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Conceptual suspension modelling in automated vehicle dynamics simulations
2003 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

In modern vehicle design, dynamic simulation is a tool for optimal design of complex engineering systems. When using complete car models in the simulations the number of design variables tend to increase to a level which is hard to handle. In this master thesis the possibility to implement the methodology of Target Cascading in modern dynamics simulations for design optimisation is examined. Although this methodology is used the focus lie on creating assemblies using the CSM-module from Adams/Car and making the process automated. The dynamics simulation software used is ADAMS/Car which is a specialised simulation environment for vehicle design and testing. In order to implement the Target Cascading process within ADAMS/Car a bi- level hierarchical partition was created with a simplified full vehicle assembly at the top level and ordinary front and rear suspension assemblies at the system (lower) level. The simplified full-vehicle assembly is created with the major parts from the Volvo V70 but with the suspension and steering changed to the Conceptual Suspension Model (CSM) steer and suspension assemblies from ADAMS/Car. The CSM suspension and steer module uses assemblies with very few parts to reduce complexity. The CSM- suspension characteristics are defined by toe, chamber, and wheel-rate curves and a compliance matrix. These curves, called suspension curves, provide the location and orientation of the wheel centre for any given wheel height and loading condition. By changing values in tables and single curve coefficients in the suspension curves and running several driving case simulations, targets set at the top level can be calculated. When optimal design targets have been found at the top level the Target Cascading methodology focuses at the system level. At the system level the front and rear suspension are used to generate new suspension curves. To obtain suspension curves with different characteristics, hardpoints and bushing properties are changed prior to simulation start. The suspension curves from the system level are then compared to the one (ones) at the top level which gave the optimal results. The aim is to minimise the difference between these curves. In order to make the process faster and more easy to use it was automated using scripts written in Python, Unix-Bourne shell programming language and Adams macro language. The simulations are also generated and distributed by the object-oriented mediator database AMOS II from Uppsala University. This Master Thesis describes a part of the area of Target Cascading and vehicle dynamics simulation. The results show that it is possible to implement Target Cascading in dynamic simulations. By using the CSM-models a more complex assembly and its many variables may be reduced to a more easily handled model which may be used to examine the handling of a vehicle in an early stage of a design project.

Place, publisher, year, edition, pages
2003.
Keyword [en]
Technology, Conceptual suspension modelling, CSM, Adams/Car, Target, Cascading, Dynamics simulations
Keyword [sv]
Teknik
Identifiers
URN: urn:nbn:se:ltu:diva-48718ISRN: LTU-EX--03/036--SELocal ID: 62585c9e-5c69-4abb-b47d-4664323f86deOAI: oai:DiVA.org:ltu-48718DiVA: diva2:1022062
Subject / course
Student thesis, at least 30 credits
Educational program
Mechanical Engineering, master's level
Examiners
Note
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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