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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Soft Surface Grasping: Radular Opening in Aplysia Californica

Kehl, Catherine Eliza 29 January 2019 (has links)
No description available.
2

A Soft-Body Interconnect For Self-Reconfigurable Modular Robots

Ying, Min 21 April 2014 (has links)
Disaster support and recovery generally involve highly irregular and dangerous environments. Modular robots are a salient solution to support search and rescue efforts but are still limited to do their reliance on a rigid structure design. To enhance flexibility and resilience to damage, a soft-body interconnection mechanism for self-reconfigurable modular robotic systems has been developed. The soft-body interconnection mechanism utilizes elastomeric polymers instead of a rigid body. Hence, it is capable of deforming under extreme loads without damage. This thesis presents the work completed towards the realization of a soft-body interconnection mechanism. The functional requirements of the soft-body mechanism were broken down into two separate modules for extension and capture. An initial simulation demonstrated the inability of using a simulated model made of hypo-elastic materials as a basis for design. Hence, an iterative design process was used to develop an initial extension and capture soft-body mechanisms that conformed to the desired performance parameters. An empirical study which varied multiple structural parameters was then completed with the initial extension and capture soft-body mechanisms as a basis for the modified designs. The data from the study was correlated with measured performance data with resulted in diagrams useful for the optimal design of soft-body extension and capture mechanisms. The use of the diagrams for design was demonstrated in the design and development of a soft-body interconnection mechanism for an in-house designed small hard shell modular robot system.
3

Study on ballistic performance of hybrid soft body armour

Yang, Yanfei January 2016 (has links)
Soft body armour is usually constructed by layering numerous layers of the same fabric. Such a construction, however, may not be the most efficient in providing the required protection due to different ballistic resistant efficiency of each layer. This research aims to optimise the construction of the panels for soft body armour by hybridisation in order to achieve the improvement of ballistic performance and reductions in weight. Twaron woven fabrics with different weave structures and Dyneema uni-directional (UD) laminates were used as components for the hybrid design of panels. Two complementary research approaches were employed in this study, namely the empirical method and the Finite Element (FE) analysis. The first part of this research systematically revealed the different ballistic characteristics of each layer in different positions of an armour panel and the way of energy absorption in the panel. The fabric layers in the front, middle and back of the panel exhibited different extent of transverse deformation and stress distribution. The energy absorption increases from front layer and reaches to the maximum value in the last perforated layer and then decreases gradually in the following back layers. Such pattern of energy absorption was not affected by either the striking velocity or the total number of layers in the panel, but the position, in the thickness, of the peak value in energy absorption was shifted more towards the back of the panel when the striking velocity increases. Such findings contribute to the understanding of different ballistic responses in different positions of an armour panel under ballistic impact. The second part of this research put forward a new hybrid design concept. According to above theoretical understandings of different ballistic characteristics in different positions of an armour panel, the fabric layers in the panel were discretely divided into three groups. In addition to the performance of different components for the panel and the influences of the laying sequence, a procedure for constructing hybrid armour panels has been established. The first group was composed of the first few layers on the striking face. The heavyweight fabrics as heat resistant layers were used in this group to resist the heat generated on the striking face. The second group contained some middle layers close to the last perforated layers. The lightweight fabric was combined in this group due to the higher energy absorption capacity. All back layers were classified into the third group. Dyneema UD laminates were placed in this group to constrain the large transverse deflection of the lightweight fabric and to minimize BFS of the panel. Two hybrid panels were designed and evaluated. In the perforation ballistic tests, the hybrid panel was more likely to stop the projectile compared to Twaron woven panels with the same areal density. In the non-perforation ballistic tests, the hybrid panel exhibited significantly lower BFS and achieved the reductions in weight. Such hybrid design makes best use of different available materials to achieve the improvement of ballistic performance and lightweight of a panel. It has a practical significance for the soft armour panel design.
4

Real-Time Soft Body Physics Engine for Enhanced ConvexPolygon Dynamics

Vickgren, Martin January 2023 (has links)
This thesis covers the development process of implementation, and evaluation of a softbody physics engine for convex polygon objects. The main feature is implementation of adynamic polygon collider that represents a polygons shape correctly, while still being ableto collide with other objects in the simulation. Objects are able to deform both temporarily and permanently using springs with distance constraints. Pressure simulation is alsoimplemented to simulate inflated polygons. The physics bodies does not feature frictionbetween objects, only friction against a static boundary of the simulation. The engine isthen evaluated in order to determine if it can run in real-time which is one of the goals.When it comes to the simulation, Verlet-integration will be used for updating the positions of particles, and every polygon will be built using these particles, and combinedusing certain constraints to make the particles act as one combined object. The main problem that will be solved is the interpenetration solver, which ensures that polygons do notoverlap, and two formulas will be combined to solve this problem. The collision detectionmethod uses line intersections to determine if objects are overlapping, this method endedup being quite expensive for polygons with a lot of vertices. One optimization techniqueis implemented which is axis-aligned bounding boxes around objects which improvedperformance significantly, which also makes the engine more viable for real-time simulations. The physics engine in this report is deterministic using a fixed time-step, dynamictime-step is not tested. The engine also only supports discrete collision detection.
5

Real-time Soft Body Simulation using Extended Position-Based Dynamics and Tetrahedral Deformation

Kamnert, William January 2023 (has links)
Background. Several methods have been used to simulate soft body deformation, such as mass-spring systems and position-based dynamics. This has been done using tetrahedral mesh models for preservation of shape and volume. In real-time applications however, there is a limitation to how high resolution the model can be, creating the need for optimizations. Objectives. To achieve better performance for high resolution models, tetrahedral deformation is used, making it possible for the tetrahedral mesh and triangle mesh to use different resolutions. In combination with this, the GPU is used to execute the simulation in parallel, improving performance further. Methods. For evaluation of performance and accuracy, an implementation was created to simulate soft body deformation using extended position-based dynamics and the Vulkan graphics API, with the option to use tetrahedral deformation. By experimentation, comparisons are made between using different resolutions on the tetrahedral mesh to the full resolution in terms of performance and accuracy. Results. The results show that performance and accuracy are altered when using tetrahedral deformation on lower resolution tetrahedral mesh. The performance is improved based on the decrease in workload, such as with higher base resolution models or multiple soft bodies. The accuracy is however not correlated to the reduction of resolution, but instead dependant on the rest shape of the model used. Conclusions. The implementation created demonstrates a new optimization that can be used to simulate soft body deformation in parallel on the GPU, with a smaller change in accuracy. Improvements exist in areas of usability, features and other optimizations that can be further explored in future research.
6

Poisson Induced Bending Actuator for Soft Robotic Systems

Hasse, Alexander, Mauser, Kristian 08 June 2022 (has links)
This paper deals with a novel active bending soft body that employs metamaterials and combines soft behavior, integrated actuation, low complexity and a high density of producible forces and moments. The presented concept consists of a tube-like structure with tailored, unconventional material properties which enable the generation of a bending deformation and/or moment when circumferential stress and/or strain is induced. Circumferential actuation can be generated by a difference in pressure between the internal and external surface of the tube or, alternatively, by distributed expansion actuators that act radially or tangentially (e.g. shape memory wires). In addition to an analytical model, this paper also presents a design procedure and deals with the implementation of the proposed concept in a functional prototype and its experimental characterization.
7

Continuous Wave Peristaltic Motion in a Robot

Boxerbaum, Alexander Steele 21 May 2012 (has links)
No description available.
8

Kollision deformation med fokus på solida objekt

Habib, Hemn January 2007 (has links)
<p>En realistisk simulation kräver att alla simulerade objekten ska interaktivt och dynamiskt animeras. Delar av objektens kropp ska deformeras och andra delar ska sönderfalla vid en krock med ett annat objekt. De flesta 3d applikationer har som gemensamt vissa tekniker som används vid dynamiska simulationer. Tyvärr så finns det inte en smidig och snabb teknik för att deformera solida objekt vid kollisioner, detta gäller även Maya som jag använde i detta arbete. Detta arbete ska visa en smidig teknik att deformera vissa delar av en komplicerad modell och få andra delar att splittras och spridas i en dynamisk simulation som är både fysiskt rätt och ser visuellt bra ut. Resultatet är en kort animationsfilm som visar teknikerna i praktiken. Enskilda användare av 3Dapplikationer exempelvis studenter kommer ha nytta av arbetets olika delmoment och kan hänvisa till informationen.</p>
9

Análise de desempenho do sistema estrutural de paredes de concreto com ar incorporado / Performance analysis of the structural system of concrete walls with incorporated air

Magalhães, Rafael Machado de 08 September 2016 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A história da construção civil está ligada ao desenvolvimento do homem e têm obtido avanços na área habitacional. Em função desse avanço, o conceito de desempenho de edificações vem sendo estudado, e pode ser entendido como o comportamento em uso das construções ao longo da vida útil. A ABNT NBR 15575:2013 introduziu vários requisitos de desempenho. Esse trabalho tem o objetivo de avaliar requisitos de desempenho em paredes de concreto com ar incorporado. Essa avaliação foi feita através de ensaios de corpo mole e corpo duro, e ensaios de choque térmico. Foram utilizados três tipos de concreto com teores diferentes de aditivo incorporador de ar. Os grupos amostrais foram formados por três protótipos de casas com quatro paredes mais 9 painéis que foram moldados em fôrmas de madeira nas mesmas condições dos protótipos, além da moldagem de 24 cp’s cilíndricos (10 cm x 20 cm), de cada tipo de concreto. Dessa maneira, a variável de entrada foi o teor de aditivo incorporador de ar e as variáveis de saída foram: massa específica, teor de ar e composição real do concreto no estado fresco; e resistência ao impacto de corpo mole e corpo duro, resistência ao choque térmico, módulo de elasticidade, resistência à compressão e massa específica do concreto no estado endurecido. Nos ensaios de corpo mole e corpo duro, os resultados indicaram que o deslocamento instantâneo gerado pelo ensaio de impacto de corpo mole correspondeu a h/13320 (h=2720 mm) e não houve sinais de falhas; os deslocamentos mantiveram uma correlação negativa com o teor de ar e positiva em relação à energia do impacto, representada pela altura de lançamento do saco cilíndrico; a profundidade das mossas foi inferior a 0,085 mm para todas as paredes e protótipos e o SVVE pode ser classificado com nível de desempenho S de acordo com a ABNT NBR 15575:2013. Nos painéis, o teor de ar no concreto influenciou positivamente os resultados da ação do choque térmico; a incorporação de ar reduziu as curvaturas durante a ação do calor e de acordo com a ABNT NBR 15575:2013 o SVVE ensaiado possui nível de desempenho M. / The history of the building is linked to the development of man and have obtained advances in the housing area. Given this progress, the concept of building performance has been studied, and can be understood as the behavior in use of buildings along the lifespan. The ABNT NBR 15575:2013 implemented various performance requirements. This study aims to evaluate performance requirements in concrete walls with incorporated air. This assessment was made by soft body tests, hard body, and thermal shock tests. It has been used three types of concrete with various levels of air additive developer. The sample groups were formed for three prototypes of houses with four walls each, plus 9 panels that were shaped in wooden molds in the same conditions of prototypes, and with the addition of 24 cp’s cylindrical molding's (10 cm x 20 cm), of each type of concrete. Thus, the input variable is the content of air incorporator additive, and the output variables are: specific mass, air content and real concrete composition in the fresh state; impact resistance soft body and hard body, thermal shock resistance, elastic modulus, compressive resistance and the specific mass of the concrete in the hard state. In soft body tests and hard body, the results indicated that the instantaneous displacement generated by the soft body impact test corresponding to h/13320 (h = 2720 mm) and no failures signals; displacements maintained a negative correlation with air content and positive regarding the impact energy, represented by the release height of the cylindrical bag; the depth of the dents is less than 0.085 mm for the walls and prototypes and SVVE can be rated performance level S according to ABNT NBR 15575:2013. The panels, the air content in the concrete positively influenced the results of the thermal shock action; the incorporation of air reduced the curvatures during the action of heat and according to NBR 15575:2013 the SVVE tested has performance level M. / Dissertação (Mestrado)
10

Kollision deformation med fokus på solida objekt

Habib, Hemn January 2007 (has links)
En realistisk simulation kräver att alla simulerade objekten ska interaktivt och dynamiskt animeras. Delar av objektens kropp ska deformeras och andra delar ska sönderfalla vid en krock med ett annat objekt. De flesta 3d applikationer har som gemensamt vissa tekniker som används vid dynamiska simulationer. Tyvärr så finns det inte en smidig och snabb teknik för att deformera solida objekt vid kollisioner, detta gäller även Maya som jag använde i detta arbete. Detta arbete ska visa en smidig teknik att deformera vissa delar av en komplicerad modell och få andra delar att splittras och spridas i en dynamisk simulation som är både fysiskt rätt och ser visuellt bra ut. Resultatet är en kort animationsfilm som visar teknikerna i praktiken. Enskilda användare av 3Dapplikationer exempelvis studenter kommer ha nytta av arbetets olika delmoment och kan hänvisa till informationen.

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