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Hydraulic engine mounts are used in the automotive industry because they offer frequency and amplitude response characteristics superior to the conventional elastomeric engine mount. This response is well established but is not fully understood. Numerous articles have attempted to explain the complex behavior of these mounts using linear theory. This paper uses the same linear models developed in previous papers, but offers a more fundamental explanation of the system response using these previously derived two degree of freedom models. In addition, the source of engine vibrations and their corresponding frequency ranges are explained in detail. Techniques borrowed from control systems are used to interpret system response and terminology used in the automotive industry to describe the behavior of hydraulic engine mounts is clarified. Validation of the two degree of freedom model is made by comparison with experimental data.

A previous paper on this topic presented the use of design of experiments (DOE) to evaluate the sensitivity of vehicle dynamics simulation of the postimpact motion of a vehicle that included high initial rotational rates. That investigation involved only one software package and thus was confined to one simulation model for the purposes of developing and refining the analysis method rather than including a variety of simulation models for broader application. This paper expands the application of the method to investigate the comparative behavior and sensitivity of several other vehicle dynamic simulation models commonly used in the field of crash reconstruction. The software packages included in the studies presented in this paper are HVE (SIMON and EDSMAC4), PC-Crash and VCRware. This paper will present the results of the study, conducted using DOE, involving these models.

In this third edition of Vehicle Accident Analysis & Reconstruction Methods, Raymond M. Brach and R. Matthew Brach have expanded and updated their essential work for professionals in the field of accident reconstruction. Most accidents can be reconstructed effectively using calculations and investigative and experimental data: the authors present the latest scientific, engineering, and mathematical reconstruction methods, providing a firm scientific foundation for practitioners. Accidents that cannot be reconstructed using the methods in this book are rare. In recent decades, the field of crash reconstruction has been transformed through the use of technology. The advent of event data records (EDRs) on vehicles signaled the era of modern crash reconstruction, which utilizes the same physical evidence that was previously available as well as electronic data that are measured/captured before, during, and after the collision.