Dissertationen zum Thema „Multi-Material optimization“
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Ajayi, Oluwanifemi O. (Oluwanifemi Oluwadara). „Topology optimization with manufacturable multi-material primitives“. Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/123215.
Der volle Inhalt der QuelleCataloged from PDF version of thesis.
Includes bibliographical references (pages 32-33).
Topology optimization is a field extending to the built environment. Traditionally, optimization focuses mainly on monolithic structures but recently, developments have been made toward determining algorithms for multi-material optimization. A preexisting algorithm is modified to broaden the type of design possible with the method. The algorithm uses a three-phase design problem, a void phase and two other materials, and implements Heaviside Projection Method (HPM) and Rational Approximation of Material Properties (RAMP) method and employs the Method of Moving Asymptotes (MMA) as the gradient based optimizer. Three distinct object projection shapes are proposed, a horizontal, a vertical and a diagonal. The horizontal shaped inclusion enables designs such as, longitudinal reinforced concrete beam design of variable length bars. The vertical shaped inclusion enables designs of columns. The diagonal shaped inclusion allows for design of rebar within more slanted sections of optimized topology. The proposed algorithm is tested on two examples, the cantilever beam and the MBB beam, showing that it works as expected.
by Oluwanifemi O. Ajayi.
M. Eng.
M.Eng. Massachusetts Institute of Technology, Department of Civil and Environmental Engineering
Park, Jaejong. „Advanced Topology Optimization Techniques for Engineering and Biomedical Problems“. The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1534347400733419.
Der volle Inhalt der QuelleVenugopal, Vysakh. „Design of Multi-Material Lattice Structures with Tailorable Material Properties using Density-Based Topology Optimization“. University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1553252070840125.
Der volle Inhalt der QuelleStern, Brenda G. „Minimizing embodied carbon in multi-material structural optimization of planar trusses“. Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119324.
Der volle Inhalt der QuelleCataloged from PDF version of thesis.
Includes bibliographical references (pages 55-56).
In the built environment, there is a growing emphasis on sustainable, energy efficient design that reduces carbon emissions. However, until recently, most efforts have focused only on reducing operational carbon [1]. As a result, the carbon embodied in construction materials, especially in a building's structural system, is becoming a larger contributor to the total carbon impacts of a building. Material type and quantity are important in determining the extent of this contribution because both will affect the amount of carbon emitted from the material production. For example, two common materials for truss structures are timber and steel. While timber's embodied carbon coefficient (kg[subscript CO2e]/kg[subscript material]) and density are lower than that of steel, its much lower strength means that it may not always result in the least-emitting structural design. As a result, the choice of the more sustainable material for any given member is dependent on factors such as the truss span or shape. Multi-material structures offer a solution to create efficient structures with a lower environmental impact. In this thesis, an embodied carbon optimization investigates truss structures of various spans and studies how multi-material and single-material designs compare. This research introduces a new approach for multi-material designs for the optimization of embodied carbon and demonstrates the advantages of using structural optimization and multi-material designs for sustainability. Keywords.: Optimization, embodied carbon, sustainable structures, truss structures
by Brenda G. Stern.
M. Eng.
Brister, Kenneth Eugene. „MULTI-OBJECTIVE DESIGN OPTIMIZATION USING METAMODELING TECHNIQUES AND A DAMAGE MATERIAL MODEL“. MSSTATE, 2007. http://sun.library.msstate.edu/ETD-db/theses/available/etd-07032007-121410/.
Der volle Inhalt der QuelleBrister, Kenneth Eugene. „Multi-objective design optimization using metamodelling techniques and a damage material model“. Master's thesis, Mississippi State : Mississippi State University, 2007. http://library.msstate.edu/etd/show.asp?etd=etd-07032007-121410.
Der volle Inhalt der Quelleda, Silva de Siqueira Renan [Verfasser]. „Design and Optimization Method for Manufacturable Multi-material Components / Renan da Silva de Siqueira“. Garbsen : TEWISS - Technik und Wissen GmbH, 2019. http://d-nb.info/1204212929/34.
Der volle Inhalt der QuelleSchmidt, Bastian [Verfasser], Michael [Akademischer Betreuer] Stingl und Jaroslav [Akademischer Betreuer] Haslinger. „Topology Preserving Multi-Layer Shape and Material Optimization / Bastian Schmidt. Gutachter: Michael Stingl ; Jaroslav Haslinger“. Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2014. http://d-nb.info/1075476747/34.
Der volle Inhalt der QuellePfirsching, Marion [Verfasser]. „A multi-scale model for material flow problems based on a non-local conservation law: simulation and optimization / Marion Pfirsching“. München : Verlag Dr. Hut, 2018. http://d-nb.info/1162768134/34.
Der volle Inhalt der QuelleMeisel, Nicholas Alexander. „Design for Additive Manufacturing Considerations for Self-Actuating Compliant Mechanisms Created via Multi-Material PolyJet 3D Printing“. Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/54033.
Der volle Inhalt der QuellePh. D.
Sordelet, Tyler Christopher. „Design and optimization of a multi-particle accelerator beam transport and delivery system for material irradiation in nuclear and fusion science“. Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/76574.
Der volle Inhalt der Quelle"December 2011." Cataloged from PDF version of thesis.
Includes bibliographical references (p. 129-131).
A beam delivery and transport system were designed for the use in MIT Materials Test Facility (M2TF). The purpose of this beam delivery system was to design a 36 MeV Proton Cyclotron for DPA accumulation and a 100 MeV Helium Cyclotron for irradiation failure and volumetric helium accumulation simulation. The purpose of the beam transport system was to incorporate the two cyclotrons into the beam transport system and transport their beams to the target chamber, the location of the target sample. The cyclotrons were designed using Opera-3D and Acfields. The beam transport system was designed using TRANSPORT. The shielding analysis for the entire facility was designed using SolidWorks and calculated with MCNP/X The design specification of M2TF with respect to beam energy, current density, and control were achieved based on these design tools and previously developed analytic methods. The design process for the cyclotrons resulted in a 4.3T lsochronous Proton Cyclotron and 3.9T Isochronous Helium Cyclotron. A beam transport system connected the cyclotrons to the target chamber with three doublet quadrupoles and one dipole bending magnet The shielding calculation proved the total effect dose rate in rem/year for the final design facility was safe for operational workers.
by Tyler Christopher Sordelet.
S.M.
PIZZOLATO, ALBERTO. „Topology optimization for energy problems“. Doctoral thesis, Politecnico di Torino, 2018. http://hdl.handle.net/11583/2710567.
Der volle Inhalt der QuellePai, Vibha. „Evaluation of Changes between the Material and Resource Category of LEED v4.0 and v3.0 as it Pertains to New Construction and Major Renovations“. University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin151203942639125.
Der volle Inhalt der QuelleLee, Jin Woo. „Multi-level Decoupled Optimization of Wind Turbine Structures Using Coefficients of Approximating Functions as Design Variables“. University of Toledo / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1501003238831086.
Der volle Inhalt der QuelleFENG, KELI. „THREE ESSAYS ON PRODUCTION AND INVENTORY MANAGEMENT“. University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1122442476.
Der volle Inhalt der QuelleCherrière, Théodore. „Élaboration de méthodes et d'outils logiciels pour l'optimisation topologique magnéto-mécanique de machines électriques tournantes“. Electronic Thesis or Diss., université Paris-Saclay, 2023. http://www.theses.fr/2023UPAST159.
Der volle Inhalt der QuelleIn the context of energy transition and the electrification of applications, improving the performance of electromagnetic actuators inevitably involves dimensioning optimization processes. Such methodologies have already been implemented but focus mainly on previously parameterized geometries, which limits the space of possibilities. This thesis aims to develop an efficient topological optimization methodology capable of optimizing the distribution of materials (iron, air, conductors, magnets) required to generate a synchronous machine in its entirety without parameterizing its geometry. To this end, a multi-material density topological optimization methodology has been developed. Its application to optimizing a three-phase stator highlights the importance of penalization, filtering, and control processes in the optimization algorithm. The procedure is then extended to the design of an entire machine: although efficient, the best structures obtained include flux barriers with no mechanical strength. After incorporating rotor stiffness constraints, the method produces high-performance, related structures in a reasonable computation time, demonstrating the relevance of this type of approach to the design of electromagnetic actuators. Eventually, integrating all the physics involved in specifications right from the preliminary phases will save time and money in designing innovative electrical machines
Vuoluterä, Fredrik, und Oliver Carlén. „Analysis of material flow and simulation-based optimization of transportation system : The combination of simulation and Lean to evaluate and design a transportation system“. Thesis, Högskolan i Skövde, Institutionen för ingenjörsvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-15974.
Der volle Inhalt der QuelleCarbonari, Ronny Calixto. „Projeto de multi-atuadores piezelétricos homogêneos e gradados utilizando o método de otimização topológica“. Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/3/3152/tde-04102016-093909/.
Der volle Inhalt der QuelleMicrotools offer significant promise in a wide range of applications such as cell manipulation, microsurgery, nanotechnology processes, and many other fields. The microtools considered in this doctoral thesis essentially consist of a multi-flexible structure actuated by two or more piezoceramic devices that when each piezoceramic is actuated, it generates an output displacement and force at a specified point of the domain and direction. The multi-flexible structure acts as a mechanical transformer by amplifying and changing the direction of the piezoceramic output displacements. Thus, the development of microtools requires the design of actuated flexible structures that can perform complex movements. The development of these microtools is still in the beginning and it can be strongly enhanced by using design tools. In addition, when multiple piezoceramic devices are involved, coupling effects in their movements become critical, especially the appearance of undesired movements, which makes the design task very complex. One way to avoid such undesirable effects is the use of a systematic design method, such as topology optimization, with appropriate formulation of the optimization problem. The topology optimization method implemented is based on the CAMD (Continuous Approximation of Material Distribution) approach where fictitious densities are interpolated at each finite element, providing a continuum material distribution in the domain. The corresponding sensitivity analysis is presented using the adjoint method. Three formulations are considered. The first formulation, called Piezoelectric Multi-Actuators (PMAs), keeps fixed piezoceramic positions in the design domain and only the flexible structure is designed by distributing some non-piezoelectric material (Aluminum, for example). $XY$ Piezoelectric Nanopositioner are manufactured and experimentally analyzed to validate the results of the topology optimization obtained using this formulation. Experimental analyses are conducted using laser interferometry to measure displacement, while considering a quasi-static excitation. However, this first formulation imposes a constraint to the position of piezoelectric material in the optimization problem limiting the optimality of the solution. Thus, the second formulation presented, called LOMPs, allows the simultaneous distribution of non-piezoelectric and piezoelectric material in the design domain, to achieve certain specified actuation movements. The optimization problem is posed as the simultaneous search for an optimal topology of a flexible structure as well as the optimal position of piezoceramics in the design domain and optimal rotation angle of piezoceramic material axes that maximize output displacements or output forces at a specified point of the domain and direction. When the distribution of a non-piezoelectric conductor material and a piezoceramic material is considered in the design domain, the electrode positions are not known ``a priori\'\'. To circumvent this problem, an electric field is applied as electrical excitation. Finally, the concept of functionally graded materials (FGM) is applied to PMAs design. FGMs are special materials that possess continuously graded properties without interfaces which can increase lifetime of piezoelectric devices. Thus, a third formulation is implemented to find the optimum gradation and polarization sign variation of piezoceramic FGMs, while simultaneously optimizing the multi-flexible structural configuration. This formulation is extended to design bimorph type FGM actuators. For all developed formulations, a multi-objective function is defined that controls the stiffness and flexibility, minimizing the coupling movement of each actuated movement. The present examples are limited to two-dimensional models because most part of the applications for such micro-tools are planar devices.
Zhou, Zhen. „Study on optimization of hazardous material transportation via lane reservation“. Thesis, Evry-Val d'Essonne, 2014. http://www.theses.fr/2014EVRY0041/document.
Der volle Inhalt der QuelleHazardous material transportation is well-known for its high potential risk. An accident may cause very serious economic damage and negative impacts on the public health and the environment over the long term. Optimization for hazardous material transportation is an important issue. For the first time in the literature, this thesis introduces the lane reservation strategy into the hazardous material transportation problem. The goal is to obtain a best compromise between the impact on normal traffic due to lane reservation and the transportation risk.In this thesis, we focus on two novel problems: hazardous material transportation problem via lane reservation in networks with time-invariant and time-dependent risk, called LRPTIR and LRPTDR, respectively. For these problems, multi-objective integer programming and multi-objective mixed integer programming models are formulated, respectively. For the LRPTIR, we first develop an ε-constraint and fuzzy-logic based method to obtain Pareto optimal solutions and a preferred solution. Then a cut-and-solve and cutting plane combined method is proposed to reduce the computational time. For the LRPTDR, an improved cut-and-solve based ε-constraint method is proposed, in which a new technique of generating piercing cuts is developed and a partial integral relaxation strategy is applied. The performance of the proposed algorithms is evaluated by randomly generated instances. Computational results demonstrate that for the considered problems, the cut-and-solve method outperforms software package CPLEX
Chibane, Hicham. „Contribution à l'optimisation multi-objectif des paramètres de coupe en usinage et apport de l 'analyse vibratoire : application aux matériaux métalliques et composites“. Thesis, Tours, 2013. http://www.theses.fr/2013TOUR4053/document.
Der volle Inhalt der QuelleManufacturing processes of mechanical parts by removal of material (turning, milling, drilling ...) have extensive use in aeronautic and automobile industry. The components obtained using these methods must satisfy geometric properties, metallurgical and quality characteristics. To meet these requirements, several experimental tests based on the selection of cutting conditions are often necessary before manufacturing. Currently, these empirical methods based on the experience of manufacturers and users of cutting tools (charts, diagrams with experimental findings, ...) are often very lengthy and costly. However, the high cost of a trial limits the number of experiments, so to have a deserted component with an acceptable cost is a difficult task. The importance of cutting conditions monitored by limitations is related to the type of material to be machined, since it determines the behavior of the machining
Roccamena, Letizia. „Optimization of an innovative thermal energy storage technology at low temperatures when coupled to multi-source energy architectures“. Thesis, Lyon, 2017. http://www.theses.fr/2017LYSET010/document.
Der volle Inhalt der QuelleOne of the most promising technics used in building applications for energy efficiency purposes is the thermal energy storage (TES). Despite the thorough research on TES techniques of the last years, the release to market of cost effective technologies is quite recent. The aim of this study is to optimize the energetic behavior of an innovative TES technology consisting on a water/PCM exchanger that is part of the multi-energy production and storage systems of HIKARI, a positive energy district located in Lyon and consisting of three buildings. In order to optimize this innovative technic, a numerical model reproducing the functioning of the reference system was created. In order to make a numerical validation a second numerical model was developed using a different software based on a different numerical method and, once the in situ data obtained from the reference system monitoring, a first experimental validation was obtained. Subsequently, an innovative experimental prototype reproducing the behavior of the reference PCM-Water heat exchanger has been realized, in order to validate and calibrate the numerical model and carry out a large amount of operating scenarios. Once the model numerically and experimentally validated, the optimization of the HIKARI’s cold storage system technology has been obtained using Genetic Algorithms (GAs) finding the best values to allocate to four characteristics of the cold storage system, in order to minimize two predefined objective functions linked to its functioning. This work was supported by the French Agency for Environment and Energy Management (ADEME) and it was part of the project “Optimization of innovative energy storage technologies when coupled to multi-sources energy architectures”, in cooperation with Bouygues immobilier and Manaslu – CMDL
Ali, Muzdalifa. „Using dynamic programming and unsupervised learning to optimize material flow in assembly line supermarket : A case study of Volvo Powertrain at Skövde“. Thesis, Högskolan i Skövde, Institutionen för informationsteknologi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-17597.
Der volle Inhalt der QuelleMotaweh, Tammam. „Modélisation et validation expérimentale de nouvelles structures SOA large bande et de techniques d'élargissement de la bande passante optique“. Thesis, Brest, 2014. http://www.theses.fr/2014BRES0117/document.
Der volle Inhalt der QuelleSOA-based optical amplification became crucial for increasing optical system capacity and to benefit from the broad bandwidth of optical fibers. In this work we present both theoretical and experimental studies for a new broadband SOA developed by Alcatel Thales III-V lab in the framework of AROME and UltraWIDE ANR projects.We developed firstly a semi-phenomenological model for both the material gain and the gain coefficient of a multi-quantum well -based SOA structure with a reduced set of parameters. This material gain model has been integrated in an existing SOA model and proved its performance in reproducing steady state behavior of this new broadband SOA (gain and noise figure) for a wide range of wavelengths, input powers and bias currents. Thanks to this model, we studied the influence of the SOA geometrical structure on the optical bandwidth for a given target gain, by varying length, number of electrodes and bias current. We showed that two-electrode SOA structures do not provide any improvement of the bandwidth compared to the one-electrode case. However, the two-electrode structure allows the optimization of both the SOA saturation power and the noise figure, without sacrificing neither the maximum gain nor the optical bandwidth. We have also shown that for this kind of component, an increase in the injected optical power could be compensated by an increase in the supply current to maintain a wide optical bandwidth.We have also investigated two techniques to widen the optical bandwidth of our broadband SOA. The first one is based on a modification of the SOA structure by introducing a selective reflection filter (ESOA). Its experimental implementation allowed the amplification of an 8-CWDM-channel comb in a bandwidth (defined at -1 dB) of 140 nm. The second one, based on a hybrid Raman-SOA amplifier, provided an optical bandwidth (defined at -1 dB) of 89 nm with a gain of 17 dB. With this last technique, we were able to achieve a 5-CWDM-channel comb transmission up to 10 Gb/s over 100 km
Beckstein, Pascal. „Methodenentwicklung zur Simulation von Strömungen mit freier Oberfläche unter dem Einfluss elektromagnetischer Wechselfelder“. Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-232474.
Der volle Inhalt der QuelleSolis, Ocampo Jennifer. „Multi material topology optimization with hybrid cellular automata“. Thesis, 2017. https://doi.org/10.7912/C2P06X.
Der volle Inhalt der QuelleTopology Optimization is a technique that allows for the obtaining structures which maximize the use of the material. This is done by intelligently deciding the binary distribution of solid material and void, in a discretized given space. Several researchers have provided methods to tackle binary topology optimization. New ef- forts are focused on extending the application for multi-phase optimizations. At the industrial level, several components designed are made up of more than one material to reduce weight and production costs. The objective of this work is to implement the algorithm of Hybrid Cellular Automaton for multi-material topology optimiza- tion. The commonly used interpolation rule SIMP, which allows to relate the design variables to the mechanical properties of the material, is replaced by ordered SIMP interpolation function. The multiple volume constraints are applied sequentially, starting with the most elastic material. When a constraint is satisfied, the elements assigned to this material remain passive by a defined number of iterations to promote the convergence of the solution. Examples are shown for static and dynamic loads. The work demonstrates the versatility of algorithms based on control systems to solve problems of multiple phases and transient response fields.
Habibian, Anahita. „Multi-material topology optimization of structures with discontinuities using Peridynamics“. Thesis, 2020. http://hdl.handle.net/1828/12528.
Der volle Inhalt der QuelleGraduate
Chuang, Yueh-Lung, und 莊岳龍. „Finding the System Parameters of Multi-objective Optimization for Material Handling in an FMS“. Thesis, 2007. http://ndltd.ncl.edu.tw/handle/63081549954826285045.
Der volle Inhalt der Quelle國立雲林科技大學
工業工程與管理研究所碩士班
95
The material handling system ( MHS ) is the most complex component of an advanced flexible manufacturing system ( FMS ). It utilizes various functions and resource to regulate the part movement from one work-center to another. The material handling action occupies most of the production action, therefore the practice and theory of MHS possess decisive influence in the production management and operating cost. We apply simulation software to build up an flexible manufacturing system and adopt the response surface methodology ( RSM ). It can help us to realize the full potential design, schedule and control in AGV system. In this research, we consider two different objectives: Average throughput and Average AGV utility rate. System parameters of AGV amount, AGV speed, AGV dispatching rule, batch and machine dispatching rule were considered. We combine average throughput with average AGV utility rate to from a single desirability function to find optimal parameters of system.
Barroca, Bruno Miguel do Carmo. „Optimal shape and topology of multi-material microstructures in min-max stress design problems“. Master's thesis, 2019. http://hdl.handle.net/10362/94886.
Der volle Inhalt der Quelle„Phase field model for optimization of multi-material structural topology in two and three dimensions“. Thesis, 2005. http://library.cuhk.edu.hk/record=b6074149.
Der volle Inhalt der QuelleThe fourth-order nonlinear parabolic C-H equations with elasticity are solved by a powerful nonlinear implicit mutigrid algorithm. To validate its correctness and efficiency, I first use it for the quadternary C-H equations without elasticity and get good results. To my best knowledge, it is the first simulation for such C-H models composed of more than three phases both in 2D and 3D.
The Optimization of Structural Topology (OST) is a breakthrough in product design because it can optimize size, shape and topology synchronously under different physical constraints. It has promising applications in industry ranging from automobile and aerospace engineering to micro electromechanical system.
Then this dissertation introduces a gradient flow in the norm of H-1 for the problem of multi-material structural topology optimization in 2/3D with a generalized Cahn-Hilliard (C-H) model with elasticity. Unlike the traditional C-H model applied to spinodal separation which only has bulk energy and interface energy, the generalized model couples the macroscopic elastic energy (mean compliance) into the total free energy. As a result, the grain morphology is not random islands or zigzag web-like objects but regular truss or bar structure. Although disturbed by elastic energy, the C-H system still keeps its two most important properties: mass conservation and energy dissipation. Therefore, it is unnecessary to compute the Lagrange multipliers for the volume constraints and make extra effort to minimize the mean compliance (elastic energy) for the optimization of structural topology. On the other hand, when pure phases separate from disordered original state, their boundaries will merge and split resulting in natural and flexible topology variation. Such aforementioned properties make the C-H model especially suitable for the problem of optimization of multi-material structural topology.
This dissertation also extends the famous Solid Isotropic Material with Penalization (SIMP) model from 2D to 3D for topology optimization of the structure with single material. A short 177-line Matlab code including 3D Finite Element Method (FEM), filter technique, Optimality Criteria (OC) algorithm and bisection method is listed in appendix A for clear understanding of this model in 3D.
This dissertation first substitutes the nonlinear diffusion method for filter process in the optimization of structural topology. Filtering has been a major technique used in a homogenization-based method for topology optimization of structures. It plays a key role in regularizing the basic problem into a well-behaved setting. But it has a drawback of smoothing effect around the boundary of material domain. A diffusion technique is presented here as a variational approach to the regularization of the topology optimization problem. A nonlinear or anisotropic diffusion process not only leads to a suitable problem regularization but also exhibits strong "edge"-preserving characteristics. Thus, it shows that the use of the nonlinear diffusions brings desirable effects of boundary preservation and even enhancement of lower-dimensional features such as flow-like structures. The proposed diffusion techniques have a close relationship with the diffusion methods and the phase-field methods of the fields of materials and digital image processing.
Zhou Shiwei.
"December 2005."
Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6713.
Thesis (Ph.D.)--Chinese University of Hong Kong, 2005.
Includes bibliographical references (p. 140-151).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstracts in English and Chinese.
School code: 1307.
Machado, José Joaquim da Mota. „Impact strength optimization with cohesive zone elements of multi-material bonded structures used in the automotive industry“. Doctoral thesis, 2019. https://hdl.handle.net/10216/123591.
Der volle Inhalt der QuelleLIU, WEI-ZHI, und 劉韋志. „Study on Process Parameters Optimization of multi-material Molding of a Tooth Brush by Mold Flow Analysis“. Thesis, 2017. http://ndltd.ncl.edu.tw/handle/48828859339190543124.
Der volle Inhalt der Quelle國立高雄應用科技大學
機械工程系
105
In this study, mold flow analysis and Taguchi experimental methods were both applied to investigate the injection molding parameter’s effects on the shrinking property of a multi-material toothbrush. The material used for the skin layer, injected first, of the toothbrush is PP, while TPE is for the core layer. Both PP and TPE are nonpolar materials, so good bonding between the two can be expected. A rotation tool system was built and used to mold the toothbrush before this study take place. To shorten the cycle time, the cooling times for the first and second shots must be the same in this continuous manufacturing process. First, we found the influence of each parameter on shrinkage by Moldex3D simulation analysis, and used Taguchi experimental method to find the optimization parameter combinations. The amount of shrinkage was improved to 3.78 mm from original 8.5 mm. Because the core TPE layer was covered by the PP skin layer, and TPE was injected after PP, taking the heat out from the TPE core has to go through PP skin layer, the cooling efficiency is low. To further improve the shrinkage problem, we tried to inject the TPE core layer first in the simulation, so the TPE core can receive better cooling. The results indicated that the amount of shrinkage can be improved to 3.65 mm from 8.50 mm with 60 seconds cooling.
Machado, José Joaquim da Mota. „Impact strength optimization with cohesive zone elements of multi-material bonded structures used in the automotive industry“. Tese, 2019. https://hdl.handle.net/10216/123591.
Der volle Inhalt der QuellePinto, Cristiana Sofia Santos. „Core back moulding, adhesion optimization in the joining area“. Master's thesis, 2020. http://hdl.handle.net/1822/69578.
Der volle Inhalt der QuelleWhen industries need to make components with two or more materials using just one mould and one machine, they use multi-material injection moulding techniques. One of these techniques is the core back moulding that allows the subsequent injection of two different materials without opening the mould, commonly used for parts with simple geometry, normally a rigid part involved with an elastomer. These moulds are very complex in its structure, therefore the design of the mould, its construction and assembly need to be carefully done to avoid part defects. Moreover, multi-material injection moulding may be a challenge regarding the adhesion between materials, being dependent on materials compatibility, materials rheological characteristics and injection moulding conditions used. The present dissertation addresses the development of a core back mould for the production of a complex bi-material part for the automotive industry and the study of the processing conditions that best promote the adhesion between the materials used. For that different tools where used such as Solidworks for the mould design, and DOE for the design of experiments. The mould development went through several steps such as the design of the injection, cooling, ejection and gas trap systems. Then the mould components were machined and assembled. Finally, the mould was tested and the parts were analysed. A study about the adhesion of the materials in this type of moulds and how the processing conditions influence the interface quality was realised. To simplify that study, a Design of Experiments was performed. This method is used to reduce the number of tests, assuring the reliability of the results. Finally, to analyse the adhesion of the parts, tensile tests were performed. It was concluded that the mould had a good performance. Parts were successfully made and the strength of the joints evaluate. It was concluded that the adhesion between materials was more efficient in the part extremities comparing with the middle zones. These results are attributed to the location of the gate and also the complex geometry of the part. Furthermore, the processing conditions influence the strength of the joint region. The set of values that would optimise PP/EPDM joints are the injection temperature of the second material of 200ºC, the mould temperature of 40ºC and the injection pressure of 80bar.
Quando as indústrias necessitam de fazer componentes com dois ou mais materiais utilizando apenas um molde e uma máquina, utilizam técnicas de moldação por injeção multi-material. Uma destas técnicas é a moldação core back que permite a subsequente injeção de dois materiais diferentes sem abertura do molde, normalmente utilizada para peças com geometria simples, como uma peça rígida envolvida com um elastómero. Estes moldes são muito complexos, pelo que a conceção do molde, a sua construção e montagem precisam de ser realizadas cuidadosamente para evitar defeitos nas peças. Além disso, a moldação multi-material pode ser um desafio no que respeita à adesão entre os materiais, dependendo da compatibilidade dos materiais, características reológicas e condições de processamento. A presente dissertação aborda o desenvolvimento de um molde core back para a produção de uma peça bi-material para a indústria automóvel e o estudo das condições de processamento que melhor promovem a adesão entre os materiais utilizados. Para isso são utilizadas diferentes ferramentas, tais como Solidworks para o desenho do molde, e DOE. O desenvolvimento do molde passou por várias etapas, tais como a conceção dos sistemas de injeção, arrefecimento, ejeção e escape de gás. Em seguida, os componentes do molde foram maquinados e montados. Finalmente, o molde foi testado e as peças foram analisadas. Foi realizado um estudo sobre a adesão dos materiais neste tipo de moldes e como as condições de processamento influenciam a qualidade da interface. Para simplificar esse estudo, foi realizado um Design of Experiments. Este método é utilizado para reduzir o número de ensaios, assegurando a fiabilidade dos resultados. Finalmente, para analisar a adesão das peças, foram realizados ensaios de tração. Concluiu-se que o molde tinha um bom desempenho. As peças foram produzidas com sucesso e a resistência da zona de união foi avaliada. Concluiu-se que a adesão entre os materiais era mais eficiente nas extremidades das peças, em comparação com as zonas médias. Estes resultados devem-se à localização do ponto de injeção e também à complexa geometria da peça. Além disso, as condições de processamento influenciam a resistência da zona de união. O conjunto de valores que otimizariam a adesão da peça PP/EPDM são a temperatura de injeção do segundo material de 200ºC, a temperatura do molde de 40ºC e a pressão de injeção de 80bar.
Gokhale, Vaibhav V. „Design of a helmet with an advanced layered composite for energy dissipation using a multi-material compliant mechanism synthesis“. Thesis, 2016. http://hdl.handle.net/1805/10910.
Der volle Inhalt der QuelleTraumatic Brain Injuries (TBI) are one of the most apprehensive issues today. In recent years a lot of research has been done for reducing the risk of TBI, but no concrete solution exists yet. Helmets are one of the protective devices that are used to prevent human beings from mild TBI. For many years some kind of foam has been used in helmets for energy absorption. But, in recent years non-traditional solutions other than foam are being explored by different groups. Focus of this thesis is to develop a completely new concept of energy absorption for helmet liner by diverting the impact forces in radial directions normal to the direction of impact. This work presents a new design of an advanced layered composite (ALC) for energy dissipation through action of a 3D array of compliant mechanisms. The ALC works by diverting incoming forces in multiple radial directions and also has design provisions for reducing rotational forces. Design of compliant mechanism is optimized using multi-material topology optimization algorithm considering rigid and flexible material phases together with void. The design proposed here needs to be manufactured using the advanced polyjet printing additive manufacturing process. A general and parametric design procedure is explained which can be used to produce variants of the designs for different impact conditions and different applications. Performance of the designed ALC is examined through a benchmark example in which a comparison is made between the ALC and the traditional liner foam. An impact test is carried out in this benchmark example using dynamic Finite Element Analysis in LS DYNA. The comparison parameters under consideration are gradualness of energy absorption and peak linear force transmitted from the ALC to the body in contact with it. The design in this article is done particularly for the use in sports helmets. However, the ALC may find applications in other energy absorbing structures such as vehicle crashworthy components and protective gears. The ultimate goal of this research is to provide a novel design of energy absorbing structure which reduces the risk of head injury when the helmet is worn.
Liu, Kai. „Concurrent topology optimization of structures and materials“. Thesis, 2013. http://hdl.handle.net/1805/3755.
Der volle Inhalt der QuelleTopology optimization allows designers to obtain lightweight structures considering the binary distribution of a solid material. The introduction of cellular material models in topology optimization allows designers to achieve significant weight reductions in structural applications. However, the traditional topology optimization method is challenged by the use of cellular materials. Furthermore, increased material savings and performance can be achieved if the material and the structure topologies are concurrently designed. Hence, multi-scale topology optimization methodologies are introduced to fulfill this goal. The objective of this investigation is to discuss and compare the design methodologies to obtaining optimal macro-scale structures and the corresponding optimal meso-scale material designs in continuum design domains. These approaches make use of homogenization theory to establish communication bridges between both material and structural scales. The periodicity constraint makes such cellular materials manufacturable while relaxing the periodicity constraint to achieve major improvements of structural performance. Penalization methods are used to obtain binary solutions in both scales. The proposed methodologies are demonstrated in the design of stiff structure and compliant mechanism synthesis. The multiscale results are compared with the traditional structural-level designs in the context of Pareto solutions, demonstrating benefits of ultra-lightweight configurations. Errors involved in the mult-scale topology optimization procedure are also discussed. Errors are mainly classified as mesh refinement errors and homogenization errors. Comparisons between the multi-level designs and uni-level designs of solid structures, structures using periodic cellular materials and non-periodic cellular materials are provided. Error quantifications also indicate the superiority of using non-periodic cellular materials rather than periodic cellular materials.
Beckstein, Pascal. „Methodenentwicklung zur Simulation von Strömungen mit freier Oberfläche unter dem Einfluss elektromagnetischer Wechselfelder“. Doctoral thesis, 2017. https://tud.qucosa.de/id/qucosa%3A30749.
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