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Since its creation in 2011 the Pre-Crash-Matrix (PCM) offers the possibility to observe the pre-crash phase until five seconds before crash for a wide range of accidents. Currently the PCM contains more than 8.000 reconstructed accidents out of the GIDAS (German In-Depth Accident Study) database and is enlarged continuously by more than 1.000 cases per year. Hence, a detailed investigation of active safety systems in real accident situations has been made feasible. The PCM contains all relevant data in database format to simulate the pre-crash phase until the first collision of the accident for a maximum of two participants. This includes the definition of the participants and their characteristics, the dynamic behavior of the participants as time-dependent course for five seconds before crash as well as the geometry of the traffic infrastructure. The digital sketch of the accident and information from GIDAS as well as from supplementary databases represent the main input for the simulation of the pre-crash phase of an accident with the VUFO simulation model VAST (Vufo Accident Simulation Tool). This simulation in turn embodies the foundation of the PCM. The PCM underlies continual improvements and enhancements in consultation with its users. In addition to collisions of cars with other cars, pedestrians, bicycles and motorcycles the PCM now also covers car to object and car to truck collisions. The paper illustrates car to truck collisions as a showcase and explains perspectives for further developments. In 2016 a more detailed definition of the contour of the vehicle was added. Furthermore, the geometrical surroundings of the accident site will be provided in a new structure with a higher level of detail. Thus, a precise classification of road marks and objects is possible to further improve the support of developing and evaluating ADAS. This paper gives an overview about the latest developments of the PCM with its innovations and provides an outlook to upcoming enhancements. Besides potential areas of application for the development of ADAS are shown.
The advent of active safety systems calls for the development of appropriate testing methods. These methods aim to assess the effectivity of active safety systems based on criteria such as their capability to avoid accidents or lower impact speeds and thus mitigate the injury severity. For prospective effectivity studies, simulation becomes an important tool that needs valid models not only to simulate driving dynamics and safety systems, but also to resolve the collision mechanics. This paper presents an impact model which is based on solving momentum conservation equations and uses it in an effectivity study of a generic collision mitigation system in reconstructed real accidents at junctions. The model assumes an infinitely short crash duration and computes output parameters such as post-crash velocities, delta-v, force directions, etc. and is applicable for all impact collision configurations such as oblique, excentric collisions. Requiring only very little computational effort, the model is especially useful for effectivity studies where large numbers of simulations are necessary. Validation of the model is done by comparison with results from the widely used reconstruction software PC-Crash. Vehicles involved in the accidents are virtually equipped with a collision mitigation system for junctions using the software X-RATE, and the simulations (referred to as system simulations) are started sufficiently early before the collision occurred. In order to assess the effectivity, the real accident (referred to as baseline) is compared with the system simulations by computing the reduction of the impact speeds and delta-v.
Vorgestellt werden Ergebnisse aus der Untersuchung "Vergleich verschiedener Modellierungsprogramme zur Berechnung von Luftschadstoffen". Die Untersuchung wurde begleitend zu der Pilotstudie "NO2-Reduktion an Ti02-dotierten Lärmschutzwänden (LSW) an der A1" durchgeführt. Projektziel war der Vergleich von drei Ausbreitungsmodellen sowie die Auswahl eines geeigneten Modells für ein zu entwickelndes Online-Monitoring-System. Es wurde festgestellt, dass sich die Modellergebnisse infolge der Umsetzung kleinräumiger Details unterscheiden sowie dass alle Modelle lediglich geringe NOx-Minderungen in Folge der katalytischen Oberflächenbeschichtung anzeigen. In den numerischen Modellen wird die photokatalytische Wirkung der Ti02-beschichteten Lärmschutzwand über einen Depositionsprozess berücksichtigt. Unter Berücksichtigung der Hintergrundbelastung und der NOx-NO2-Umwandlung würde sich die Wirkung des Katalysators im Maximum auf weniger reduzieren. Die Messungen zeigten keine eindeutige Wirkung bezüglich der Immissionskonzentrationen im Bereich der beschichteten beziehungsweise unbeschichteten LSW an.
Vorgestellt werden Vorgehensweise, Datenaufbereitung, Modellaufbau und Ergebnisse des BASt-Projekts "Numerische Simulation der Stickoxidminderung durch photokatalytische Oberflächen an Verkehrswegen". Die Vorteile des Konzepts liegen in der Berücksichtigung von Zeitreihen (Eingangsdaten, Ausbreitungsrechnung) und in der Tatsache, dass die Depositionsgeschwindigkeit als zeitlich variable Eingangsgröße bei der Modellierung berücksichtigt wurde. Die Ergebnisse liegen entsprechend als Zeitreihen vor (Jahres- oder Tagesgänge können untersucht werden). Es ergab sich eine Minderung der NO2-Belastung um maximal knapp 1.5% im Nahbereich der Lärmschutzwand. Wesentlicher Faktor bei der Wirksamkeit photokatalytischer Oberflächen ist die Interaktion zwischen Gesamtbelastung und Depositionsgeschwindigkeit im Tagesverlauf.
Mit Fokus auf Nordrhein-Westfalen (NRW) wird das urbane NO2-Problem umrissen. Um die Jahresgrenzwerte einzuhalten, sind beispielsweise in allen Straßenschluchten in NRW Reduktionen nötig. Die Europäische Kommission hat gegen mehrere Mitgliedsstaaten, darunter Deutschland, Vertragsverletzungsverfahren wegen der Überschreitung von NO2-Grenzwerten eröffnet. Dargestellt werden die Langzeittrends bezüglich der gemessenen Abnahme bei der Stickoxidbelastung. Potenzielle Maßnahmen können hinsichtlich ihrer möglichen Wirkungen durch den Einsatz von Modellen abgeschätzt werden, zum Beispiel Umweltzonen, Fahrverbote, Elektrofahrzeuge. Die Ergebnisse der Messungen und Modellrechnungen werden dargestellt und kritisch beleuchtet. Als Fazit ergibt sich, dass das urbane NO2-Problem nicht einfach zu lösen ist, Minderungen der NOx-Emissionen spiegeln sich nicht in der gleichen Größenordnung in der Abnahme der NO2-Belastung wieder. Bei zusätzlich wirksamen Maßnahmen wie beispielsweise einem höheren Anteil von Elektrofahrzeugen fehlt die (schnelle) praktische Umsetzbarkeit. Eine Kombination aus lokalen, regionalen und europaweiten Maßnahmen ist nötig, um das Problem zu lösen.
The main focus of the benefit estimation of advanced safety systems with a warning interface by simulation is on the driver. The driver is the only link between the algorithm of the safety system and the vehicle, which makes the setup of a driver model for such simulations very important. This paper describes an approach for the use of a statistical driver model in simulation. It also gives an outlook on further work on this topic. The build-up process of the model suffices with a distribution of reaction times and a distribution of reaction intensities. Both were combined in different scenarios for every driver. Each scenario has then a specific probability to occur. To use the statistical driver model, every accident scene has to be simulated with each driver scenario (combinations of reaction times and intensities). The results of the simulations are then combined regarding the probabilities to occur, which leads to an overall estimated benefit of the specific system. The model works with one or more equipped participants and delivers a range for the benefit of advanced safety systems with warning interfaces.
Detailed anthropometric data of pregnant women have been collected and used in the development of a computational model of the pregnant occupant model "Expecting". The model is complete with a finite element uterus and multi-body fetus, which is a novel feature in the models of this kind. The computational pregnant occupant model has been validated and used to simulate a range of impacts. The strains developed in the utero-placental interface are used as the main criteria for fetus safety. Stress distributions due to inertial loading of the fetus on the utero-placental interface play a role on the strain levels. Inclusion of fetus model is shown to significantly affect the strain levels in the utero-placental interface. This series of studies has led to the design of seatbelt features specifically for the pregnant women to enable them use the seatbelt correctly and comfortably.
This study aimed at prediction of long bone fractures and assessment of lower extremity injury mechanisms in real world passenger car to pedestrian collision. For this purpose, two pedestrian accident cases with detail recorded lower limb injuries were reconstructed via combining MBS (Multi-body system) and FE (Finite element) methods. The code of PC Crash was used to determine the boundary conditions before collision, and then MBS models were used to reproduce the pedestrian kinematics and injuries during crash. Furthermore, a validated lower limb FE model was chosen to conduct reconstruction of injuries and prediction of long bone fracture via physical parameters of von Mises stress and bending moment. The injury outcomes from simulations were compared with hospital recorded injury data and the same long bone fracture patterns and positions can be observed. Moreover, the calculated long bone fracture tolerance corresponded to the outcome from cadaver tests. The result shows that FE model is capable to reproduce the dynamic injury process and is an effective tool to predict the risk of long bone fractures.
Since a number of human models have been developed it appears sensible to use these models also in the accident analysis. Especially the understanding of injury mechanisms and probably even injury risk curves can be significantly improved when interesting accidents are reconstructed using human body models. However, an important limitation for utilising human models for accident reconstruction is the effort needed to develop detailed FE models of the accident partners or to prepare the human model reconstruction by running physical accident reconstructions. The proposed approach for using human models for accident reconstruction is to use simplified and parametric car models. These models can be adapted to the crash opponents in a fast and cost effective way. Although, accuracy is less compared to detailed FE models, the relevant change in velocity can be simulated well, indicating that the computation of a detailed crash pulse is not needed. Two frontal impact test accidents that were reconstructed experimentally and using the parametric car models are indicating sufficient correlation of the adapted parametric car models with the full scale crash reconstructions. However, further developments of the parametric models to be capable for the use in lateral impacts and rear impacts are needed. For the PC Crash simulation runs the output sampling rate is too large to allow sufficient analysis. In addition the performance appears to be too general.
For the estimation of the benefit and effect of innovative Driver Assistance Systems (DAS) on the collision positions and by association on the accident severity, together with the economic benefit, it becomes necessary to simulate and evaluate a variety of virtual accidents with different start values (e.g. initial speed). Taken into account the effort necessary for a manual reconstruction, only an automated crash computation can be considered for this task. This paper explains the development of an automated crash computation based on GIDAS. The focus will be on the design of the virtual vehicle models, the method of the crash computation as well as exemplary applications of the automated crash computation. For the first time an automated crash computation of passenger car accidents has been realized. Using the automated crash computation different tasks within the field of vehicle safety can be elaborated. This includes, for example, the calculation of specific accident parameters (such as EES or delta-V) for various accident constellations and the estimation of the economic benefit of DAS using IRFs (Injury Risk Functions).
Real world accident reconstruction with the Total Human Model for Safety (THUMS) in Pam-Crash
(2013)
Further improvement of vehicle safety needs detailed analysis of real world accidents. According to GIDAS (German In-Depth Accident Study) most car to car front accidents occur at mid-crash severity. In this range thoracic injuries already occur. In this study a real world frontal crash with mid-crash severity out of the AARU database was reconstructed. The selected car to car accident was reconstructed by AARU by means of pc-crash software in order to get the initial dynamic accident conditions. These initial conditions were used to reconstruct the complete accident in more detail using FE models for the car structure and the occupants. Occupant simulations were performed with FE HIII-dummy models and the THUMS using Pam-Crash code. An initial THUMS validation was performed in order to verify the model-´s biofidelity by means of table-top test simulations. THUMS bone stiffness values were modified to match the real word occupant age. A comparison between driver and passenger restraint system loading was done, as well as an injury prediction comparison between the HIII-dummy model and THUMS response for both cases. Detailed comparison between the HIII-dummy models and THUMS regarding thoracic loading are discussed.
Among European Countries, Spain first issued a Standard, UNE 135900:2005, further updated in 2008, that deals with homologation and effectiveness evaluation of road restraint systems components designed to reduce harm for bikers impacting on them. An in depth analysis and critical review of this standard is reported in this paper. Beside a close examination of the standard requirements, numerical models of the crash test stated by the standard have been set up and simulated to study the effects of slight speed and approach angle variations on test results, remaining within tolerance gaps allowed by the standard. Model were validated against experimental data. Together with the expected increasing severity of the impact according with speed, a strong influence of approach angle on injury parameters was found. Possible improvements to the norm, in order to make it more robust, are suggested.
Im Beitrag wird über Rissbildungen in orthotropen Fahrbahnplatten, die im "Schubzahn" des Querträgerstegblechs von den Anschlussschweissnähten trapezförmiger Längsträger ausgehen, berichtet. Der Rissausgangspunkt liegt im Bereich der Ausnehmung des Querträgersteges für die durchlaufenden Längsträger. Durch Optimierung der Querträgerausnehmung und örtliche Verstärkung (Aufpflasterung) des Querträgerstegblechs im Bereich des Schubzahnes soll eine dauerhafte Instandsetzung der aufgetretenen Schäden ermöglicht werden. Durch genauere numerische und versuchstechnische Untersuchungen soll diese Aussage untermauert werden. Einzelheiten der bereits durchgeführten Untersuchungen werden mitgeteilt.