Presentation Abstracts

Solid Particle Erosion is one of the major problems in pump industry, since operation in erosive environment could cause performance alterations of pumps with consequent increased maintenance and running costs, mainly due to the lower efficiency. The research work aimed to study the erosion phenomenon in vertical multistage submersible pumps and develop new coatings as means to prolong their operating life through the reduction of the erosion rate. The mechanical properties of various coatings were examined using nanoindentations, impact tests, 3D-surface topography and Finite Element Analysis. Following a computational performance analysis of a pump stage using CFD software, the experimental results were used to calculate the erosion factor k which has been introduced in the Finnie Erosion Model to computationally determine the erosion rate of the pump stage.

The main criteria for the implementation of CFD methods for the accurate prediction of multiphase, multi - component and reactive flows are presented. These flows are commonly reported in a broad range of industrial applications. The development of reliable computational models can provide robust solutions, leading to design and process optimization. An insight on the available approaches for the numerical modelling of multiphase flows is initially addressed. Examples of the implementation of both Euler - Euler, Euler - Lagrange methodologies for the simulation of standard gas - solid, gas - liquid flows are depicted. Additionally, challenges on the modelling of turbulent, multiphase, multi-component flows of reacting mixtures are issued, focusing on the system's thermo-kinetic behaviour. Alternative ways of implementing chemical kinetic schemes in commercial CFD environments are addressed, by demonstrating simulation results for indicative test cases of hydrocarbon oxidation in laboratory scale reactors.

The speaker will provide a overview of the extensive set of capabilities for Implicit Mechanics in LS-DYNA. Including

• Static and Dynamic Time Simulation
• Inertia Relief
• Vibration and Buckling Analysis
• Constraint and Attachment Modes
• Linearized Parts

These capabilities will be demonstrated with examples from aerospace, automotive and metal forming applications.

This overview presentation outlines how Computer Aided Engineering (CAE) Technologies support the design process of innovative new products. As demands on manufacturing companies are mounting, margins for error are decreasing in globally ever more competitive markets. Building a virtual prototype on a computer and testing and fully understanding its behaviour before even touching real materials on the shop floor remove risk from the devopment process and help to get it right the first time.

An efficient methodology is presented for predicting dynamic response and fatigue life of large scale mechanical models, subjected to random excitation. The equations of motion of the class of models examined are set up by applying the finite element method. Very often, this results to an excessive number of degrees of freedom. In addition, these models may possess nonlinear characteristics. The methodology developed is based on a combination of techniques leading to a fast and accurate determination of the dynamic response with a method related to an efficient prediction of fatigue life. Specifically, the first step of this methodology involves the application of an appropriate coordinate transformation, causing a drastic reduction in the original number of degrees of freedom. Then, another step in the same direction is the application of a systematic numerical method leading to direct determination of steady state response of nonlinear models subjected to periodic excitation. The approach chosen provides a solid foundation for the subsequent application of a rainflow stress cycle counting method, leading to prediction of fatigue failure. The computational accuracy and effectiveness of the methodology developed is illustrated by a quite involved example model, representing a city bus subjected to road excitation. Typical results are presented for both the response and the fatigue life by considering excitation arising from selected urban road profiles with known statistical properties. Special attention is paid on assessing the effect of the nonlinearity, by considering road profiles with different quality. Moreover, the applicability of classical spectral methods employed in linear formulations, is also investigated. In this way, a critical comparison is performed on results referring to the expected fatigue lifetime, obtained by applying methods in both the frequency and the time domain.

The development of an innovative "Fishbone" fluid level sensor will be presented starting from the first idea, over simulation up to the materialization of functioning samples.

The sensor is based on an innovative concept of measuring the echo of torsion pulses, travelling along a stack of wing-shaped units on a metal sheet and then reflected from the fluid surface. A simplified transient dynamical fluid-structure interaction has been proposed and successfully applied for dimensioning and optimizing the sensor.

In a second presentation, an additional overview of a broad range of CAE-activities at the Fuel Supply Business Unit of the Continental Corporation will be given.

We shall present a general overview of various CAE activities in our Business Unit, all applied to our products - assemblies in motor vehicle fuel tanks, consisting of electrically driven and jet pumps, level sensors, valves, pressure regulators, electronic control units, filter housings, flanges etc.

A rich variety of different analysis fields is being regularly applied: Static and dynamic mechanical, crash, time durability, electromagnetic, acoustic, computational fluid dynamics and a number of coupled physical effects.

In particular, we shall give a short insight into our analysts' daily life, being often involved in all aspects of product creation - from the first idea, through development up to the ripe phase leading to the start of production. We shall also highlight the decentralized structure, functioning as a network of analysts spread at six company sites at three different continents.

Since 1970s the finite element method has initiated to be applied in order to predict the strains and stresses induced at several positions of the human skeleton under several pathological conditions. Among several orthopaedic cases, particular attention has been paid to date to the hip, knee, tibia, foot, elbow, shoulder and the spine. The 'Biomechanics Unit' at the NTUA has an experience of seventeen years in Computational Biomechanics, having initiated with dental biomechanics (orthodontic movements, dental implants) and then moved to most of the aforementioned orthopaedic applications. This presentation focuses in the human spine, where particular ANSYS models of several vertebrae (developed during the last eight years) will be reviewed. In general, while one decade ago the geometrical data of vertebrae were taken using mechanical or/and laser digitizers, to date it is accepted that this task is better performed using Computed Tomography (CT) scans, on which patient-specific CAD models can be easily developed. Then, typical interfaces such as IGES or STL are used to transfer the geometrical data from the CAD to the ANSYS environment.

Typical models of lumbar vertebras (e.g. L1), thoracic vertebras (e.g. T12) as well as a certified model of the entire lumbar spine including nonlinear ligaments (useful for the analysis of back-pain) will be presented. Particular attention will be paid on female vertebras affected by the osteoporosis decease, where in-house software has been developed to assign local bone density and relevant Young's modulus. Finally, numerical results of bone remodeling (i.e., the variation of bone density as a response to the mechanical loading) obtained by an in-house code written in the command language APDL will be presented.

As a conclusion, it was found that ANSYS offers a fertile environment for the rapid development of patient-specific FEM models. In other words, these models are useful for close to clinical applications, as they require about five hours per vertebra. In the near future, it is anticipated that specific add-on ANSYS applications will be developed to assist medical doctors in the evaluation of the mechanical integrity of the vertebras or/and the entire spine.

Several personal transportation options are available such as Conventional Gasoline Vehicles, Hybrid Electric Vehicles, Plug-in Hybrid Electric Vehicles and Electric Vehicles. An overview of recent advances in infrastructure and new "charging concepts" for electric vehicles will be presented. In order to answer the question, if alternative vehicles make sense, an integration process of several multi-disciplinary simulation models with modeFRONTIER will be presented.