy work. Based on the recent field studies, a novel method is proposed to achieve a trade-off between prediction accuracy and computation efficiency. In this method, we integrate a multi-Gaussian fitting feature extraction method and an LSTM-based damage identification method to develop a health monitoring system with available vibration signals. Through the proposed method named GaPSD/LSTM, frequency-domain features from sequential vibration signals are firstly extracted by multi-Gaussian fitting of power spectral density (PSD) curve. Then, a long short-term memory (LSTM) neural network is used to predict partial damage level. The proposed GaPSD/LSTM is validated by automotive suspension durability tests. The experimental results prove that the proposed method can significantly reduce computation time in the condition of achieving great prediction accuracy, compared with several state-of-the-art baseline methods.

Optimization of annealing stack using design of experiment method in Batch Annealed HSLA Steel

Cold rolled HSLA steels are characterized by its high Yield to Tensile strength ratio. These steels are resistant to weld zone softening and grain coarsening, makes it suitable to fabricate to different automotive components. Key application includes automotive structural, reinforcement, suspension and chassis component etc. All these desirable properties are achieved by aiming the desirable chemistry and processing using the desired process parameters. High Strength Low-alloy steel sheets processed through Batch annealed route are prone to mechanical properties variations within batch annealing stack. Mechanical properties are function of actual strip temperature and time. In Batch Annealing, temperature of strip depends upon thickness, width, weight and stack position of the coil. Different coil parameters like weight, width, thickness, outer coil diameter along with process parameters like heating time, stack position were analyzed to work out the source of property variation. By using binary logistic regression it was found that width difference and weight difference are highly correlated with the property variation. Full factorial Design of experiments (DOE) was performed for stack width range and weight range in a stack. DOE response optimizer confirms that keeping width range of coils within the stack to minimum results in property variation of as low as 10MPa.

Effect of Copper on Corrosion of Forged AlSi1MgMn Automotive Suspension Components

Recently, modifications in the alloy composition and the manufacturing process cycle were proposed to achieve a more uniform structure with no evidence of coarse grains across the section of the AlSi1MgMn alloys. Cu was added to the AlSi1MgMn alloy to improve its age hardening capacity without a separate solution heat treatment. However, Cu addition degrades the corrosion resistance of this alloy due to the formation of Al-Cu precipitates along the grain boundaries that are cathodic with respect to the aluminum matrix and thus encourage intergranular corrosion. The present work was undertaken to identify the impact of Cu addition on the corrosion properties of AlSi1MgMn alloys with different Cu contents. A series of AlSi1MgMn alloys with 0.06-0.89 wt.% Cu were tested in order to identify an optimum level of Cu addition.

Ductile Fracture Prediction of Automotive Suspension Components

Ductile Fracture Prediction of Automotive Suspension Components

Evaluation of corrosion fatigue and life prediction of lower arm for automotive suspension component

Lower arm is one of the suspension components of automobile. It is suffered from driving vibration and corrosive environment, namely corrosion fatigue. In this study, corrosion fatigue property of lower arm was investigated, and a modified model based on Palmgren-Miner rule was developed to predict the lifetimes of corrosion fatigue. The corrosion fatigue life of lower arm was about 1/6 times shorter than fatigue life. Based on the results of corrosion fatigue tests and meteorological data in Seoul and Halifax, the corrosion fatigue life of lower arm was predicted. The satisfaction of 10-year and 300,000 km warranty was dominated by the climate of automobile driving. This prediction indicates that the weather condition or driving condition influences the life of automotive parts. Therefore, to determine the warranty of automotive parts, the driving condition has to be carefully considered.

Potential of horizontal direct chill cast EN AW 6082 rods as forging stock in the manufacture of light weight suspension components

Commercial EN AW 6082 rods cast at less than 50 mm in diameter via horizontal casting appear to be adequate candidate as forging stock for the manufacture of small size automotive suspension components. Cast forging stock relies entirely on the forging deformation to develop the fibering known to be very beneficial for superior dynamic and impact properties. Hence, the forging die design is critical to ensure the sufficient amount and suitable orientation of fibering across the section of the component. Forgings produced from cast stock, submitted to an artificial ageing cycle directly after the forging step offer superior fatigue and impact energy values with respect to their counterparts processed with a solution heat treatment (SHT). The superior fatigue and impact energy values of the former are attributed to the particle characteristics; i.e. the spacing of void forming particles in these forgings is relatively smaller than in forgings processed with a separate SHT. The coalescence of voids at these particles eventually occurs at smaller loads and deteriorates toughness.

Reducing cyclic testing time for components of automotive suspension system utilising the wavelet transform and the Fuzzy C-Means

This study aims to introduce a novel method for accelerating fatigue tests. Strain signals measured at automotive suspension components were extracted based on the Morlet wavelet producing damaging segments. Furthermore, the segments were clustered using the Fuzzy C-Means to remove the segments having lower energy. The process was able to shorten the strain signals up to 41.4% and it was able to retain at least 90% of the fatigue damage. It reduced the testing time by more than 33%, with equivalent fatigue life. Indirectly, the use of modified strain signals could reduce device operating costs.

Advanced Properties of Ausferritic Ductile Iron Obtained in As-Cast Conditions

In previous studies, the process parameters to obtain ausferritic ductile iron in as-cast conditions by means of engineered cooling were defined, that is, without an austempering heat treatment. This material was fundamentally characterized, and its mechanical properties were determined. It was demonstrated that obtaining fully ausferritic microstructures by means of engineered cooling was feasible and that the properties met the requirements of the conventionally produced austempered ductile iron. Additionally, an experimental model was developed to define the optimal processing parameters of castings presenting different thermal moduli, in terms of chemical composition, temperatures and time parameters. The aim of the present work is to go into detail about the physical properties of the ausferritic as-cast materials. The chemical composition of the samples was defined by means of the experimental model. The isothermal transformation temperature was changed from 300 to 400 °C, while the other process parameters (shakeout temperature and isothermal transformation time) remained constant. Due to the excellent strength/toughness ratio of these materials, they are prone to being used on different applications such as automotive suspension components, rail components in low temperature environments and pumps and engines exposed to corrosive marine conditions among others. With the aim of responding to this demand, an advanced characterization of the material’s low temperature, corrosion or dynamic properties was performed on this work. These results were compared to the conventionally heat-treated austempered ductile iron as well as other nodular iron ferritic–pearlitic grades found in the literature.

Processing of high strength EN AW 6082 forgings without a solution heat treatment

Light weight EN AW 6082 alloy forgings are used extensively in automotive suspension components. The conventional production cycle involves a solution heat treatment that is responsible not only for coarse surface grains, potentially degrading for fatigue properties, but also for microstructural features that reduce the impact toughness. The separate solution treatment may be omitted if hot forging operation is fine tuned to solutionize sufficient Mg and Si during forging to offer adequate age hardening during the subsequent artificial ageing cycle. Uniform structures with a predominantly fine fibrous core thus obtained, ensure better fatigue and impact properties and a longer service life. The proposed process not only improves the quality of the automotive suspension components but also offers significant cost savings.

A novel processing route for the manufacture of EN AW 6082 forged components

An attractive combination of strength and formability, corrosion resistance and recyclability has made the age-hardening EN AW 6082 one of the most popular aluminium forging alloys. 6082 alloy forgings are thus used extensively in automotive suspension components. The conventional manufacturing cycle starts with the casting of 6082 billets that are subsequently extruded into smaller diameter forging stock. The relatively higher temperatures generated by frictional heating and high strains introduced at the surface during extrusion encourage recrystallisation and produces a heterogeneous structure with fully recrystallised small grains at the surface, fibrous grains at the centre. Hence, the surface of the forged 6082 components inevitably undergoes grain growth once exposed to high temperatures during the solution heat treatment. An attempt was made in the present work to identify an alternative process to achieve a homogeneous section structure with no evidence of coarse grains across the section, which in turn will ensure a better fatigue performance and a longer service life.

EPOSIL® for Automotive Suspension Components, Coils Springs and High Pressure Vessels

EPOSIL® for Automotive Suspension Components, Coils Springs and High Pressure Vessels

The influence of mechanical and CO 2 laser cut-edge characteristics on the fatigue life performance of high strength automotive steels

The cut-edge characteristic properties of automotive structures formed during the mechanical blanking and laser-cutting processes significantly influence fatigue life performance. This factor is becoming increasingly important as S355MC and DP600 high strength steels (HSS) grades under investigation exhibit an increased sensitivity to fatigue cracks initiating from cut-edge regions. It was determined that by manipulating the critical cutting process parameters, clearance in terms of mechanical blanking, and by controlling the interrelationship between power and traverse cutting speed during the laser cutting process can result in optimised fatigue lives being achieved. Optimal fatigue lives were attained by minimising the cut-edge surface damage and by controlling the near edge microstructural deformations during each cutting process. It is the critical significance of fatigue which is the limiting factor towards being able to effectively downgauge steel grades used as automotive chassis and suspension components. This research is some of the first that considers the influence of mechanical and laser cut-edge surface quality and internal properties, which has then been partnered to the critical fatigue performance of HSS grades.

Fracture surfaces and the associated failure mechanisms in ductile iron with different matrices and load bearing

Ductile iron (DI) is a family of cast alloys that covers a wide range of mechanical properties, depending on its matrix microstructure. For instance, ferritic matrices used in parts, such as automotive suspension components, demand high impact properties and ductility among some of their main requirements. On the other hand, pearlitic and martensitic matrices are used when hardness, strength and wear resistance are of particular concern. When it comes to very high strength parts, ausferritic matrices, typically austempered ductile iron (ADI), are widely used. DI has been employed to replace cast and forged steels in a large number of applications and its production has shown a sustained rate of growth over the last decades. Knowing about failure modes and fracture mechanisms associated to materials with the properties mentioned above is crucial, since they can be of great value for designers of mechanical components. This paper deals with the analysis of fracture surfaces of ductile cast iron generated under different conditions of load application, temperature and environments. The studies include the examination of fracture surfaces obtained by means of tensile tests, impact tests and by samples used to determine fracture toughness properties, where the zones of fatigue pre-crack and monotonic load condition were evaluated. A special case of ductile iron fracture is also examined. The study of the different surfaces permitted to establish patterns that contributed to unveil the fracture mechanisms of ductile iron with different matrices, nodule count, etc.

Analysis of manufacturing effects on fatigue failure of an automotive component using finite element methods

ABSTRACTIn this study, the fatigue life of an automotive suspension component was analysed using finite element methods with regard to stamping and welding effects. Because automotive suspension components are produced by forming and welding sheet metal, there are various effects on the final product, such as uneven thickness distribution, residual stresses and weld notches. Manufacturing effects may change the mechanical performance of the automotive components; therefore, it is desirable to consider these effects in the early design stage. Residual stresses due to work hardening and thermal deformation were investigated through process simulation. The redistribution and relaxation of residual stresses in a component were investigated in fatigue life analysis under a cyclic loading condition. Various equivalent relaxation curves were investigated and one was selected after comparisons with test results. The fatigue simulation results were compared to the test results; a good correlation between the two was achieved for the residual stress effects in terms of life cycles and failure locations. The simulation results also show that welding produces more detrimental effects than stamping with regard to the fatigue life of a component.