Abstract

The vehicle design environment from a crashworthiness and safety perspective has become increasingly complex in recent years. New legal requirements imposed by the European Union (EU) and the United States National Highway Traffic Safety Administration (NHTSA) have created a design space of great complexity with many parameters that must be balanced to arrive at an overall design that performs adequately in all of these situations. The customer introduces further complexity through the addition of Consumer requirements in many markets that will influence a purchasing decision. In order to design to all of these conditions, an approach of using physical testing solely has problems associated with it. Due to the prohibitive nature of vehicle prototypes and limited availability during Engineering Development, other tools such a Computer Aided Engineering (CAE) have become popular. This paper will discuss the design space and modeling methods for creating an occupant crashworthiness model suitable for studying vehicle structural and restraint system effects. The results of parametric studies showing injury trends for a given vehicle/restraint system combination will be presented. Copyright © 2001 Society of Automotive Engineers, Inc.

Abstract

Nowadays analytical models of seismic isolators can fairly reproduce the force response of such devices, when implemented in a large variety of structural systems, such as buildings and bridges. Consequently, realistic hysteretic rules are available for the definition of the dynamic system for Non-Linear Time History Analyses, and earthquake simulations of the considered isolated structural systems can be computed. Such models are generally defined, according to mean values of mechanical properties of isolation devices, even though a certain variability has been experimentally assessed: precisely, statistical analyses of the outcomes of test database have outlined that the main response parameters of isolators should be considered as random variables, rather than as deterministic values. On the other hand, in the common practice both design and assessment procedures are mainly based on deterministic approaches, and bound analyses are ruled in just few standard codes. The present endeavor presents a wide parametric study on a case study structure, in order to assess the variability of the main response parameters, by accounting for random mechanical properties of isolation devices. Precisely, a combination of Lead Rubber Bearings and Flat Slider devices have been considered, and the spatial layout of isolators has been defined, according to a given performance point. The structural response of the case study building has been computed through Non-Linear Time History Analyses, by extracting 10'000 individual values of mechanical properties of devices. Presented results are related to the mean response of a spectrum-compatible set of natural records, in terms of displacement and force of both superstructure and isolation system.

Abstract

Fruit packaging is highly impactful in temperature and humidity distribution for post-harvest fresh fruit cooling and conservation. It is also the most flexible part on fruit production and should be able to increase shelf-life by deterring adverse conditions. However, packaging thermal performance during cold storage where it is displayed to the internal airflow is influenced by the size and position of vent-holes. In this study airflow inside the fruit box and fruits thermal behaviour are evaluated in order to determine differences between three prototype package models. Models differ from each other by the holes' configuration and size. Furthermore, models' performance is compared to a commercially available box of similar dimensions. Experimental tests were carried out in three stacked boxes, equipped with temperature and humidity sensors, and placed inside a refrigeration chamber with forced air cooling. Packaging box CFD models of each prototype wall were developed to predict the airflow and heat transfer during storage in a refrigeration chamber. Models predictions were validated by experiments results. According with simulation results, all prototypes have better thermal performance than the commercial model. However, significant performance differences between prototype walls were found. Fewer, larger and strategically distributed vent-holes allow a better result in terms of temperature homogeneity inside the box and significant reduction in fruit cooling times.

Abstract

Operators of V-bending process have sometimes been injured because of broken piece of a die. To prevent this accident, a structure of the die that is tough to break is required. According to the previous study, introducing a hole in the V-bending die reduced stresses at the bottom of V-groove. Therefore, parametric study of a hole in a structure is necessary to find an appropriate design of the structure. However, parametric study of a structure with a hole using conventional FEM has difficulty in remeshing. Using coupling-matrix-free iterative s-version FEM, a mesh of the whole analysis domain and a mesh in the vicinity of the hole can be created separately as a global mesh and a local mesh, respectively. In this study, we proposed a parametric analysis system to analyze the die with a hole for V-bending process, and we evaluated the results in terms of fracture mechanics.