Understanding wear conditions during hot stamping

Wear and galling are significant issues during production hot stamping processes. This paper uses thermo-mechanical finite element analysis to study the contact pressure, sliding distance and temperature conditions that occur at the wearing interface during hot stamping. Several hot stamping processes are studied, representing the numerous methods that are used in industry to form a typical hat-shaped channel component. These process include crash forming (without blankholder), stamping with a blank holder with an applied blank holder pressure, and stamping with a clearance blank holder (i.e. with spacer blocks). This paper identifies the distinct contact pressure and temperature conditions that occur for each of these forming methods. The regions of the most severe contact conditions are notably different for each of the forming methods. The work from this paper will form the basis for the development of suitable temperature dependent wear models and low cost wear tests for industrial hot stamping applications.

Crash investigation of side intrusion beam during high and low pressure tube hydroforming

Advanced high strength steels (AHSS), in particular, are an attractive group materials, offering higher strength for improved energy absorption and the opportunity to reduce weight through the use of thinner gauges. High pressure tube hydroforming (HPTH) has been used to produce safety components for these steels, but it is expensive. Low pressure tube hydroforming (LPTH) is a lower cost alternative to form the safety components in the car. The side intrusion beam is the second most critical part after front rail in the car structure for passenger safety during crash. The forming as well as crash behaviour of a square side intrusion beam from both processes was investigated using numerical simulation. This paper investigated the interaction between the forming and crash response of these materials in order to evaluate their potential for use in vehicle design for crashworthiness. The energy absorption characteristics of the different tubes were calculated and the results from the numerical analyses compared for both hydroforming process.

Formability and forming of advanced steels

The thesis identified how advanced high strength steels perform compared to conventional steels in terms of weight reduction and crash performance for automotive bodies. The novel production method of low pressure tube hydroforming was applied to form these advanced steels to reduce the press tonnage and fluid pressure compared to the conventional high pressure process. In addition analytical models were developed to predict the force and pressure in the low pressure process.

A first step towards a simple in-line shape compensation routine for the roll forming of high strength steel

The roll forming process is increasingly used in the automotive industry for the manufacture of structural and crash components from Ultra High Strength Steel (UHSS). Due to the high strength of UHSS (<1GPa) even small and commonly observed material property variations from coil to coil can result in significant changes in material yield and through that affect the final shape of the roll formed component. This requires the re-adjustment of tooling to compensate for shape defects and maintain part geometry resulting in costly downtimes of equipment. This paper presents a first step towards an in-line shape compensation method that based on the monitoring of roll load and torque allows for the estimation of shape defects and the subsequent re-adjustment of tooling for compensation. For this the effect of material property variation on common shape defects observed in the roll forming process as well as measurable process parameters such as roll load and torque needs to be understood. The effect of yield strength and material hardening on roll load and torque as well as longitudinal bow is investigated via experimental trials and numerical analysis. A regression analysis combined with Analysis of Variance (ANOVA) techniques is employed to establish the relationships between the process and material parameters and to determine their percentage influence on longitudinal bow, roll load and torque. The study will show that the level of longitudinal bow, one of the major shape defects observed in roll forming, can be estimated by variations in roll load and torque.

Flexible roll forming of an automotive component with variable depth

Roll forming is a cost and energy efficient process for the manufacture of Ultra High Strength Steel (UHSS) structural and crash components in the automotive industry. The conventional roll forming process is limited to component having constant cross-section, while the recently deveoped Flexible Roll Forming (FRF) process allows the production of components in which the section varies over the length of the aprt; this permits optimization in terms of strength and weight. There has been an uptake in FRF in the heavy vehicle industry for the production of long and high strength structural parts, but passenger car bodies are more complex and generally parts require variations in width and also in depth. The widespread application of FRF in the automotive industy therefore requires the forming of components that have intricate variations in profile depth over the length of the part.
This work is a first comprehensive study of the FRF of high strength structural components with variable depth. For this, the FRF of an automotive bumper section is analyzed numerically using the commercial software package COPRA® FEA RF. A detailed analysis of the distribution and history of plastic strain in longitudinal, transcerse and thickness directions is performed and related to the shape defects observed in the proecss. The analysis shows that when forming variable depth components, zones of compressive longitudinal strain exist that lead to wrinkling defects. These can be reduced by applying additional flange contact during the operation. In general the current work suggests that the FRF of high strength components with variable depth is possible and can compete with other forming methods currently used in the automotive industry.

Bwembya Chikolwa interviewed by Nicole Lindsay for Herald Sun 20th August 2009, Property trusts hit hard by US crash,

Listed Australian property companies wrote off more than $8.5 billlion from their ill-fated US investment adventures during this reporting season.

An investigation of differences in crash characteristics between males and females involved in a fatigue-related crash or close call event

There is consensus among community and road safety agencies that driver fatigue is a major road safety issue and it is well known that excessive fatigue is linked with an increased risk of a motor vehicle crash. Previous research has implicated a wide variety of factors involved in fatigue-related crashes and the effects of these various factors in regard to crash risk can be interpreted as causal (i.e. alcohol and/or drugs may induce fatigue states) or additive (e.g. where a lack of sleep is combined with alcohol). As such, the purpose of this investigation was to examine self-report data to determine whether there are any differences in the prevalence, crash characteristics, and travel patterns of males and females involved in a fatigue-related crash or close call event. Such research is important to understand how fatigue related incidents occur within the typical driving patterns of men and women and it provides a starting point in order to explore if males and females experience and understand the risk of diving when tired in the same way. A representative sample of (N = 1,600) residents living in the Australian Capital Territory (ACT) and New South Wales (NSW), Australia, were surveyed regarding their experience of fatigue and their involvement in fatigue-related crashes and close call incidents. Results revealed that over 35% of participants reported having had a close call or crash due to driving when tired in the five years prior to the study being conducted. In addition, the results obtained revealed a number of interesting characteristics that provide preliminary evidence that gender differences do exist when examining the prevalence, crash characteristics, and travel patterns of males and females involved in a fatigue-related crash or close call event. It is argued that the results obtained can provide particularly useful information for the refinement and further development of appropriate countermeasures that better target this complex issue.

The effectiveness of using a simple ARIA based geographical classification to identify road crash patterns in rural and urban areas of Queensland

Research has noted a ‘pronounced pattern of increase with increasing remoteness' of death rates in road crashes. However, crash characteristics by remoteness are not commonly or consistently reported, with definitions of rural and urban often relying on proxy representations such as prevailing speed limit. The current paper seeks to evaluate the efficacy of the Accessibility / Remoteness Index of Australia (ARIA+) to identifying trends in road crashes. ARIA+ does not rely on road-specific measures and uses distances to populated centres to attribute a score to an area, which can in turn be grouped into 5 classifications of increasing remoteness. The current paper uses applications of these classifications at the broad level of Australian Bureau of Statistics' Statistical Local Areas, thus avoiding precise crash locating or dedicated mapping software. Analyses used Queensland road crash database details for all 31,346 crashes resulting in a fatality or hospitalisation occurring between 1st July, 2001 and 30th June 2006 inclusive. Results showed that this simplified application of ARIA+ aligned with previous definitions such as speed limit, while also providing further delineation. Differences in crash contributing factors were noted with increasing remoteness such as a greater representation of alcohol and ‘excessive speed for circumstances.' Other factors such as the predominance of younger drivers in crashes differed little by remoteness classification. The results are discussed in terms of the utility of remoteness as a graduated rather than binary (rural/urban) construct and the potential for combining ARIA crash data with census and hospital datasets.

Crash Risk Assessment with Cooperative Systems

Crash risk is the statistical probability of a crash. Its assessment can be performed through ex post statistical analysis or in real-time with on-vehicle systems. These systems can be cooperative. Cooperative Vehicle-Infrastructure Systems (CVIS) are a developing research avenue in the automotive industry worldwide. This paper provides a survey of existing CVIS systems and methods to assess crash risk with them. It describes the advantages of cooperative systems versus non-cooperative systems. A sample of cooperative crash risk assessment systems is analysed to extract vulnerabilities according to three criteria: market penetration, over-reliance on GPS and broadcasting issues. It shows that cooperative risk assessment systems are still in their infancy and requires further development to provide their full benefits to road users.

Applying data mining to assess crash risk on curves

The wide range of contributing factors and circumstances surrounding crashes on road curves suggest that no single intervention can prevent these crashes. This paper presents a novel methodology, based on data mining techniques, to identify contributing factors and the relationship between them. It identifies contributing factors that influence the risk of a crash. Incident records, described using free text, from a large insurance company were analysed with rough set theory. Rough set theory was used to discover dependencies among data, and reasons using the vague, uncertain and imprecise information that characterised the insurance dataset. The results show that male drivers, who are between 50 and 59 years old, driving during evening peak hours are involved with a collision, had a lowest crash risk. Drivers between 25 and 29 years old, driving from around midnight to 6 am and in a new car has the highest risk. The analysis of the most significant contributing factors on curves suggests that drivers with driving experience of 25 to 42 years, who are driving a new vehicle have the highest crash cost risk, characterised by the vehicle running off the road and hitting a tree. This research complements existing statistically based tools approach to analyse road crashes. Our data mining approach is supported with proven theory and will allow road safety practitioners to effectively understand the dependencies between contributing factors and the crash type with the view to designing tailored countermeasures.

Mining patterns and factors contributing to crash severity on road curves

Road curves are an important feature of road infrastructure and many serious crashes occur on road curves. In Queensland, the number of fatalities is twice as many on curves as that on straight roads. Therefore, there is a need to reduce drivers’ exposure to crash risk on road curves. Road crashes in Australia and in the Organisation for Economic Co-operation and Development(OECD) have plateaued in the last five years (2004 to 2008) and the road safety community is desperately seeking innovative interventions to reduce the number of crashes. However, designing an innovative and effective intervention may prove to be difficult as it relies on providing theoretical foundation, coherence, understanding, and structure to both the design and validation of the efficiency of the new intervention. Researchers from multiple disciplines have developed various models to determine the contributing factors for crashes on road curves with a view towards reducing the crash rate. However, most of the existing methods are based on statistical analysis of contributing factors described in government crash reports. In order to further explore the contributing factors related to crashes on road curves, this thesis designs a novel method to analyse and validate these contributing factors. The use of crash claim reports from an insurance company is proposed for analysis using data mining techniques. To the best of our knowledge, this is the first attempt to use data mining techniques to analyse crashes on road curves. Text mining technique is employed as the reports consist of thousands of textual descriptions and hence, text mining is able to identify the contributing factors. Besides identifying the contributing factors, limited studies to date have investigated the relationships between these factors, especially for crashes on road curves. Thus, this study proposed the use of the rough set analysis technique to determine these relationships. The results from this analysis are used to assess the effect of these contributing factors on crash severity. The findings obtained through the use of data mining techniques presented in this thesis, have been found to be consistent with existing identified contributing factors. Furthermore, this thesis has identified new contributing factors towards crashes and the relationships between them. A significant pattern related with crash severity is the time of the day where severe road crashes occur more frequently in the evening or night time. Tree collision is another common pattern where crashes that occur in the morning and involves hitting a tree are likely to have a higher crash severity. Another factor that influences crash severity is the age of the driver. Most age groups face a high crash severity except for drivers between 60 and 100 years old, who have the lowest crash severity. The significant relationship identified between contributing factors consists of the time of the crash, the manufactured year of the vehicle, the age of the driver and hitting a tree. Having identified new contributing factors and relationships, a validation process is carried out using a traffic simulator in order to determine their accuracy. The validation process indicates that the results are accurate. This demonstrates that data mining techniques are a powerful tool in road safety research, and can be usefully applied within the Intelligent Transport System (ITS) domain. The research presented in this thesis provides an insight into the complexity of crashes on road curves. The findings of this research have important implications for both practitioners and academics. For road safety practitioners, the results from this research illustrate practical benefits for the design of interventions for road curves that will potentially help in decreasing related injuries and fatalities. For academics, this research opens up a new research methodology to assess crash severity, related to road crashes on curves.

An adaptive local meshfree updated Lagrangian approach for large deformation analysis of metal forming

The large deformation analysis is one of major challenges in numerical modelling and simulation of metal forming. Because no mesh is used, the meshfree methods show good potential for the large deformation analysis. In this paper, a local meshfree formulation, based on the local weak-forms and the updated Lagrangian (UL) approach, is developed for the large deformation analysis. To fully employ the advantages of meshfree methods, a simple and effective adaptive technique is proposed, and this procedure is much easier than the re-meshing in FEM. Numerical examples of large deformation analysis are presented to demonstrate the effectiveness of the newly developed nonlinear meshfree approach. It has been found that the developed meshfree technique provides a superior performance to the conventional FEM in dealing with large deformation problems for metal forming.