FIMCAR XIV: Potential of Simulation Tools

For the assessment of vehicle safety in frontal collisions compatibility (which consist of self and partner protection) between opponents is crucial. The use of simulation tools is the only way to a realistic and wide coverage (w.r.t. the real accident situations that may happen on the road) of car-to-car compatibility issues with acceptable costs. This report reviews the use of Virtual Testing (VT) in today’s European vehicle and product type approval, and the on-going work for future implementation of VT in vehicle type approval and rating. The modelling requirements and validation process are discussed both regarding barrier models and car models. Combined with the experience from the use of simulation tools in the FIMCAR project, a 4-step roadmap for implementation of VT tools in the compatibility development is proposed

Future perspectives on automotive CAE

Computer Aided Engineering (CAE) is an integral part of today’s automotive design process. Very often OEM’s rely solely on software vendors to provide appropriate solutions. On the other hand, some companies still use in-house developed software for specific applications. It is, however, a combination of these two approaches that provides OEM’s with optimal leading edge software technology. This paper will present an overview of several relevant automotive CAE-methods that will illustrate this approach. Four important automotive software areas will be considered: vehicle CFD applications, aeroacoustics, vehicle crash analysis and occupant / pedestrian safety. The first two topics, CFD and aeroacoustics, are extensive subject areas in themselves, but will be dealt with by considering two specific topics, namely, numerical aerodynamic / flow optimization and aeroacoustic sound propagation into vehicle cabins, respectively. A more detailed focus will be placed on the two safety application areas: vehicle crash analysis and occupant safety using Human Body Models

Damage and failure modelling of carbon and glass 2D braided composites

Composite materials have been increasingly used in the past two decades since they offer significant potential weight reduction, part design flexibility and improved specific mechanical performance compared to traditional metals. For specific applications, braid reinforced composites offer better near net shape part and manufacturing flexibility than conventional unidirectional laminates, albeit at the expense of slightly lower in-plane stiffness and strength. Furthermore, for impact and crash applications, which is the emphasis of this thesis, their tow waviness and interlocking can offer excellent damage tolerance and energy absorption. In this work, heavy tow (24k) biaxial carbon and glass braided preforms were used to manufacture coupons and beam structures to undertake an extensive testing campaign to characterise different damage and failure mechanisms occurring in braided composites. Due to large shear deformation and surface degradation, non conventional measurement techniques based on marker tracking and Digital Image Correlation were successfully used to measure strains in the damaging material. The modelling of braided composites was conducted using the meso-scale damage approach first proposed by P. Ladevèze for unidirectional composites. The calibration of an equivalent braid unidirectional ply was achieved using the experimental results obtained for different braided coupons. Furthermore, failure mechanisms observed experimentally, such as tow stretching and fibre re-orientation occurring during loading history, were integrated into the model. A new unidirectional ply formulation was subsequently implemented into the explicit finite element code PAM-CRASHTM. Validation of the new model using single element, coupons and beams were conducted that provided a satisfying correlation between experimental tests and numerical predictions

FIMCAR I: Summary report

The goal of the FIMCAR (Frontal Impact and Compatibility Assessment Research) project was to propose a frontal impact assessment approach addressing self- and partner protection. Research strategies and priorities were based on earlier research programs and the FIMCAR accident data analysis looking at modern cars. The identified real world safety issues – such as structural interaction (especially under-/override), high acceleration loading of the occupant especially in large overlap accidents and insufficient horizontal and vertical load spreading were used for evaluating the different test candidates. In addition to the issues mentioned above, the FIMCAR accident analysis suggested that frontal force compartment integrity matching is less of an issue as originally expected. FIMCAR developed a car-to-car test program that investigated the performance of vehicle structures. Results of the test program show that the presence of a lower load path contributes to a more robust performance of the vehicle. The rearward offset of a lower load path could be reviewed and used to quantify when a lower structure design can contribute to structural interaction in both frontal and side impact configurations. In addition to the car crash test programme, numerical models of actual cars and barriers were developed and used. As car-to-car simulations with models of different car manufacturers are almost impossible because of confidentiality, Parametric Car Models (PCM) and Generic Car Models (GCM) were developed. Due to the parametric design of the PCMs it is possible to modify the models in an easy and fast way. The GCMs model virtual cars which represent an average real car of the respective category in a comparable way to the OEM models. Within the FIMCAR project, different frontal impact test candidates were analysed regarding their potential for future frontal impact legislation. The research activities focused on car-tocar frontal impact. Test procedures were developed with both a crash test programme and numerical simulations. This analysis resulted in the combination of the Full Width Deformable Barrier test (FWDB) with compatibility metrics and the existing Offset Deformable Barrier (ODB) as described in UN-ECE Regulation 94 with additional cabin integrity requirement as being proposed as the FIMCAR assessment approach. The advantages of the FWDB compared to the rigid wall are the more representative pulse and deformation pattern as well as the better assessment of load paths. The introduction of a (M)PDB without compatibility metrics (that FIMCAR was unable to deliver in time) was considered as not being appropriate. The proposed frontal impact assessment approach addresses many of the issues identified by the FIMCAR consortium (impact alignment, high acceleration pulse loading, maintenance of compartment strength requirements, etc.) but not all frontal impact and compatibility issues could be addressed (load spreading).A benefit analysis estimated the benefit of the following three options: no change, introduction of full width test with compatibility assessment in addition to current ECE R94 and introduction of full width test with compatibility assessment and replacement of current ODB test by PDB test with load spreading metric. The comparison of calculated break even costs for option 2 with estimated costs for achieving the benefit from previous projects suggests a positive cost benefit ratio

Temporospatial Context-Aware Vehicular Crash Risk Prediction

With the demand for more vehicles increasing, road safety is becoming a growing concern. Traffic collisions take many lives and cost billions of dollars in losses. This explains the growing interest of governments, academic institutions and companies in road safety. The vastness and availability of road accident data has provided new opportunities for gaining a better understanding of accident risk factors and for developing more effective accident prediction and prevention regimes. Much of the empirical research on road safety and accident analysis utilizes statistical models which capture limited aspects of crashes. On the other hand, data mining has recently gained interest as a reliable approach for investigating road-accident data and for providing predictive insights. While some risk factors contribute more frequently in the occurrence of a road accident, the importance of driver behavior, temporospatial factors, and real-time traffic dynamics have been underestimated. This study proposes a framework for predicting crash risk based on historical accident data. The proposed framework incorporates machine learning and data analytics techniques to identify driving patterns and other risk factors associated with potential vehicle crashes. These techniques include clustering, association rule mining, information fusion, and Bayesian networks. Swarm intelligence based association rule mining is employed to uncover the underlying relationships and dependencies in collision databases. Data segmentation methods are employed to eliminate the effect of dependent variables. Extracted rules can be used along with real-time mobility to predict crashes and their severity in real-time. The national collision database of Canada (NCDB) is used in this research to generate association rules with crash risk oriented subsequents, and to compare the performance of the swarm intelligence based approach with that of other association rule miners. Many industry-demanding datasets, including road-accident datasets, are deficient in descriptive factors. This is a significant barrier for uncovering meaningful risk factor relationships. To resolve this issue, this study proposes a knwoledgebase approximation framework to enhance the crash risk analysis by integrating pieces of evidence discovered from disparate datasets capturing different aspects of mobility. Dempster-Shafer theory is utilized as a key element of this knowledgebase approximation. This method can integrate association rules with acceptable accuracy under certain circumstances that are discussed in this thesis. The proposed framework is tested on the lymphography dataset and the road-accident database of the Great Britain. The derived insights are then used as the basis for constructing a Bayesian network that can estimate crash likelihood and risk levels so as to warn drivers and prevent accidents in real-time. This Bayesian network approach offers a way to implement a naturalistic driving analysis process for predicting traffic collision risk based on the findings from the data-driven model. A traffic incident detection and localization method is also proposed as a component of the risk analysis model. Detecting and localizing traffic incidents enables timely response to accidents and facilitates effective and efficient traffic flow management. The results obtained from the experimental work conducted on this component is indicative of the capability of our Dempster-Shafer data-fusion-based incident detection method in overcoming the challenges arising from erroneous and noisy sensor readings

CAMAC bulletin: A publication of the ESONE Committee Issue #12 April 1975

CAMAC is a means of interconnecting many peripheral devices through a digital data highway to a data processing device such as a computer

Towards ServMark, an Architecture for Testing Grid Services

Technical University of Delft - Technical Report ServMark-2006-002, July 2006Grid computing provides a natural way to aggregate resources from different administrative domains for building large scale distributed environments. The Web Services paradigm proposes a way by which virtual services can be seamlessly integrated into global-scale solutions to complex problems. While the usage of Grid technology ranges from academia and research to business world and production, two issues must be considered: that the promised functionality can be accurately quantified and that the performance can be evaluated based on well defined means. Without adequate functionality demonstrators, systems cannot be tuned or adequately configured, and Web services cannot be stressed adequately in production environment. Without performance evaluation systems, the system design and procurement processes are limp, and the performance of Web Services in production cannot be assessed. In this paper, we present ServMark, a carefully researched tool for Grid performance evaluation. While we acknowledge that a lot of ground must be covered to fulfill the requirements of a system for testing Grid environments, and Web (and Grid) Services, we believe that ServMark addresses the minimal set of critical issues