Finite element analysis and optimization of a mono parabolic leaf spring using CAE software

Suspension is considered as a link between the wheels and the body. It absorbs fatigue loading and energy. Leaf spring is one of the oldest suspension types. Nowadays, parabolic leaf spring is mainly used in heavy load vehicles and machines. Design fundamentals of parabolic leaf spring are based on the strength and comfort. The strength properties of leaf spring are usually determined based on the suspension type and loading. The advantage of the parabolic leaf spring is due to its simple construction, low cost, and easy maintenance. The design also helps in providing the axle support. This paper mainly deals with the suspension uses of parabolic leaf spring. The difference between the normal leaf spring and the parabolic leaf spring is the total number of leaves. A parabolic leaf does not need of more number of leafs because the stress is distribution to the leaf are equally due to its parabolic shape.

Tapered cantilever beams, traditionally termed as leaf springs, undergo much larger deflections in comparison to a beam of constant cross-section that takes their study in the domain of geometric nonlinearity. This paper studies response of a leaf spring of parabolic shape, assumed to be made of highly elastic steel. Numerical simulation was carried out using both the small and large deflection theories to calculate the stress and the deflection of the same beam. Non-linear analysis is found to have significant effect on the beam's response under a tip load. It is seen that the actual bending stress at the fixed end, calculated by nonlinear theory, is 2.30-3.39% less in comparison to a traditional leaf spring having the same volume of material. Interestingly, the maximum stress occurs at a region far away from the fixed end of the designed parabolic leaf spring. Keywords: Parabolic leaf spring, End-shortening, Geometric nonlinearity, Equilibrium Configuration Path, Varying Cross-section.doi:10.3329/jme.v37i0.819Journal of Mechanical Engineering Vol.37 June 2007, pp.47-51

Fatigue life prediction of parabolic leaf spring under various road conditions

The present work investigates the fatigue performance of fibre-reinforced injection-moulded leaf springs. Twenty per cent discontinuous long, short glass fibre-reinforced polypropylene (SFPP) and unreinforced polypropylene (UFPP) materials are used for manufacturing constant-thickness, varying-width, mono leaf spring. Fatigue tests are performed on moulded leaf springs at various alternating loads under the pulsating compression mode at 0.5Hz frequency with the aid of in-house developed fixtures integrated with the servo-hydraulic fatigue machine. During fatigue testing, cyclic load—deflection of the test leaf spring of each and every cycle is measured; the energy dissipation ratio and spring rate of the test leaf springs are reported as an index for the accumulated damage at various stages of its life. Test leaf springs are subjected to fatigue load up to 2×105 cycles or failure, whichever is earlier. SFPP and UFPP leaf springs exhibited drops in the spring rate, whereas long glass fibre-reinforced polypropylene exhibited fracture as leaf spring failure. Fatigue performance as well as failure morphology of the leaf springs confirmed the role of reinforced fibre length in the thermoplastic composite leaf spring.

This study aimed to evaluate 2 advanced methods for presurgical calculation of bilateral alveolar cleft defect volume using 3-dimensional (3D) printing and computer-aided engineering (CAE) software. Twelve patients with bilateral alveolar cleft (4 females, 8 males, age range 8-11 years) were enrolled in the study. All patients underwent preoperative helical computed tomography scans, and the digital imaging and communications in medicine (DICOM) data of the computed tomography images were analyzed using 3D printing and CAE software. The 3D-printed model used a simulated graft, and graft volume was measured by water displacement. The CAE software used a subtractive method to calculate volume. Simulated graft volumes and CAE-software-derived volumes were compared using Pearson's correlation test and paired Student's t-test. The average volume of the simulated bone grafts obtained using 3D-printed models was 1.45 mL, which was lower than the CAE-software-derived mean volume of 1.52 mL. The mean calculation time using the 3D-printed model was 51.5 minutes, which was 32.1 minutes longer than the average 19.4 minutes when using CAE software. Paired Student's t-test revealed no statistically significant difference between the volumes derived from these methods. The results of this study further validated the use of 3D printing and CAE technique in bilateral alveolar defect repair. The CAE software is more cost-effective in presurgical volumetric assessment. Moreover, 3D models overcome limitations of 3D visualizations by providing tactile feedback and superior appreciation of visuospatial relationships among anatomical structures.

A framework is formulated for the design and development of a user friendly CAE (computer aided engineering) package for drive system dynamics. The authors describe the design principles and algorithms of such a modular CAE package and its implementation on a personal computer. An effort has been made to fill the need for an interactive simulation to assess the torque ripple, losses, efficiency, torque and speed responses, and their bandwidth, as well as the suitability of the drive system for a specific application. One such CAE package, PMBD, has been developed, and key results using the package are presented to highlight the implemented features. Various user friendly features and dynamic and steady-state analysis results are described in detail. >

A parametric model is created in ANSYS workbench, FEA method is used to carry out probabilistic design in ANSYS workbench. Mono leaf spring is considered for analysis purpose and analysis is carried out. Composite material is applied to parametric model. Boundary conditions are applied to mono leaf spring, both ends are fixed and load (force) is applied to mono leaf spring. Meshing is carried out. The geometric parameters (thickness, width, etc.) are used as input parameter and Von-Mises stress considered as output parameter. For any further uncertainty in analysis, parametric co-relation function is used in ANSYS. The relation in geometric parameter and output parameter is achieved by correlation coefficients

This research article deals with a modified version of leaf spring suspension system introduced for the optimization of existing leaf spring suspension system design, by the combination of two helical springs with the master leaf. To furnish this end, a semi-elliptical type mono leaf spring of light weighted mini truck is considered for design and modeling work. On both the sides of this mono leaf, a helical spring is designed and modeled at equal distances from the center of leaf. All the modeling and analysis work is performed in CATIAV5R20. Stress analysis results at various loading conditions are obtained by both theoretical and FEA methods, separately for typical mono leaf spring model and proposed model with helical springs. Results show an average 8.3% stress reduction for any of the loading conditions, by the utilization of helical springs with the combination of master leaf. The proposed work have some certain benefits which could definitely transform the existing leaf spring design into a more optimized, stable and flexible one for the overall better performance and comfort to passengers. Cite this Article Sachin Gayakwad, Pushpendra Kumar Mishra, Ishan Patel. Stress Analysis of Leaf Spring Suspension System with the Combination of Helical Springs. Journal of Automobile Engineering and Applications. 2017; 4(3): 6–18p. Keywords: Leaf spring, helical spring, FEA, stresses, CATI

Design and analysis of composite mono leaf spring for passenger cars

<div class="section abstract"><div class="htmlview paragraph">Vehicle suspension systems that adopt Hotchkiss layout are commonly based on leaf springs. For better comfort for passengers, some features such as rubber pads are used on the springs to reduce noise from metallic contact between leaves, but those pads can compromise the durability of the spring if not well designed or located in the spring assembly, as we will demonstrate on this paper. To do so, it will be presented comparisons using CAE methodology and physical parts test results from vehicle and bench testing which were loaded in different conditions to demonstrate how the rubber pad position can influence the durability of the spring, especially near the eyelet region for some specific load conditions. The case studies presented here are focused on the impact of the rubber pads on durability life of springs, but not defined as root cause of failures.</div></div>

In vehicle multi-body dynamics (MBD) modeling, the stiffness parameterization of leaf spring (LS) is an unavoidable challenge regardless of the selection of modeling methods. On the contrary, the parameterization of Coil Spring (CS) stiffness is easy to achieve by adjusting the scale factor. Therefore, a novel LS stiffness parameterization method by treating the suspension stiffness as an intermediate variable through a CS stiffness is proposed based on the virtual displacement theory. The proposed method is then implemented in the vehicle-level modeling of a commercial Van with front transverse leaf spring suspensions and rear longitudinal parabolic leaf spring suspensions. The MBD model is validated by natural frequency tests and suspension stiffness simulations. Furthermore, the vertical acceleration of the car body is also verified. Results show that the root mean square (RMS) values of body vertical acceleration in the equivalent CS model are just slightly lower than that in the LS suspensions. The applicability and capability of the proposed method are proven to address the limitation of LS stiffness parameterization in MBD modeling. It lays the groundwork for efficiently simulating the LS suspension in vehicle ride and handling design and optimization.

Carbon fibre-reinforced polymer (CFRP) laminates are replacing traditional materials in numerous applications in which high specific strength and stiffness are sought. One example could be the use of composite leaf springs for lightweight structures in transport, which should be designed taking into account their bending response. The main objective of this work is to study analytically and numerically the influence of the geometry on the mechanical response of a mono leaf spring under the hypothesis of linear behaviour. With this scope, the performance of a CFRP mono leaf spring is observed considering four different geometries: cubic, parabolic, arc of circumference and elliptical. A linear-elastic study is carried out to examine the influence of the spring shape on its flexural behaviour in terms of the load transfer as well as the apparent bending rigidity, natural frequency and buckling load. Three-point bending tests are performed with parabolic specimens manufactured from unidirectional CFRP laminates for validating the assumption of linear response for three different thicknesses of the cross-section. The experimental results confirm the linear-elastic response of the samples, what allows theoretically estimating the stiffness and the stress state of the spring.

In a ubiquitous computing environment, computer-aided engineering (CAE) software packages can be encapsulated as a service and be accessible through networks, which is essential to small and medium enterprises (SMEs) for complex product design with limited computing resources. In this paper, a web service-based platform for the multi-disciplinary collaborative simulation (MDCSS) is proposed, which is a software-sharing environment. In MDCSS, although the CAE software packages reside in their remote application program servers, they are registered in the service center to be accessible according to the computing requests. Given the increasing CAE services with the same function, a quality of service (QoS)-aware scheduling method with real-time and countable parameters is proposed to adaptively select the most efficient web service among alternatives. Through an additional layer and an application broker for service scheduling, MDCSS allows allocating services automatically, keeping load balance, and minimizing human intervention. This platform is reusable, scalable, and efficient for implementation, which enables the end user to invoke the remote CAE software ubiquitously in a “pay-as-you-use” fashion.

The taper leaf spring of tandem suspension of commercial vehicle is different from the traditional taper leaf spring. Thus, the professional software MSC.ADAMS/CHASSIS leaf spring, which is specially applied in traditional leaf spring, does not reliably develop the computational model of the taper leaf spring of tandem suspension. The multi-body dynamic model of the taper leaf spring of tandem suspension, which is developed in this paper, is a secondary development model that is based on the leaf spring model built by MSC.ADAMS/CHASSIS leaf spring. End contact and friction in the modified model are redefined to exhibit the hysteretic characteristics of the taper leaf spring of tandem suspension. The test of the taper leaf spring of tandem suspension is conducted to validate the reliability of the modified model. The tests in this paper are divided into two groups. The first group started at an unloaded state at an excitation frequency of 1/30 Hz and amplitude of 70 mm to acquire quasi-static behavior. The second group is conducted at various frequencies (2, 3 and 4 Hz) and various amplitudes (±1, ±3 and ±10 mm) in a loaded state to acquire dynamic behavior. A formula to calculate dynamic spring rate for leaf spring is proposed, and details about the formula are presented. The simulations are conducted under the same conditions as the test. The hysteretic characteristics and the relative error of dynamic spring rate from the test are compared with the ones from the simulations for the validation of the reliability of the modified model.

Standardization is intended to overcome the last hurdle in the integration of computer aided software engineering (CASE) in an open system environment. Since there are numerous CASE and CASE related standard efforts currently under development on national and international levels, there is a wide spectrum of overlapping CASE standards research that must be identified and evaluated as to its specific present and future implications. Primarily the effects of CASE standards as they pertain to CASE vendors and users are discussed, along with the integration options of modern system development environments. >