This study investigates the mechanical and geometrical attributes of egg–box energy absorbing structures as crash safety barriers in the automotive industry. The research herein was originated from the earlier work of Prof. Shirvani, patented and further investigated by Cellbond Composites Ltd. who has invested in further research, for developing an analytical tool for geometric optimisation as an enhanced resolution to various shapes and materials. Energy absorption in egg-box occurs through plastic deformation of cell walls, examined through non–linear finite element simulations using ANSYS® and ANSYS/LS–DYNA® FE packages. Experimental dynamic crash tests have been designed to verify the validity of the FE simulations. Geometrical models are defined as 3D graphical representations, outlined in detail. Further, the impact behaviour of commercially pure aluminium egg-box energy absorbers is studied to identify the optimum design parameters describing the geometry of the structure. A simulation-based multi-objective optimisation strategy is employed to find a set of Pareto-optimal solutions where each solution represents a trade-off point with respect to the two conflicting objectives: the maximum impact force and the energy absorption capacity of the structure. The aim is to simultaneously minimise the former and maximise the latter, in the attempt to find purpose–specific optimal egg–box geometries. In light of the associated outcomes, it is shown that egg–box geometries with < ω ), thin walls (t < 1mm), short inter–peak distances and small peak diameters. M – < ω ), thin walls (t < 1mm), lengthy inter–peak distances and smaller peak diameters. It is concluded that, egg–box structures combined in the form of sandwich panels can be designed per application to act as optimised energy absorbers. Results of the proposed optimised sandwich structure are verified using analytical techniques.

Det här examensarbetet genomfördes sommaren 2017 på Autoliv Test Center i Vårgårda. Autoliv är världens ledande leverantör av säkerhetsutrustning och utvecklare av säkerhetssystem för fordonsindustrin. Autoliv genomför även krockprovning för kunder som vill genomföra tester av deras bilar före produktion. Vid krockprovning accelereras testfordonet av en krockprovningstrolley som kopplar samman fordonet med en vajer vilket drivs genom ett hydrauliskt framdrivningssystem. Trolleyn är en stålkonstruktion som är placerad i krockspåret vilket griper fast i stålvajern med ett klämsystem. Krockprovningsindustrin är i ständig utveckling med nya säkerhetssystem, hårdare regler och tuffare krav från myndigheter och fordonssäkerhetsorganisationer. Ett nyligen introducerat test kallat NHTSA Oblique 90km/h hade svårt att genomföras på grund av att klämmekanismen slirat vid genomförandet. Målet med examensarbetet har varit att ta fram en ny krockprovningstrolley som fungerar när den genomför NHTSA Oblique 90km/h. Arbetet har varit inriktat på att designa en trolley som fungerar under nuvarande förhållanden utan att göra inverkningar på krockbanan eller framdrivningssystemet. Fyra koncept har designats i 3D, utvärderas i en konceptmatris, diskuterats med erfaren personal och ett koncept valdes ut för fortsatt utveckling. Effekterna av den nya designen på komponenter har undersökts och justeringar genomfördes. En FEM-analys gjordes på det vinnande konceptet för att bedöma hållfastheten på trolleyn samt potentialen för viktoptimering. Resultat var en ny trolleyplatta, 20 cm längre och 10mm tunnare. Den ursprungliga plattans vikt bevarades och designen rekommenderades av personal på ATC. Trolleyn diskuterades och ytterligare rekommendationer gavs. / This thesis was performed in the summer of 2017 at Autoliv Test Center in Vårgårda. Autoliv is the world’s leading automotive safety supplier and developer of safety equipment for the vehicle industry. Autoliv also performs crash testing for customers wanting their concept cars tested before production. In crash testing, the vehicle is accelerated by a crash track trolley that connects the vehicle to a steel wire driven with a hydraulic propulsion system. The trolley is a steel construction positioned inside the crash track gripping the wire with a clamping mechanism. The crash testing industry is in constant development due to new safety systems, harder regulations and tougher requirements from governments and vehicle safety organizations. A recently introduced crash test called the NHTSA Oblique 90km/h had issues being performed due to slip between the clamping system and steel wire. The goal of this thesis has been to develop a new crash track trolley that does not malfunction during crash testing. The work has been aimed at designing a trolley that functions at current conditions without implications on the crash track or propulsion system. Four concepts have been designed in 3D, evaluated in a concept matrix, discussed with senior staff and one concept was chosen for further development. The effects of the new design on components have been investigated and adjustments were made. A FEM-analysis was done on the winning concept to look into the physical integrity of the new trolley as well as the potentials in weight optimization. The result was a new trolley plate, elongated by 20 cm and thinned by 10 mm. The same plate weight was preserved and the trolley design was recommended by senior staff at ATC. The trolley was discussed and further recommendations were given.

The Utah Department of Transportation developed life-cycle benefit-cost analysis spreadsheets that allow engineers and analysts to evaluate multiple safety countermeasures. The spreadsheets have included the functionality to evaluate a roadway based on the 11 facility types from the Highway Safety Manual (HSM) with the use of crash severity distributions. The HSM suggests that local agencies develop crash severity distributions based on their local crash data. The Department of Civil and Environmental Engineering at Brigham Young University worked with the Statistics Department to develop crash severity distributions for the facility types from the HSM.The primary objective of this research was to utilize available roadway characteristic and crash data to develop crash severity distributions for the 11 facility types in the HSM. These objectives were accomplished by segmenting the roadway data based on homogeneity and developing statistical models to determine the distributions. Due to insufficient data, the facility types of freeway speed change lanes and freeway ramps were excluded from the scope of this research. In order to accommodate more roadways within the research, the facility type definitions were expanded to include more through lanes.The statistical models that were developed for this research include multivariate regression, frequentist binomial regression, frequentist multinomial, and Bayesian multinomial regression models. A cross-validation study was conducted to determine the models that best described the data. Bayesian Information Criterion, Deviance Information Criterion, and Root-Mean-Square Error values were compared to conduct the comparison. Based on the cross-validation study, it was determined that the Bayesian multinomial regression model is the most effective model to describe the crash severity distributions for the nine facility types evaluated.

Signalized Intersections on the State Roads in Hillsborough and Pinellas County, Florida with observed left turn lane overflow (spill) were selected for a safety and operational study. The study analyzed the crash data for safety hazards that the situation presents. Crashes within 100 feet from the center line of the crossroad of intersections under study to distances 200 feet beyond the end of the turn lane were chosen for the analysis. Left turn overflow is the situation at the approach of an intersection where left turning vehicles back up from the turn lane into the through traffic lane. Crashes within the intersection legs with the left turn lane overflow problems resulted in more crashes than the intersection legs without the spill problem at 95 percent confidence level. However the result was not overwhelming when 3 leg intersections are combined with 4 leg intersections. The rush periods within the leg of the intersection where left turn overflow occurred did not seem to have any correlation at all using paired t test.

In 2010, the American Association of State Highway and Transportation Officials (AASHTO) released a safety analysis software system known as SafetyAnalyst. SafetyAnalyst implements the empirical Bayes (EB) method, which requires the use of Safety Performance Functions (SPFs). The system is equipped with a set of national default SPFs, and the software calibrates the default SPFs to represent the agency’s safety performance. However, it is recommended that agencies generate agency-specific SPFs whenever possible. Many investigators support the view that the agency-specific SPFs represent the agency data better than the national default SPFs calibrated to agency data. Furthermore, it is believed that the crash trends in Florida are different from the states whose data were used to develop the national default SPFs. In this dissertation, Florida-specific SPFs were developed using the 2008 Roadway Characteristics Inventory (RCI) data and crash and traffic data from 2007-2010 for both total and fatal and injury (FI) crashes. The data were randomly divided into two sets, one for calibration (70% of the data) and another for validation (30% of the data). The negative binomial (NB) model was used to develop the Florida-specific SPFs for each of the subtypes of roadway segments, intersections and ramps, using the calibration data. Statistical goodness-of-fit tests were performed on the calibrated models, which were then validated using the validation data set. The results were compared in order to assess the transferability of the Florida-specific SPF models. The default SafetyAnalyst SPFs were calibrated to Florida data by adjusting the national default SPFs with local calibration factors. The performance of the Florida-specific SPFs and SafetyAnalyst default SPFs calibrated to Florida data were then compared using a number of methods, including visual plots and statistical goodness-of-fit tests. The plots of SPFs against the observed crash data were used to compare the prediction performance of the two models. Three goodness-of-fit tests, represented by the mean absolute deviance (MAD), the mean square prediction error (MSPE), and Freeman-Tukey R2 (R2FT), were also used for comparison in order to identify the better-fitting model. The results showed that Florida-specific SPFs yielded better prediction performance than the national default SPFs calibrated to Florida data. The performance of Florida-specific SPFs was further compared with that of the full SPFs, which include both traffic and geometric variables, in two major applications of SPFs, i.e., crash prediction and identification of high crash locations. The results showed that both SPF models yielded very similar performance in both applications. These empirical results support the use of the flow-only SPF models adopted in SafetyAnalyst, which require much less effort to develop compared to full SPFs.

The diploma thesis deals with the problem of speed determination during tangent collisions of two vehicles. The theoretical part describes the available literature and the preparation of an expert experiment. The practical part describes the experiment itself. Its results are processed and compared with the literature in the theoretical part. The aim of work is to extend knowledge about tangent collisions and reduce the error rate in determining crash in the expert analysis or claims in insurance companies.

This diploma thesis is devoted to the possibility of using materials for crash test dummy construction. The thesis describes how crash test dummies evolved, what crash test dummies are currently available for crash test and what they are made of. The main aim of the diploma thesis is to design materials and process for production of a crash test dummy with human-like biofidelity. The thesis describes the way which the dummy will be manufactured using duralumin, rubber, alder wood and silicone polymer or agar.

This diploma thesis analyses the influence of the change to the vehicle’s center of gravity on its after-impact movement. The theoretical part of the thesis describes the basic methods which are used in investigation of the transverse, lengthwise and height position of center of gravity or the influence of center of gravity’s vehicle position to its stability and handling. Next part of the thesis deals with basic division of the road accidents and briefly describes the methods used in its analysis. Problematic maneuvers and everyday road traffic situations are stated in this thesis. Chosen situations were simulated in Virtual CRASH and PC crash programmes. Influence of the transverse, lengthwise and height position of center of gravity was investigated in these programmes with regards to the after-impact behaviour of vehicle. The obtained results were evaluated in the final chapter.

This diploma thesis analyses the influence of the changes to the vehicle’s center of gravity on its after-impact movement. The theoretical part of the thesis describes the basic methods which are used in investigation of the transverse, lengthwise and height position of center of gravity or the influence of center of gravity’s vehicle position to its stability and handling. Next part of the thesis deals with basic division of the road accidents and briefly describes the methods used in its analysis. Problematic maneuvers and everyday road traffic situations are stated in this thesis. Chosen situations were simulated in Virtual CRASH and PC crash programmes. Influence of the transverse, lengthwise and height position of center of gravity was investigated in these programmes with regards to the after-impact behaviour of vehicle. The obtained results were evaluated in the final chapter.

No description available.