Dynamic simulation of collisions of heavy high-speed trucks with concrete barriers

Real vehicle collision experiments on full-scale road safety barriers are important to determine the outcome of a vehicle versus barrier impact accident. However, such experiments require large investment of time and money. Numerical simulation has therefore been imperative as an alternative method for testing concrete barriers. In this research, spring subgrade models were first developed to simulate the ground boundary of concrete barriers. Both heavy trucks and concrete barriers were modeled using finite element methods (FEM) to simulate dynamic collision performances. Comparison of the results generated from computer simulations and on-site full-scale experiments demonstrated that the developed models could be applied to simulate the collision of heavy trucks with concrete barriers to provide the data to design new road safety barriers and analyze existing ones.

Flexible multibody approach in forward dynamic simulation of locomotive strains in human skeleton with flexible lower body bones

A method for bone strain estimation is examined in this article. The flexibility of a single bone in an otherwise rigid human skeleton model has been studied previously by various authors. However, in the previous studies, the effect of the flexibility of multiple bones on the musculoskeletal model behavior was ignored. This study describes a simulation method that can be used to estimate the bone strains at both tibias and femurs of a 65-year old Caucasian male subject. The verification of the method is performed by the comparison of the results with other studies available in literature. The results of the study show good correlation with the results of previous empirical studies. A damping effect of the flexible bones on the model is also studied in this paper.

Simulation of dynamic recrystallization using random grid cellular automata

Computer simulation is a powerful tool to predict microstructure and its evolution in dynamic and post-dynamic recrystallization. CAFE proposed as an appropriate approach by combining finite element (FE) method and cellular automata (CA) for recrystallization simulation. In the current study, a random grid cellular automaton (CA), as micro-scale model, based on finite element (FE), as macro-scale method, has been used to study initial and evolving microstructural features; including nuclei densities, dislocation densities, grain size and grain boundary movement during dynamic recrystallization in a C-Mn steel. An optimized relation has been established between mechanical variables and evolving microstructure features during recrystallization and grain growth. In this model, the microstructure is defined as cells located within grains and grain boundaries while dislocations are randomly dispersed throughout microstructure. Changes of dislocation density during deformation are described considering hardening, recovery and recrystallization. Recrystallization is assumed to initiate near grain boundaries and nucleation rate was considered constant (site-saturated condition). The model produced a mathematical formulation which captured the initial and evolving microstructural entities and linked their effects to measurable macroscopic variables (e.g. stress).

Modelling daylight for preserving identity : simulation of daylight levels for successful intervention in historic buildings

Historical listed buildings have their own unique cultural identity, which is one of the criteria used by decision mechanisms for their statutory protection. The identity of many of these buildings is often related to their tangible features/components, such as period characteristics (geometry, size, colour, form, and shape), materials and construction. Daylight is one of the in/tangible elements that have contributed to the distinctiveness of many historical buildings, yet when constructing preservation schemes of historical buildings, daylight is rarely introduced or considered as one of the components that shape the character of buildings. One of the reasons is the limited number of credible simulation studies that identify such interrelationships. As many of these buildings were originally designed to accommodate different activities to today's requirements, maintaining the quality of daylight that originally contributed to their visual identity can be a very challenging task, especially if the building is to be adapted to accommodate a different activity. In this paper we will discuss the conflict between maintaining the original visual identity of historical buildings and meeting the visual requirements of restored buildings. The paper discusses the visual performance of a traditional bathhouse (Hammam) in the city of Bursa in Turkey. The change in the visual performance of the selected case study will be discussed in terms of daylight conditions. The paper explores the possibility of maintaining the original daylight conditions of renovated historical buildings while meeting the visual requirements of the new use.

Validation of the use of Australian input-output data for building embodied energy simulation

Traditional!y, the simulation of buildings has focused 011 operational energy consumption in an attempt to determine the potential for energy savings. Whilst operational energy of Australian buildings accounts for around 20% of total energy consumption nationally, embodied energy represents 20 to 50 times the annual operational energy of 1110st Australian buildings. Lower values have been shown through a number of studies that have analysed the embodied energy of buildings and their products, however these have now shown to be incomplete in system boundary. Many of these studies have used traditional embodied energy analysis methods, such as process analysis and input-output analysis, Hybrid embodied energy analysis methods have been developed, but these need to be compared and validated. This paper reports on preliminary work on this topic. The findings so far suggest that current best-practice methods are sufficiently accurate for most typical applications, but this is heavily dependant upon data quality and availability.

Modeling and simulation of collisions of heavy trucks with concrete barriers

On-site collision tests of full-scale concrete barriers are an important method to understand what happens to concrete barriers when vehicles collide with them. However, such tests require both time and money, so modeling and simulation of collisions by computer have been developed as an alternative in this research. First, spring subgrade models were developed to formulate the ground boundary of concrete barriers based on previous experiments. Then, the finite element method models were developed for both heavy trucks and concrete barriers to simulate their dynamic collision performances. Comparison of the results generated from computer simulations and on-site experiments demonstrates that the developed models can be applied to simulate the collision of heavy trucks with concrete barriers, to replicate the movement of the truck at the collision, and to investigate the performance of the concrete barriers. The developed research methodology can be widely used to support the design of new concrete barriers and the safety analysis of existing ones.

Simulation of Mg sheet press cell materials

Major characteristics of Magnesium alloy are low density (= 1.8 g/cm³) and excellent recyclability; therefore Mg is considered as one of low environmental loading materials. The low-density materials, such as Mg, are suitable for the transportation system to reduce the emission of Co2, save energy resource and increase the safety for accidents like corrosions. In the place, cellular materials like aluminum foams are also low-density materials and can be controlled the stress-strain relation. Combination of Mg alloy and cellular materials, that is Mg cell, is one of the most excellent materials for transportation system, because of its ultra low density. safeties, and recycle ability. To make the Mg cellular materials. there are some problems to solve. One is how to make them uniformly to supply them as same perfonnance materials. One is how to make them inexpensively. Most of cellular materials are very expensive because of there are many processes or special fabrication system to make them. To solve these problems. we investigated the press cell materials. The press cell material consists sheets pressed as cell shape and wall. Therefore, it is very easy to make cellular materials and control validation of the performance of each foam materials. In this paper, we simulated compression tests of this new type of Mg alloy cellular materials under dynamic loading to investigate the relation between the compression speed and the compression behavior to show the shock absorbing capability of this new foam material. It is very important to understand their mechanical properties relatcd with cell shapes and wall to be applied widely.

Equilibration strategies in molecular dynamics simulation of polyethers

A comparison of the NVT and NVE ensemble simulations of tetraglyme showed that, in terms of energy, temperature and most of the structural features the results were very similar. However, major differences were observed in dynamic properties, ie in the mean square displacement and in the O--O distances. A fast equilibration method suitable for amorphous polymer systems is also detailed. This was accomplished by the reassignment of the velocity distribution to the particles, after the interruption of an NVE simulation.

Many-body dissipative particle dynamics simulation of wetting phenomena

With the development of the simulation of particle dynamics, the traditional dissipative particle dynamics (DPD) method can not satisfy the needs of research in static or dynamic wetting phenomena. However, the Many-body DPD approach extends the ability of the traditional method to simulate the interface between solid and liquid or some other situation. In this paper, we propose a Many-body DPD program to simulate the solid-liquid interface and get satisfactory results.

Fuzzy simulation of pedestrian walking path considering local environmental stimuli

Pedestrian steering activity is a perception-based decision making process that involves interaction with the surrounding environment and insight into environmental stimuli. There are many stimuli within the environment that influence pedestrian wayfinding behaviour during walking activities. However, compelling factors such as individual physical and psychological characteristics and trip intention cause the behaviour become a very fuzzy concept. In this paper pedestrian steering behaviour is modelled using a fuzzy logic approach. The objective of this research is to simulate pedestrian walking paths in indoor public environments during normal and non-panic situations. The proposed algorithm introduces a fuzzy logic framework to predict the impact of perceived attractive and repulsive stimuli, within the pedestrian's field of view, on movement direction. Environmental stimuli are quantified using the social force method. The algorithm is implemented in a simulated area of an office corridor consist of a printer and exit door. Stochastic simulation using the proposed fuzzy algorithm generated realistic walking trajectories, contour map of dynamic change of environmental effects in each step of movement and high flow areas in the corridor.

Dynamic control of skilled and unskilled labour task assignments

Efficient allocation of skilled and non-skilled workers allow a company to improve productivity and usually requires an understanding of personnel capability, operating conditions and resource availability. This paper examines a labour control strategy that optimises labour skill level, utilisation, task execution time and processing error. The proposed controller manages different labour groups in a multiple work cell environment, providing real-time job assignment, as well as guiding and navigation features. These features can be used to enhance the performance of existing MRP-based or Just-In-Time production systems. A discrete event simulation-based manufacturing model has been developed to assess the performance of the labour controller. Experiments conducted for the selected production scenarios have demonstrated a productivity improvement when using the proposed control. A second experiment has shown that when a skilled labour uses the labour controller to guide them through the job, their utilisation also increases. The proposed controller also has potential application in other domains, such as minimising the shopping time at a supermarket

A mathematical model of neuromuscular adaptation to resistance training and its application in a computer simulation of accommodating loads

A large corpus of data obtained by means of empirical study of neuromuscular adaptation is currently of limited use to athletes and their coaches. One of the reasons lies in the unclear direct practical utility of many individual trials. This paper introduces a mathematical model of adaptation to resistance training, which derives its elements from physiological fundamentals on the one side, and empirical findings on the other. The key element of the proposed model is what is here termed the athlete’s capability profile. This is a generalization of length and velocity dependent force production characteristics of individual muscles, to an exercise with arbitrary biomechanics. The capability profile, a two-dimensional function over the capability plane, plays the central role in the proposed model of the training-adaptation feedback loop. Together with a dynamic model of resistance the capability profile is used in the model’s predictive stage when exercise performance is simulated using a numerical approximation of differential equations of motion. Simulation results are used to infer the adaptational stimulus, which manifests itself through a fed back modification of the capability profile. It is shown how empirical evidence of exercise specificity can be formulated mathematically and integrated in this framework. A detailed description of the proposed model is followed by examples of its application—new insights into the effects of accommodating loading for powerlifting are demonstrated. This is followed by a discussion of the limitations of the proposed model and an overview of avenues for future work.

Formulation and simulation of a 3D mechanical model of embryos for microinjection

The understanding of cell manipulation, for example in microinjection, requires an accurate model of the cells. Motivated by this important requirement, a 3D particlebased mechanical model is derived for simulating the deformation of the fish egg membrane and the corresponding cellular forces during microrobotic cell injection. The model is formulated based on the kinematic and dynamic of spring- damper configuration with multi-particle joints considering the visco-elastic fluidic properties. It simulates the indentation force feedback as well as cell visual deformation during microinjection. A preliminary simulation study is conducted with different parameter configurations. The results indicate that the proposed particle-based model is able to provide similar deformation profiles as observed from a real microinjection experiment of the zebrafish embryo published in the literature. As a generic modelling approach is adopted, the proposed model also has the potential in applications with different types of manipulation such as micropipette cell aspiration.