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.

Validated model and study of a rammed earth wall building

A 2100 m² (GFA) two-storey rammed earth building was built on the Thurgoona campus of Charles Sturt University in 1999. The building is novel both in the use of materials and equipment for heating and cooling. The climate at Wodonga can be characterised as hot and dry, so the challenge of providing comfortable working conditions with minimal energy consumption is considerable. This paper describes a thermal model of one of the second-storey offices on the west-end of the building. The simulation software, TRNSYS, has been used to predict office temperatures and comparisons are made between these and measurements made over a typical week in summer. Reasonable agreement has been achieved under most conditions. The model has been used to investigate key building parameters and strategies, including night flushing, to improve the thermal comfort in the office.

Towards a digital representation of physical phenomena to assess comfort in future environments

This paper presents the concept and a test implementation of a digital representation of the physical world designed to assess comfort quality in
future environments. An integrated set of physical phenomena is modeled three-dimensionally to investigate the dynamic behavior of design objects
holistically.

The formulation supports the integration of computational simulation in the performance-based design process. It employs the principles of
geometrical and physical selfcontainedness to avoid that complex geometrical and physical circumstances have to be specified at design time. The concepts of congeneric cells and congeneric conjunctions are
introduced to simulate various physical phenomena simultaneously with a uniformly structured set of equations.

The concept, the prototype implementation and selected test cases are presented. Although it was not possible to implement all features and model parts completely, the research and the discussion of its achievements make valuable contributions towards more effective integration of computational simulation in the performance-based design process.

Propagation characteristics of lamb waves in stringer-stiffened panels

Stringer-stiffened plate-like structure is a typical engineering structure and its structural integrity is critical. A guided Lamb wave-based damage identification scheme and an online structural health monitoring (SHM) system with an integrated PZT-sensor network were developed. In the previous studies, the specimens were relatively simple. In this paper, the above mentioned method was extended to the stiffened plate-like structure—a flat plate reinforced by stringer. FE dynamic simulation was applied to investigate the Lamb wave propagation characteristics due to the existence of stringer with the consideration of its material and geometric configurations.

3D hydrodynamic analysis of a biomimetic robot fish

This paper presents a three-dimensional (3D) computational fluid dynamic simulation of a biomimetic robot fish. Fluent and user-defined function (UDF) is used to define the movement of the robot fish and the Dynamic Mesh is used to mimic the fish swimming in water. Hydrodynamic analysis is done in this paper too. The aim of this study is to get comparative data about hydrodynamic properties of those guidelines to improve the design, remote control and flexibility of the underwater robot fish.

The influence of various seat design parameters: a computational analysis

Nowadays, low back pain becomes a common healthcare problem. Poor or unsuitable seat design is related to the discomfort and other healthcare problems of users. The aim of this study is to investigate the influence of seat design variables on the compressive loadings of lumbar joints. A basis that includes a musculoskeletal human body model and a chair model has been developed using LifeMOD Biomechanics Modeller. Inverse and forward dynamic simulations have been performed for various seat design parameters. The results show that the inclination of backrest and seat pan may or may not decrease the compressive spinal joint forces, depending on other conditions. The medium-level height and depth of seat pan and the medium-level and high-level height of backrest are found to cause the minimum compressive loads on lumbar joints. This work contributes to a better understanding of sitting biomechanics and provides some useful guidelines for seat design.

The effect of green roofs on pedestrian level air temperature

Man made alterations have resulted in higher air temperatures in cities, compared to their surrounding rural areas. There are many attempts to modify the urban design elements to ameliorate urban heat island effect. One among them is the concept of green roofs. There is a potential to incorporate vegetation to the large roof area of the buildings. Several studies investigated the effect of micro and macro scale implementation of green roofs. Most of these studies examined the impact of green roofs on the air temperature variation at the roof level, whereas studies are lacking on the effect of green roof at the pedestrian level. Therefore, this study aims to explore the impact of green roofs on the air temperature at pedestrian level, in the central business district (CBD), using Melbourne as a case study. A generic layout of Melbourne's CBD is modelled using ENVI-met 3.1 BETA 4. A number of different scenarios with different green roof coverages and building heights are examined. It was found that green roofs did not have significant impact on the temperatures at pedestrian level.

Thermal simulation studies of a low energy university building in Australia

A key criterion by which any building will be judged when its environmental impact is assessed is its thermal performance. This paper describes the simulation of an office module in a three-storey university building in south eastern Australia. The module, located at the north-west corner of the top floor of the building, was chosen because it is likely to have the highest cooling load - a primary concern of energy conscious designers of commercial buildings for most parts of Australia.

In the paper, the initial key assumptions are stated, together with a description of a "reference" or base case, against which improvements in thermal performance were measured. The simulation process identified the major influences on thermal performance. This enabled changes in materials and construction, as well as basic design concepts to be evaluated. Features incorporated into the base case such as a metal roof and glazed walkway were found to have adverse influence on energy consumption, and were consequently rejected in preference for an improved design which included a hypocaust slab system on the roof of the office module. The final design was predicted to reduce the annual energy consumption for heating and cooling by 72% and 76% respectively.

La performance thermique est l'un des critegraveres cleacutes de l'eacutevaluation environnementale de tout bacirctiment. Cet article deacutecrit la simulation d'un module de bureau appartenant agrave un immeuble de trois eacutetages d'une universiteacute du sud-est de l'Australie. Ce module, situeacute agrave l'angle nord-ouest de l'eacutetage supeacuterieur du bacirctiment a eacuteteacute choisi car c'eacutetait lui qui, vraisemblablement, avait la charge de refroidissement la plus eacuteleveacutee, ce qui est une preacuteoccupation majeure des concepteurs conscients des problegravemes d'eacutenergie des bacirctiments commerciaux dans la plus grande partie du pays. Le processus de simulation a fait apparaicirctre trois influences principales sur la performance thermique par rapport agrave un cas de base. Cela a permis d'eacutevaluer les modifications apporteacutees aux mateacuteriaux et agrave la construction ainsi qu'aux avant-projets. Les caracteacuteristiques inteacutegreacutees dans le cas de base comme le toit meacutetallique et la passerelle vitreacutee avaient une influence neacutefaste sur la consommation d'eacutenergie et ont donc eacuteteacute rejeteacutees au beacuteneacutefice d'un concept ameacutelioreacute qui comprenait une dalle de type hypocauste sur le toit du module de bureau. Le concept final devrait reacuteduire la consommation annuelle d'eacutenergie pour le chauffage et le refroidissement de 72 % et 76 % respectivement, ce qui donne une ideacutee de la valeur ajouteacutee au processus de production agrave partir de proceacutedures avanceacutees de modeacutelisation et de simulation.

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.

Waste production simulation for building deconstruction projects

The recently erected concept of building deconstruction has significantly promoted building components and materials reuse and recycling where building is carefully dismantled into reusable parts. Current research and practices of building deconstruction mainly focus on issues of process before and during the deconstruction such as hazardous material detection, deconstruction design and deconstruction technology. The issues after the deconstruction project are rarely considered. Waste reuse and recycling are enabled through deconstruction yet not practically achieved, and especially the demands of waste building components and materials are hard to appear and match the actual waste production in a building deconstruction project. To deal with this awkward situation, the waste production needs to be conducted in a demand-oriented way. It needs to be thoughtfully planned and scheduled prior to the physical deconstruction as an essential portion of deconstruction project planning and scheduling. Furthermore, the relationship between waste production and structural characteristics of the building creates a serious consideration affecting a deconstruction plan. As a result, a waste production simulation will facilitate waste reuse and recycling in a deconstruction project. It serves as a crucial section of deconstruction planning and design. This research aims to describe the concept of waste production simulation and investigate various management and technical aspects of waste production simulation for building deconstruction projects.

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).

Evaluation of thermal and visual comfort in offices considering realistic input data and user behaviour in building simulation

Thermal and visual comfort play a very important role regarding the satisfaction of occupants with their working environments. The most effective method to achieve thermal comfort in offices is to reduce cooling loads in order to avoid additional energy-consuming devices for cooling. Building simulation software can be a helpful tool for optimisation, and typically standard values for the influencing parameters are used in order to ensure compliance to norms and regulations.

In practice many of those parameters turn out to be different compared to the simulation assumptions and the reasons may be the chosen room or building related properties as well as the user behaviour influenced by the task and the corporate culture of the company.

This paper investigates exemplary for the climate of Hamburg, Germany and a naturally ventilated typical office room, the optimisation potential of the building- and user-related parameters for thermal comfort, daylighting and view when using realistic input data for building simulation. The study has been conducted with the EnergyPlus based simulation software “Primero-Komfort” [1].