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Technical Paper

The Practical Application of Finite Difference Analysis in Accident Reconstruction

The effective application of a Finite Difference Analysis routine in accident reconstruction is demonstrated. Such analysis finds not only the central value but the reliability side-bands; not only the mean but the probable extremes of the analysis, given the probable investigative reliability. ...Furthermore, because the controlling transfer functions depend only on the physics of the event, the side-band spans found by one means of reconstruction apply also to the central values found by some other means. Such ubiquity allows the practitioner to add to pre-existing central results the probable bounds of those results due to the practical limitations of investigative accuracy.
Journal Article

Probabilistic Reanalysis Using Monte Carlo Simulation

PRA calculates very efficiently the system reliability or the average value of an attribute of a design for many probability distributions of the input variables, by performing a single Monte Carlo simulation. In addition, PRA calculates the sensitivity derivatives of the reliability to the parameters of the probability distributions.
Journal Article

Managing the Computational Cost of Monte Carlo Simulation with Importance Sampling by Considering the Value of Information

Although it is significantly more efficient than standard Monte Carlo simulation if a suitable sampling distribution is used, in many design problems it is too expensive. ...The authors have previously proposed a method to manage the computational cost in standard Monte Carlo simulation that views design as a choice among alternatives with uncertain reliabilities.
Journal Article

Efficient Random Vibration Analysis Using Markov Chain Monte Carlo Simulation

Reliability assessment of dynamic systems with low failure probability can be very expensive. This paper presents and demonstrates a method that uses the Metropolis-Hastings algorithm to sample from an optimal probability density function (PDF) of the random variables. This function is the true PDF truncated over the failure region. For a system subjected to time varying excitation, Shinozuka's method is employed to generate time histories of the excitation. Random values of the frequencies and the phase angles of the excitation are drawn from the optimal PDF. It is shown that running the subset simulation by the proposed approach, which uses Shinozuka's method, is more efficient than the original subset simulation. The main reasons are that the approach involves only 10 to 20 random variables, and it takes advantage of the symmetry of the expression of the displacement as a function of the inputs. The paper demonstrates the method on two examples.
Technical Paper

Crush Energy in Accident Reconstruction

Vehicle accident reconstruction methods based on deformation energy are argued to be an increasingly valuable tool to the accident reconstructionist, provided reliable data, reasonable analysis techniques, and sound engineering judgement accompany their use. ...Vehicle accident reconstruction methods based on deformation energy are argued to be an increasingly valuable tool to the accident reconstructionist, provided reliable data, reasonable analysis techniques, and sound engineering judgement accompany their use. ...It is concluded that the deformation energy for an accident vehicle can be estimated using the CRASH model provided that test data specific to the accident vehicle is utilized.
Journal Article

Bootstrapping and Separable Monte Carlo Simulation Methods Tailored for Efficient Assessment of Probability of Failure of Structural Systems

Therefore, to account for the uncertainty, the safety of the system must be quantified using its reliability. Monte Carlo Simulation (MCS) is widely used for probabilistic analysis because of its robustness. ...Smarslok et al. [2010] developed an improved sampling technique for reliability assessment called Separable Monte Carlo (SMC) that can significantly increase the accuracy of estimation without increasing the cost of sampling.
Journal Article

Estimation of One-Sided Lower Tolerance Limits for a Weibull Distribution Using the Monte Carlo Pivotal Simulation Technique

This paper introduces a methodology to calculate confidence bounds for a normal and Weibull distribution using Monte Carlo pivotal statistics. As an example, a ready-to-use lookup table to calculate one-sided lower confidence bounds is established and demonstrated for normal and Weibull distributions. ...Lieberman in 1958 (later modified by Link in 1985 and Wei in 2012), and has been widely used in the automotive industry because of the easy-to-use lookup tables. Monte Carlo simulation methods presented here are more accurate as they eliminate assumptions and approximations inherent in existing approaches by using random experiments.
Technical Paper

Spot Weld Failure Analysis for Accident Reconstruction

Adequacy of resistance spot welds in low carbon steels in relation to structural integrity can become an issue in the reconstruction of automotive accidents. Because formation of a plug (or button or slug) in a peel test is used as a quality control criterion for welds, it is sometimes assumed conversely that a weld which failed is defective if no plug is present.
Technical Paper

Impact Center and Restitution Coefficients for Accident Reconstruction

Based on a previously presented two-dimensional car-to-car impact model, automobile collision tests were analyzed to understand the relationship of the impact center to the residual vehicle deformation, which is essential for improving the reliability of the impact model. The results from a number of automobile collision tests indicated that the impact centers of the two vehicles at the end of collision were located near the center of the contacting surface when the vehicle deformation is maximized. This leads to a method of defining the impact center from the crush profile at the time of maximum deformation. The relationships of the normal and tangential restitution coefficients to the collision type were also presented, discussed and evaluated to obtain some guidelines on how to choose the restitution coefficients from impact conditions.
Technical Paper

Component and System Life Distribution Prediction Using Weibull and Monte Carlo Analysis with Reliability Demonstration Implications for an Electronic Diesel Fuel Injector

This paper presents a methodology to predict component and system reliability and durability. The methodology is illustrated with an electronic diesel fuel injector case study that integrates customer usage data, component failure distribution, system failure criteria, manufacturing variation, and variation in customer severity. Extension to the vehicle system level enables correlation between component and system requirements. Further, this analysis provides the basis to establish a knowledge-based test option for a success test validation program to demonstrate reliability.
Technical Paper

Improving Witness Contributions to Reconstruction and Animation

These historically vague summaries are severely limited for accident reconstruction or animation use. This paper reviews the reasons for witness communication difficulties and provides questioning techniques that will, in many instances, allow the investigator to extract data which is more consistent with physical facts and Newtonian physics. ...Which is more reliable? A reconstruction based on sound physical facts, eyewitness statements, or both? Eyewitness statements are usually opinions stated as facts, easily misinterpreted, and often misleading. ...This more accurate witness data can be used for developing effective testimony, reconstruction and animation.
Technical Paper

Some Aspects of Motorcycle-Vehicle Collision Reconstruction

A major difficulty in the reconstruction of motorcycle-vehicle collisions derives from the fact that the motorcycle-rider and the motorcycle itself execute in general different trajectories after a collision with another vehicle. ...Accordingly, certain assumptions which may vary from case to case have to be introduced in order that the momentum and energy balance approach which is usually applied for the purpose of collision reconstruction can be adapted to calculate pre-impact circumstances. However, due to the often unfavourable mass ratio an accurate reconstruction may be impeded. ...However, due to the often unfavourable mass ratio an accurate reconstruction may be impeded. A problem also exists in the assessment of post-crash decelerations of motorcycles because their motion patterns during that phase are often complex and not easily reconstructed.
Technical Paper

Analysis under Vehicle-Pedalcyclist Risk Scenario Based on Comparison between Real Accident and Naturalistic Driving Data

This paper constructs the Accident Crash Scenarios(ACSs) classification system based on the traffic accident data collected by the traffic management department in a Chinses city from 2013 to 2015. ...Driving Reliability and Error Analysis Method(DREAM) was used to analyze which induced factors are more likely to lead to accidents under the scenarios involved Car-Pedalcyclist in intersection. The result shows Too late actions and Too high speed are two induced factors of top two critical levels, Misjudgment and Expectance of certain behaviors are responsible for these two induced factors.