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This paper presents a methodology for analyzing the multiaxial loads acting on a steering knuckle under operating conditions. The knuckle is a critical structural part which connects the wheel in a car to the steering and suspension system. Computeraided modeling and analysis were carried out on the knuckle, and the results were compared for conven...
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... suspension of modern vehicles needs to satisfy a number of requirements such as loading, driving condition and type of road surface. The steering knuckle is one of the main components used in the McPherson suspension system (Figure 1) in automobiles subjected to millions of varying stress cycles during their life [5]. This demands the thorough study and understanding of the behavior of the steering knuckle under operating conditions. ...
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... steering knuckle located in a McPherson suspension system was attached to a strut tube at the top and the lower arm was placed at the bottom tie-rod on the side, as shown in Figure 1. The directions of forces acting on it varied with load cases and the vehicle specification. ...
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... contour plot for 15% reinforced TiC MMC before optimization is shown in Figure 10(a). It shows that the knuckle life is a minimum 1.65×10 6 cycles in the steering-arm region and a maximum 1.2×10 7 cycles for other portions of the knuckle. ...
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... shows that the knuckle life is a minimum 1.65×10 6 cycles in the steering-arm region and a maximum 1.2×10 7 cycles for other portions of the knuckle. For the MMC knuckle with 15% TiC, the obtained life of 1.95×10 6 is shown in Figure 10(b). The knuckle can survive a minimum of 110 6 cycles to achieve the required life. ...
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... is possible only when the damage value is not more than one. Figure 11 shows damage value of less than one for 12%TiC and 15% TiC reinforcement knuckles. The other materials, ductile iron, LM 6 matrix alloy and 10% TiC MMC, failed. ...
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... other materials, ductile iron, LM 6 matrix alloy and 10% TiC MMC, failed. The damage comparison presented in Figure 11 suggests that except for the LM6 matrix alloy the damage values for all the materials were less than one after optimization. A damage contour plot for 15% TiC MMC before optimization is shown in Figure 12(a) and indicates that the crack initiation spot was present on the edge and increased the damage. ...
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... damage comparison presented in Figure 11 suggests that except for the LM6 matrix alloy the damage values for all the materials were less than one after optimization. A damage contour plot for 15% TiC MMC before optimization is shown in Figure 12(a) and indicates that the crack initiation spot was present on the edge and increased the damage. This is in agreement with the findings of Triantafyllidis et al. [7]. ...
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Citations
... However, the published results indicate possible failures in some automotive components, especially the mechanical parts. Among the mechanical parts of a car, a lot of attention has been paid to the steering knuckle as one of critical parts of the steering and suspension systems [26][27][28][29]. In this regard, this part is considered as a super critical component because if it fails in any of the connections, it will lead to an accident and injury to the passenger. ...
This article presents the static performance of composite steering knuckle due to drive on an equivalent road, including different types of roughness and maneuvers. To achieve this purpose, the driving of a full-vehicle model was simulated using the multi-body dynamics (MBD) method, and the imposed loads on connection points of the steering knuckle to different components of the suspension system were extracted considering various maneuvers. Next, CATIA software was used to prepare a smooth model of the steering knuckle by employing coordinate measuring machine (CMM) data. Stress analysis was performed under the maximum value of the loading history in finite element (FE) software. Eventually, the safety factor was calculated based on some well-known criteria for static failure of the composite materials. Moreover, the optimum value of tungsten carbide as a reinforcing substance in aluminum composite was estimated to increase failure strength. The results show that an increase in tungsten carbide leads to an increase in the strength of the steering knuckle under purely axial loads (normal stress criterion) and also that an increase in this substance leads to a decrease in the strength of the part under shear loads (shear stress criterion). Therefore, based on the nature of the loads (i.e., multi-axial non-proportional random amplitude loading conditions) applied to the automotive steering knuckle due to actual conditions, this metal matrix composite (aluminum matrix and tungsten carbide as reinforcement) is not practical.
... Additionally, this component has a complex and variable geometry. In other words, its geometry changes depending on the specifications of the steering system and the suspension system, including the spatial coordinates of other parts, assembly constraints, and joints, etc. [11,12]. However, depending on the classification of the car, different materials (cast iron, forged iron, aluminum, and composite materials) are used to make the car steering knuckle [13]. ...
... The results of the stress analysis showed that the critical area detected by the present finite element model is consistent with the fracture zone under the full-scale axial fatigue test with variable amplitude loading ( Figure 9). Moreover, this area has been reported as the prone zone to fatigue failure in the automotive steering knuckle by other scholars [12,28,32,33]. However, some researchers also reported another area as a failure zone [43][44][45]61]. ...
The main aim of the present paper is to assess the fatigue lifetime of ductile cast iron knuckles as one of the critical components of an automotive steering system. To this end, a real driving path, including various maneuvers, such as acceleration, braking, cornering, and moving on various types of road roughness, was considered. Different load histories, which are applied on various joints of the component (i.e., lower control arm, steering linkage, and Macpherson strut), were extracted through Multi-Body Dynamics (MBD) analysis of a full vehicle model. The achievements of previous studies have proved that the steering knuckle fails from the steering linkage and due to the rotational motion. Therefore, only this destructive load history was considered in future analyses of the present study. The CAD model was created using Coordinate Measuring Machine (CMM) data and some corrections in CATIA software. Furthermore, transient dynamic analysis was performed, and the time history of von Misses equivalent stress was obtained at the root of the steering linkage (which is exactly the location of failure based on the laboratory data as well as finite element simulations validated by the author in the previous studies). To predict the fatigue life of a component, two different methodologies were considered. Firstly, some well-known criteria were employed for equalization of load spectrum to a Constant Amplitude Loading (CAL). Then, fatigue analysis under sinusoidal loading was performed. Secondly, the fatigue life of the component considering Variable Amplitude Loading (VAL) was predicted using the Critical Plane Method (CPM), employing the Rain-flow cycle counting technique, and utilizing the Miner–Palmgren damage accumulation rule. Eventually, to evaluate the prediction accuracy of different methodologies, the obtained results were compared with the full-scale axial variable amplitude fatigue test which was performed by the corresponding author. The results indicated that the prediction of variable amplitude fatigue lifetime by Finite Element (FE) analysis in the time domain has about 21% error compared to reality. Additionally, the relative error between the results obtained from two different methodologies is about 20%, which is acceptable due to the scattering of the fatigue phenomenon results, the complex geometry of the part, and the complicated loading.
... Digital image correlation for measuring displacement on solid surfaces was introduced in the 1980s by researchers at the University of South Carolina. In recent years, this technique has been improved and optimized by many researchers [4][5] and has been applied to surface deformation measurement using images from Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), and X-ray microtomography [6]. Quite recently, DIC has been used to experimentally study bonded and experimental analysis of composite bolted joints using digital image correlation bolted joints of composite materials. ...
... The value of 11° of bolt inclination angle is detected, followed by a short load drop at point (4). ...
... It was concluded that bolt inclination angle is influenced by load, laminate pattern plies 0° and micro-buckling of fibers at 45°and -45. Bearing rupture induces the charge to drop slightly at point (field yy (%) of the single-lap composite joint during the experimental tensile test (front side)The value of 11° of bolt inclination angle is detected, followed by a short load drop at point(4). The composite fastened joints can still carry an additional load (point 5) of the load displacement curve with an angle of 21° and followed by plies delamination at 23° value of angle, causing increases again until the ultimate charge is reached at point (6) witch coincide of 13° of bolt angle. ...
... Researches on fatigue degradation have shown links between the different mechanical properties of the material, such as: flow limit, tensile strength, toughness and the fatigue life (e.g. [7]- [10]). Loads have been defined so that they match as much as possible with real conditions. ...
... In other words, it does not have a specific shape and differs from car to car. Moreover, depending on the auto parts manufacturer, the steering knuckle is made of different materials including cast iron, aluminum alloy, and forged steel [1,2]. ...
In this paper, the author has attempted to investigate the effects of different loading conditions including axial and multiaxial variable amplitude loading (VAL) on the fatigue life assessment of automotive components under various maneuvers. To this end, a case study was conducted on the cast iron steering knuckle of a passenger car. In fact, the various VAL histories are entered on the three joints of knuckle, namely steering linkage, lower control arm, and MacPherson strut. However, previous studies have shown that this high super-critical component fails through the steering linkage. Moreover, the rotation of the steering linkage is the most destructive load. Hence, in this research, different loading cases such as axial (destructive load as means 1 channel), multiaxial (only relates to loading on the joint of knuckle and steering linkage means 3 channels), and full multiaxial (including all loading time histories means 9 channels) were considered. Afterward, finite element analysis was performed for each case, and fatigue life of the component was predicted under different conditions. Next, fatigue life of the component was evaluated using the time histories of stress tensor in the root of steering linkage which is extracted by transient dynamic analysis and applying probabilistic approach based on the Liu–Zenner equivalent stress criterion. Eventually, the responses from both techniques were compared in different cases. The results reveal that life predicted using two methods are slightly different. But, the results of probabilistic approach are more accurate than the results of FEM in comparison with experimental data for the axial state. Also, one of the major achievements of this study is that for the components with complex geometry and under multi-input loading like the steering knuckle, it is essential to perform fatigue analysis by considering all real conditions and cannot be only focused to the destructive loading.
... V. Sivananth and S. Vijayarangan has done optimization of passenger car steering knuckle for the fatigue loading and he found that steering arm region is the critical part under the cyclic loading conditions. The failure region of the knuckle was optimized under operating load conditions and fatigue life increased [5]. Ti6Al4V alloy parts are widely used in this sector because of their good mechanical properties-to-weight ratio. ...
Weight optimization plays vital role in performance improvement for an automobile. In vehicle, steering knuckle is one of critical components as it is subjected to millions of varying cyclic loads and it contributes to unsprung mass of vehicle. Therefore, steering knuckle of passenger vehicle is selected for this research work. The aim of this research work is to relate optimized shape of the part with bionic shape, which will give the optimum design. Topology optimization is used as a tool for getting optimum material layout with given space and boundary conditions. The objective function for topology optimization is to maximize stiffness with minimum mass constraints as 30%. The optimization is done by Altair INSPIRE software in which the part is imported as cad model with SG 500/7 as part material. The final surface modeling is done by Polyworks software package for parametric model and result of that modelling has been applied for the standard analysis of the part. The proposed design of the parts meets the strength and stiffness as per requirement. For physical prototype the part is manufactured by additive manufacturing using AlSi10Mg as a material and required properties for same material is also generated. New proposed design of the part shows that there is reduction in weight by 35%.
... The tensile test is a method used to evaluate the structural response of steel to applied force with the result expressed as a relationship between stress and strain. The current study follows several previous researches that had dealt with macroscopic and microscopic behaviour and fatigue properties of pre-hardened austenitic stainless steel [26][27][28][29].Plastic deformation during forming can lead to deformation-induced transformation from the original ductile austenite phase to a stronger martensite [30][31][32][33]. In general, the formation of martensite depends on chemical composition, temperature, stress state, strain and strain rate [34][35][36]. ...
This paper aims to study the properties of 300µm thickness 304 stainless steel. This research topic was selected considering the high demand for the production of small products such as smart phones, solar systems, hard drives, etc. Stainless steel was chosen for its low cost, suitable weight, and good mechanical properties in terms of strength and deformation compared to other materials. However, specimen size and strain may affect the results achieved. In this study, the effects of 2% and 5% strains on the fatigue strength of very thin 304 stainless steel sheets were investigated. Fatigue samples were cut into dumbbell-shapes with a rectangular cross-section as per ASTM E8. The tensile testing results showed that 300µm thickness heat-treated specimen sheets had less strain hardening with clear evidence of yielding. The fatigue test showed that higher strain values lengthened the fatigue life cycles of the stainless steel specimens. From this study, it can be concluded that tensile strain can improve the fatigue strength of very thin 304 stainless steel sheets.
... The Miner's fatigue life summation rule is used to estimate the fatigue life of the wire ropes [18]. Classical fatigue analysis based on the equivalent nominal stress ranges with the Goodman and/or Gerber approach is employed for interpolation or extrapolation of fatigue behaviour with the axial mean stress effect [13,14,[19][20][21][22][23]. This classical method is a phenomenological approach based on the mean load over the net section area of the wire rope. ...
This paper describes a newly-developed damage-based fatigue life model for the long-Term reliability assessment of drawn steel wires and wire ropes. The methodology is based on the computed local stress field in the critical trellis contact zone of a stranded wire rope by FE simulations and the estimated fretting damage of the drawn wire material. A case study using a single strand (1x7) steel wire rope with 5.43 mm-dia. drawn wires is employed to demonstrate the damage-based fatigue life prediction procedures. Under applied tensile loading with peak stress corresponding to 50%MBL (ΔP = 145 kN, R = 0.1), the von Mises stress cycles in-phase and with an identical stress ratio to the applied axial load. The damage initiation life at the trellis contact along the core wire is No = 673 cycles with an additional 589 load cycles to reach the first separation of the material point. The threshold load cycle for the fretting fatigue damage is predicted to be 12.3%MBL. An improved data set of the damage model parameters of the drawn steel wires is indispensable in achieving an accurate and validated life prediction model.
... The brittleness of most composite materials, the possibility of using highly orthotropic laminates to promote high stress concentrations, and the anisotropy in both strength and stiffness properties have to be taken into account when designing composite joints [1]. The joint efficiency and strength when using composites are much lower than those obtained in metallic materials, thereby hindering the widespread application of composites [3][4][5][6]. Digital image correlation for measuring displacement on solid surfaces was introduced in the 1980s by researchers at the University of South Carolina [7]. ...
... The countersunk bolt provides smaller out-of-plane displacement and strain concentrations compared to the socket head bolt resulting in slightly better bearing strength. 6. The use of aluminium single top-hat bushing reduces the bearing strength because it increases the out-of-plane deformation and strain concentrations of the joints. ...
In this work, the application of the digital image correlation (DIC) technique to experimentally study progressive damage of single-lap composite bolted joints is explored. This technique is also used to provide surface strain fields and to analyse out-of-plane phenomena of the joints due to the effect of laminate pattern, laminate thickness, fastener size, fastener type and bushing. The specimens were manufactured from plain weave carbon/epoxy composites. The bearing test was conducted in accordance with ASTM D5961/D5961M-13. The digital image correlation was performed using the commercial Vic-3D digital image correlation system. It was found that strain concentrations observed in the specimens can be used to identify full-field damage onset and to monitor damage progression during loading. Moreover, there is interaction between laminate pattern, laminate thickness, fastener size, fastener type and bushing on bearing strengths (ultimate and 2% offset bearing strengths), surface strain concentrations and out-of-plane displacement. The DIC results can potentially be used to develop and accurately validate numerical models.
... This deterioration phenomenon occurs due to the cyclic stress, known as fatigue and should be detected before it reaches the threshold. The threshold occurs at stresses below the monotonic yield strength and for many years, researchers have conducted various tests to predict the fatigue due to the relationship with the safety of human beings [2][3][4][5][6][7]. Therefore, it is considered as one of the critical area for researchers to study in order to prevent any catastrophic incidents. ...
One of the most important issues yet to be overcome by engineers is the integrity and reliability of engineering structures. This is to ensure the safety of the engineering structure is at the greatest since the catastrophic failures usually occur due to fatigue crack growth. Due to insufficient studies on the fatigue embedded crack growth, the prismatic bar is chosen as the model of the structure. It is wise to select the solid bar since the analysis can be much simpler, thus making it easier to examine the behaviour of the fatigue crack growth. In this study, the metallic square prismatic with embedded cracks is analysed using S-version Finite Element Modelling (S-version FEM) under tension loading. The S-version FEM is an open source program, that is built from codes previously compiled as a program. The S-version FEM structured using the global-local overlay technique consists of two separate global and local meshes. By using the basic concept from the energy release rate and stress intensity factors (SIF), the behaviour of the fatigue crack growth is analysed. From the linear elastic fracture mechanics concept, the SIF is calculated using the virtual crack closure-integral method. The influences of different initial crack size and aspect ratios on the fatigue crack growth are investigated in this study. In addition, the SIF results from the S-version FEM are compared with the analytical solutions. From the analysis, the root mean square errors (RMSE) are performed to support the validation. The RMSE shows a very small error of 0.227, 0.086 and 0.3089 according to the aspect ratio of 0.5, 1.0 and 2.0, respectively. The results also show significant characteristics and behaviour of the SIF trend along the crack front, corresponding to different aspect ratios. From this study, the S-version FEM is suitable to be used to predict the fatigue crack growth for the cracks embedded in a structure. Subsequently, the S-version FEM is an open source program can be modified for increasingly complex engineering problems.
