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- Post3D Simulation of Representative Volume Element for Use in Multiscale FEM(2004) Grymer, Mikkel; Chalmers tekniska högskola / Institutionen för konstruktionsteknik; Chalmers University of Technology / Department of Structural EngineeringTo closely follow material behaviour in a FE model, a numerical model of the material at a small length-scale can be used instead of material constants. The model of the lower length-scale is run at each integration point in the macroscale model, thereby coupling the models of both length-scales into one large numerical model. This approach is called multi-scale modelling. A three dimensional FE model of the grain structure of a bi-crystalline metal is developed. The model is aimed towards use as mesostructure model used in multi-scale FE computations. Since multi-scale models are computationally very expensive, the entire model was programmed in Fortran to maximize efficiency. The model automatically generates a random 3D grain structure using the Voronoi algorithm. The grain structure is subsequently discretized using a structured, regular grid. Even though the grid geometry is completely decoupled from the grain structure geometry, the model precision is increased by allowing the material properties to vary between integration points within elements, i.e. allowing grain boundaries within an element. The generated model assumes the mesostructure to consist of two grain phases, each phase being linear elastic. Data files for use with the 3D visualization tool Paraview are generated. A parameter study is carried out to study the resulting mesostructure model
- Post3D Structural Analysis of Crack Risk in Hardening Concrete Structures Verification of an Engineering Method(1999) Kjellman, Ola; Chalmers tekniska högskola / Institutionen för byggnadsmekanik; Chalmers University of Technology / Department of Structural Mechanics
- Post3d Surface Scanning - En laserbaserad mätteknik för mätning av yttextur(2002) Choukair, John-Emilè; Hagnert, Mats; Chalmers tekniska högskola / Institutionen för Vatten Miljö Transport; Chalmers University of Technology / Department of Water Environment Transport
- Post3D-analys av stenbågbro med explicit FE-program(1999) Berndtsson, Edward; Berndtsson, Johan; Sandberg, Jonas; Chalmers tekniska högskola / Institutionen för byggnadsmekanik; Chalmers University of Technology / Department of Structural Mechanics
- Post3Dwm: Three-Dimensional User Interfaces Using Fast Constructive Solid Geometry(2001) Elmqvist, Niklas; Chalmers tekniska högskola / Institutionen för datavetenskap; Chalmers University of Technology / Department of Computing ScienceCreating 3D objects for use in applications with three-dimensional user interfaces is a non-trivial and time-consuming task, but could be simplified by the ability to combine 3D primitives into complex shapes using constructive solid geometry (CSG). This thesis presents the design and implementation of an algorithm for fast CSG in the context of the 3Dwm user interface platform. During the development of this algorithm, a number of existing algorithms were evaluated, and one based on binary space partitioning (BSP) trees was selected as the basis for this implementation. Here, polyhedra are represented as solids using augmented BSP trees, and regularized Boolean set operations are performed through incremental construction of the resulting BSP trees. A special tree caching mechanism that stores each subtree of a CSG hierarchy has been implemented to minimize tree evaluation when a part of the hierarchy is modified. The algorithm is efficient, elegant, and integrates seamlessly with the rest of the system without breaking the separation between programming interface and implementation, or the network-transparent nature of the system. In addition to this, provisions have been added to 3Dwm to allow for the creation of mathematical 3D primitives such as spheres, cones, and cylinders, that may be used as part of CSG trees.
- PostA Boundary Element Method for Incremental Non-linear Elasticity(2003) Bertoldi, Katia; Chalmers tekniska högskola / Institutionen för byggnadsmekanik; Chalmers University of Technology / Department of Structural Mechanics
- PostA Case Study of Water Resources Planning in Cyprus - A Test of the MIT Simulation Model(1982) Franzon, Mats; Karlsson, Stefan; Robertsson, Benny; Rogsäter, Bengt; Chalmers tekniska högskola / Institutionen för vattenbyggnad; Chalmers University of Technology / Department of Hydraulics
- PostA digital model of the bicycle network in central Gothenburg - a study considering travel time(2001) Gustavsson, Therese; Valdemarsen, Ann-Kristin; Chalmers tekniska högskola / Institutionen för Vatten Miljö Transport; Chalmers University of Technology / Department of Water Environment Transport
- PostA direct optimisation method for waveguide slot antennas(2000) Forzati, Marco; Chalmers tekniska högskola / Institutionen för elektromagnetik; Chalmers University of Technology / Department of Electromagnetics
- PostA Discontinuous Galerkin method for Structural Dynamics(1998) Ekevid, Torbjörn; Chalmers tekniska högskola / Institutionen för byggnadsmekanik; Chalmers University of Technology / Department of Structural Mechanics
- PostA Machine-assisted Proof of the Subject Reduction Property for a Small Typed Functional Language(1995) Bove, Ana; Chalmers tekniska högskola / Institutionen för datavetenskap; Chalmers University of Technology / Department of Computer Science
- PostA measurement method for damping of drive shaft(2004) Bertilsson, Anders; Chalmers tekniska högskola / Institutionen för teknisk akustik; Chalmers University of Technology / Department of Applied AcousticsSound in our society is beginning to be a health hazard in many places. This leads to legislation and recommendations by public authorities and governments. For a truck the sound pressure level should not exceed 80 dB(A) during a drive-by test set by international standards. This leads to development of the noise for the truck, and different parts get their own allowed component noise level. This thesis will look at one of these parts, i.e. the drive shaft. The goal is to find a test method for controlling the damping in the drive shaft for quality purposes. An additional goal is to see if the method also could secure the target value for the sound pressure level in a drive-by test. Using cardboard tubes inside the drive shafts damps them. In the cases where the drive shafts do not fulfil their target value in a drive-by test, an idea is that the insertion of the cardboard tubes has not worked properly. This calls for a test method for quality purposes and the suggested one is measuring the reverberation time. The manufacturer of the drive shaft wants to make the measurements on the steel tube after the cardboard tubes are mounted, but before the universal joints are welded to the steel tube. To determine the measuring method a lot of measurements are made.The purposes are to decide the excitation tool,the attachment of the detection tool and the measurement position. The measurements on the steel tube should be related to the drive-by measurements. Comparisons have been made between measurements on the steel tube, the drive shaft and the drive shaft mounted in the truck. Simple Finite Element Method models are made to see the mode shapes between a steel tube and a drive shaft,since it is difficult to see this result in the measurements. The result shows that the bending modes change much in frequency while the ringing modes are rather stable. Evaluations are made for the drive-by measurements with differently damped drive shafts. The result showed no clear difference between the tested shafts and the method cannot be used to secure the radiated sound pressure level during a drive-by test. Drive shaft losses have been measured using two methods, the backward integration on the Impulse Response and the half power bandwidth method on the Frequency Response Function. Both these methods can be used to obtain the reverberation time to control the steel tubes to secure the damping for them, if the disadvantages in the methods is known and taken into account. However I recommend the half power bandwidth method since it gives more information of the drive shafts.
- PostA new thermodynamic model for concentrated electrolyte solutions(1987) Liu, Yunda; Chalmers tekniska högskola / Institutionen för värmeteknik och maskinlära; Chalmers University of Technology / Department of Heat and Power Technology
- PostA Parking Choice Model for Göteborg - An Approach on the Implementation of Parking in the SAMPERS- and EMME/2 -system(2000) Johansson, Carl-Henrik; Chalmers tekniska högskola / Institutionen för Vatten Miljö Transport; Chalmers University of Technology / Department of Water Environment Transport
- PostA report on Objective Development of Damper Specification(2018) Adisesh, Ashrith; Agarwal, Rohit; Chalmers tekniska högskola / Extern; Chalmers University of Technology / ExternalDamping of the sprung and un-sprung masses of a vehicle through a suspension damper is crucial to obtain good comfort and handling characteristics. Damper tuning, which is predominantly based on subjective feedback and experience from engineers takes up a large amount of time and resources. Preliminary knowledge of the influence of dampers in different operating regions can provide a good starting point in the damper tuning process. This research thesis aims to develop objective metrics related to the response of simplified vehicle models and could provide information regarding the modifications in the damper specifications to achieve the desired response. Quarter-car models with linear, asymmetric and non-linear damper curves are simulated in the Matlab environment for step and swept sine inputs. The responses are further investigated to identify metrics of interest, by which the behaviour of the vehicle can be understood. For linear damper models, the poles of the system are analyzed and pole placement method is used to understand the behaviour of sprung and un-sprung masses when suspension parameters are varied. For asymmetric dampers, metrics which could help decide the required degree of asymmetricity between compression and rebound damping are presented. Finally, for non-linear dampers, the effect of damping force in different regions of operation is studied. A sensitivity analysis (Design of Experiments) is performed to identify the most influential variables corresponding to these metrics. With these results, the response of the model is studied to obtain the metrics of interest which can be attributed to the behaviour of the vehicle. Comparisons are presented to visualize the effects of different damper specifications by which an initial prediction could be made for the damper specifications. This outcome can potentially enhance the preliminary knowledge of the effects of damper tuning and thereby providing a better starting point for the damper development process.
- PostA Study of Asphalt Concrete Properties with FE Modelling of a Marshall Test(1999) Porras López, Marc; Chalmers tekniska högskola / Institutionen för byggnadsmekanik; Chalmers University of Technology / Department of Structural Mechanics
- PostA study of the design of a wing bracing on a semi submersible drilling unit and the usefulness of RSM in structural design(2002) Elgström, Mattias; Engström, Gustav; Chalmers tekniska högskola / Institutionen för byggnadsmekanik; Chalmers University of Technology / Department of Structural Mechanics
- PostA study of water supply at Nkinga Hospital and three villages in Igunga District, Tanzania.(1992) Anderson, Johan; Wahlström, Ronny; Chalmers tekniska högskola / Institutionen för vattenförsörjnings- och avloppsteknik; Chalmers University of Technology / Department of Sanitary Engineering
- PostA survey of methods for classification of gene expression data using evolutionary algorithms(2006) Wahde, Mattias; Szallasi, Zoltan; Chalmers tekniska högskola / Extern; Chalmers University of Technology / External
- PostA survey of the Swedish security industry and an innovation system analysis of the Swedish security sensor industry(2005) Oltander, Gustav; Perez Vico, Eugenia; Chalmers tekniska högskola / Extern; Chalmers University of Technology / External