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With the widespread availability of personal computers in the recent past, authors decided to develop a powerful and efficient algorithm to design an optimal leaf spring for a light or heavy truck where the desired objective is the minimum weight of the spring or the spring rate. It is based on the non-linear optimization technique called Lattice Search Method. The software developed is called “YOU HUA” (Chinese for optimization). The computer program has been written using TURBO PASCAL 5.0 for the optimum design solution of the leaf spring. Three types of springs can be designed: symmetrical semi-elliptic, unsymmetrical semi-elliptic and multi-leaf cantilever springs. Some examples are done to illustrate the application of this software. It is concluded that this technique is useful to design an optimal leaf spring with a high level of efficiency and accuracy. This work is a definite contribution in the process of leaf spring design without trial and error.

Knowledge of the loads experienced by a leaf spring suspension is required for the optimal design of the suspension components and frame. The most common method of representing leaf springs is the SAE 3 link model, which does not give good results in the lateral direction. In this paper, a beam element leaf spring model is developed. This model is validated using data obtained from laboratory tests done on leaf spring assemblies. The model is then subjected to actual road load data measured on the Proving Ground. Lastly, results from the beam element model are presented and compared with results obtained from proving ground tests. Overall, the beam element model gives good results in all directions except in situations where it is subjected to high fore/aft acceleration and high reverse braking events.

Mode management is an essential part of the design process for NVH performance. System resonances must be sufficiently separated to minimize interaction from source inputs and each other [1]. Such resonances are typically determined through experimental modal testing conducted in a lab environment under controlled and repeatable conditions. Global vehicle and suspension system response demonstrate soft nonlinear behavior, however. Their resonant frequencies may thus decrease under on-road input not reproducible in a lab environment. Subsequently, mode management charts derived from lab testing may not be representative of the vehicle's on-road dynamic response. This paper presents modal model determination methodologies, and examines suspension system and vehicle global dynamic response under lab modal test and operating conditions. Vehicle suspension modes measured under static and dynamic (rolling) conditions will be compared.

This paper dis cusses the development of a nonlinear shock absorber model for low-frequency CAE-NVH applications of body-on-frame vehicles. In CAE simulations, the shock absorber is represented by a linear damper model and is found to be inadequate in capturing the dynamics of shock absorbers. In particular, this model neither captures nonlinear behavior of shock absorbers nor distinguishes between compression and rebound motions of the suspension. Such an inadequacy limits the utility of CAE simulations in understanding the influence of shock absorbers on shake performance of body-on-frame vehicles in the low frequency range where shock absorbers play a significant role. Given this background, it becomes imperative to develop a shock absorber model that is not only sophisticated to describe shock absorber dynamics adequately but also simple enough to implement in full-vehicle simulations. This investigation addresses just that.

The dampers of semi-active vehicle suspensions have a limited working region. They are only capable of delivering control force in phase with damper contraction/expansion. Without special measures the delivered control force may be switched on and off abruptly at the entering/exiting of the damper working region. This causes deterioration of ride comfort quantified by the derivative of vehicle body acceleration (jerk). Proposed is a control algorithm modification for smooth force transition at the borders of the damper working region. A time based force modulation is used. A predictor of the time to exiting the working region is proposed to lower requested force in advance. A hybrid controller is investigated combining level and time based force modulation.

Deep drawing is a sheet metal forming process in which metal blank is radially drawn into a forming die by the mechanical action of the punch. Dimensional tolerances and their variations are important aspects of quality control issues in this forming operation. In this regard, the spring-back effect is an inherent phenomenon that directly affects the final dimensions of the part produced. This research work is focused on analysis and control of spring-back in deep drawing processes. It is mainly focused on design and implementation/simulation of control strategies to minimize that. In this regard, the impact of various process parameters such as lubrication, punch speed, punch and die nose radius, and blank holding force is studied through design of experiment methodology. In particular, this study is focused on the design and development of various control strategies to minimize spring back in this process. An experimental set up is designed and developed to facilitate this research.

In this study, a full vehicle with durability tire model established with ADAMS is applied to simulate the dynamic behavior of the vehicle under severe rough road proving ground events, where the shock force-velocity characteristics are modeled as nonlinear curves and multi-stage representations, respectively. The shock forces and velocities at each corner are resolved and through full factorial DOE, the shock forces and velocities response surface models are established to analyze the sensitivities of shock force and velocity to the shock damping characteristics.

In this paper, a comprehensive evaluation index for impact harshness (IH) is proposed. A mid-sized uni-body SUV is selected for this study, with the acceleration responses at the various vehicle body locations as objective functions. A sensitivity study is conducted using an ADAMS full vehicle model with flexible body structure representation over an IH event to analyze the influence of various suspension tuning parameters, including suspension springs, shock damping, steer gear ratio, unsprung mass, track-width, and bushing stiffness.

This paper deals with the dynamic characterization of an automotive shock absorber, a continuation of an earlier work [1]. The objective of this on-going research is to develop a testing and analysis methodology for obtaining dynamic properties of automotive shock absorbers for use in CAE-NVH low-to-mid frequency chassis models. First, the effects of temperature and nominal length on the stiffness and damping of the shock absorber are studied and their importance in the development of a standard test method discussed. The effects of different types of input excitation on the dynamic properties of the shock absorber are then examined. Stepped sine sweep excitation is currently used in industry to obtain shock absorber parameters along with their frequency and amplitude dependence. Sine-on-sine testing, which involves excitation using two different sine waves has been done in this study to understand the effects of the presence of multiple sine waves on the estimated dynamic properties.