This thesis has been carried out together with Kalmar Global’s Innovation Center and covers a concept study about weight reduction of the telescopic boom of the Reachstacker DRG 450.The reason for this weight reduction is to ease Kalmar’s transition from fossil fueled to electric driven vehicles since less weight reduces energy consumption and leaves more room for batteries. The main focus of the study is to test a wide array of cross sections for the boom with the aim of weight saving. During the thesis both meshless and traditional finite element calculations are used when utilising simulation-driven design to optimise the boom. The study concludes that using a narrower octagonal cross section, improved material quality and adapting the positions of the mounts can decrease the weight by 23% with also decreasing the material cost by 13%.

SammanfattningTriply Periodic Minimal Surface (TPMS)-baserade nätverksstrukturer har snabbt blivit populära i flera tillämpningar, exempelvis medicinska implantat, värmeväxlare, stötdämpareoch lättviktskonstruktioner. Gyroidstrukturen är förmodligen den mest kända och använda, men en mängd varianter existerar med extremt goda egenskaper vid additiv tillverkning. Nätverkenkan printas helt utan stödstrukturer och kan erhålla mekaniska egenskaper i nivå̊ med de relativa bulkegenskaperna. I detta projekt skall mekaniska egenskaper för TPMS-baserade provbitar SLS-printade i PA11 undersökas genom dragprov, böjprov, slagseghetsprov och kompressionsprov. Dessutom ska det undersökas om byggriktning och orientering i skrivarens byggkammare har betydelse för materialets mekaniska egenskaper. Utöver detta kommer även en materialmodell byggas upp för analys med hjälp av Abaqus.Slutsatserna från examensarbetet var att både byggriktning och orientering i skrivarens kammare har betydelse för materialegenskaperna. Med resultaten från proverna ges rekommendationen att rikta stavarna från kammarens dörr inåt och med orienteringen liggandes. Även drogs slutsatsen att nätverksstrukturer når upp i nivå med de relativa bulkegenskaperna för trepunkts böjprov, dock endast med en ram runt hela provbiten. Det räckte ej med endast ram under och över / Triply Periodic Minimal Surface (TPMS)-based structures have quickly become popular inmany applications, for example medicinal implants, heat exchangers, shock absorbers and lightweight constructions. The gyroid structure is probably the most known and used, but plenty of variations exist with extremely good properties for additive manufacturing. The networks can be printed completely without support structures and can obtain mechanical properties in line with the relative bulk properties.This project shall evaluate the mechanical properties of TPMS-based test specimens SLSprinted in PA11 through compression testing, tensile testing, impact testing and three-point flexural testing. It shall also be determined if build direction and orientation in the printer’s build chamber effects the material’s mechanical properties. In addition to this will a material model be constructed for finite element analysis in Abaqus.The conclusions from this bachelor’s thesis are that both build direction and orientation in the printer’s build chamber effects the material mechanical properties. Based on the results from the tests the recommendation is given to direct the test specimens inward from the chamber’s door and to orient the specimens flat. The conclusion is also drawn that network structures can reach the relative bulk properties in three-point flexural test, however only with a frame encompassing the entire specimen. A frame only on top and bottom wasn’t enough.

Denna projektrapport beskriver arbetet för en kvalitativ produktutveckling av ett åkdon som ska brukas i Persåsens anläggning för kälkåkning. Syftet med projektet var att bredda kunskapen och förståelsen om vad som bidrar till en hållfast, bekväm och säker kälke. Kälken ska naturligt uppmuntra till en aktiv körställning. Detta genom att undersöka och utvärdera vilka möjliga lösningar det finns för ramkonstruktion, skidor och knästöd. Projektets resultat skulle i framtiden bidra till att kälkåkningen utvecklas till en säkrare, bekvämare aktivitet som är anpassad för en bredare kategori av användare. Projektets mål är att leverera ett förslag på en ramkonstruktion i form av en 3D-modell som uppfyller samtliga krav från upprättad kravspecifikation. FEM-analyser som redovisar att ramkonstruktionen klarar av lasten som dubbla maximala rekommenderad vikt på användare genererar på 3 kritiska punkter. Projektet skall även resultera i en 3D-modell som visar på ett designförslag av knästöd samt skidor. Utöver detta konceptförslag innehåller resultatet från det här projektet en konkurrensanalys, prototypbygge och experimentella data från ett användartest. Sistnämnda tre punkters resultat har legat som underlag för konstruktion- och designförslag. / This project report describes the work for a qualitative product development of a vehicle to be used in Persåsen's sledding facility. The purpose of the project was to broaden the knowledge and understanding of what contributes to a strong, comfortable and safe sled. The sledge should naturally encourage an active driving position. This is done by investigating and evaluating the possible solutions for frame construction, skis and knee supports. The results of the project would in the future contribute to the sledge riding being developed into a safer, more comfortable activity that is adapted for a wider category of users. The project's goal is to deliver a suggestion for a frame construction in the form of a 3D model as a complete criterion from established requirements specification. FEM analyzes that report that the frame construction can handle the load as double the maximum recommended weight of what a user generates at 3 critical points. The project will also result in a 3D model that shows a design suggestion of knee supports and skis. In addition to this concept suggestion the results from this project contains market analysis, prototype construction and experimental data from a user test. The latter three points' results have been the basis for construction and design suggestions. / <p>2022-07-01</p>

No description available.

<p>The Mechanics of Structural Genome (MSG) is a unified homogenization theory used to find equivalent constitutive models for beam, plate, and solid structures. It has been proven accurate for periodic structures. However, for certain applications such as non-prismatic wind turbine blades and helicopter flexbeams featuring ply drop-off, where there is no repeating structure and the periodic boundary condition cannot be used, MSG's accuracy is limited. In this work, we aim to extend MSG to find element stiffness matrices directly for aperiodic structures, instead of beam properties or three-dimensional (3D) solid material properties. Two finite elements based on MSG have been developed: Heterogeneous Beam Element (HBE) and Heterogeneous Solid Element (HSE).</p> <p><br></p> <p>For beam modeling, the beam-like structure is homogenized into a series of 3-node Heterogeneous Beam Elements (HBE) with 18×18 effective beam element stiffness matrices. These matrices are used as input for one-dimensional (1D) beam analysis using the Abaqus User Element subroutine (UEL). Using the macroscopic beam analysis results as input, we can also perform dehomogenization to predict the stresses and strains in the original structure. We use three examples (a prismatic composite beam, an isotropic homogeneous tapered beam, and a composite tapered beam) to demonstrate the capability of HBE and show its advantages over the MSG cross-sectional analysis approach. HBE can capture macroscopic behavior and detailed stresses due to non-prismatic geometry.</p> <p><br></p> <p>The Heterogeneous Solid Element (HSE) is developed based on MSG to model a heterogeneous body as an equivalent solid element using an effective element stiffness matrix. HSE modeling includes homogenization, macroscopic global analysis, and dehomogenization to recover local strains/stresses. HSE avoids the local periodicity assumption for traditional multiscale modeling techniques for composite structures that compute effective material properties instead. Abaqus composite solid element and MSG-based traditional multiscale modeling are used to validate the accuracy of HSE. All example results show that HSE is more accurate in predicting global structural behavior and local strains/stresses.</p> <p><br></p> <p>HBE and HSE provide a new concept for modeling aperiodic composite structures by modeling structures into equivalent beam or solid elements instead of beam properties of the reference line in 1D beam analysis or material properties of material points in solid structural analysis.</p>

No description available.

Design decisions have a large impact early in the design process. Optimization methods can help engineers improve their early decision making, however, design problems are often ill-posed for optimization at this early stage. This thesis develops engineering methods to use optimization during embodiment design, despite these difficulties. One common difficulty in designing mechanical systems is in handling the effects that design changes in one subsystem have on another. This is made more difficult in early engineering design, when design information is preliminary. Increased efforts have been made to use numerical optimization methods in early engineering design – because of the large impact early decisions have on subsequent development activities. One step toward executing meaningful optimizations in early design is the development of an optimization framework to be used when conditions are expected to change as the design progresses and new information is gained. This thesis presents a design framework that considers such change by subjecting the parametric updating of CAD models to optimization criteria specific to the problem at hand. Under the proposed framework, a part or subassembly is parametrically modeled in CAD; when changes are made to the subsystems that interact with the part or subassembly, it is then updated subject to design objectives and constraints. In this way, the updated part or subassembly satisfies system and subsystem level optimization criteria, reducing the need for the designer to react to design changes manually. It is used to reduce the weight of a Formula SAE suspension rocker by 18%, demonstrating the utility of this framework. Next, we develop methods to help engineers by giving them options and helping them explore during configuration generation. The design of multiple-bend, progressive-die-formed springs typically comprises four steps: (i) functional specification, (ii) configuration generation, (iii) configuration selection, and (iv) detailed shape and size optimization. Configuration generation fundamentally affects the success or failure of the design effort. This presents an important problem: by not generating potentially optimal configurations for further development in detailed design, the designer may unknowingly set the design on track for sub-optimal performance. In response, a method is developed that improves configuration generation. Specifically, an optimization-based spring configuration generator – without which, the generation would typically be based solely on designer creativity, experience, and knowledge. The proposed approach allows the designer to explore numerous optimization-generated spring configurations, which feasibly satisfy the functional specifications. The feasibility study is carried out before a final configuration is chosen for detailed development. Thus streamlining the designer's efforts to develop a design that avoids sub-optimality. We use the feasibleconfiguration generator to identify twenty-two electrical contact spring configurations. All twenty-two of the configurations satisfy the design's functional specifications. Two important concepts that improve decision making in early design were chosen. First, is the concept of a paremetric CAD based framework. Second is the concept of generating iso-performing design solutions. A numerical computer-based application is explained that takes advantage of these two ideas. A genetic algorithm topology optimization framework with the ability to converge to iso-performing solutions was integrated with CATIA V5. This application is demonstrated on a Formula SAE frame where it develops a pareto frontier of designs, expands upon one compromise design by producing iso-performing solutions, and automatically produces designs with the same performance after a parametric suspension change.

The purpose of this research is to develop and architect a preliminary multidisciplinary design optimization (MDO) tool that creates multiple types of generalized rocket fairing models. These models are sized relative to input geometric models and are analyzed and optimized, taking into account the primary objectives, namely the structural, thermal, and aerodynamic aspects of standard rocket flights. A variety of standard nose cone shapes is used as optimization proof of concept examples, being sized and compared to determine optimal choices based on the input specifications, such as the rocket body geometry and the specified trajectory paths. Any input models can be optimized to their respective best nose cone style or optimized to each of the cone styles individually, depending on the desired constraints. Two proof of concept example rocket model studies are included with varying sizes and speeds. Both have been optimized using the processes described to provide delineative instances into how results are improved and time saved. This is done by optimizing shape and thickness of the fairings while ascertaining if the remaining length downstream on the designated rocket model remains within specified stress and temperature ranges. The first optimized example exhibits a region of high stress downstream on the rocket body model that champions how these tools can be used to catch weaknesses and improve the overall integrity of a rocket design. The second example demonstrates how more established rocket designs can decrease their weight and drag through optimization of the fairing design.

Collaboration in engineering product development leads to shorter product development times and better products. In product development, considerable time is spent preparing the CAD model or assembly for Finite Element Analysis (FEA). In general Computer-Aided Applications (CAx) such as FEA deter collaboration because they allow only a single user to check out and make changes to the model at a given time. Though most of these software applications come with some collaborative tools, they are limited to simple tasks such as screen sharing and instant messaging. This thesis discusses methods to convert a current commercial FEA pre-processing program into a multi-user program, where multiple people are allowed to work on a single FEA model simultaneously. This thesis discusses a method for creating a multi-user FEA pre-processor and a robust, stable multi-user FEA program with full functionality has been developed using CUBIT. A generalized method for creating a networking architecture for a multi-user FEA pre-processor is discussed and the chosen client-server architecture is demonstrated. Furthermore, a method for decomposing a model/assembly using geometry identification tags is discussed. A working prototype which consists of workspace management Graphical User Interfaces (GUI) is demonstrated. A method for handling time-consuming tasks in an asynchronous multi-user environment is presented using Central Processing Unit (CPU) time as a time indicator. Due to architectural limitations of CUBIT, this is not demonstrated. Moreover, a method for handling undo sequences in a multi-user environment is discussed. Since commercial FEA pre-processors do not allow mesh related actions to be undone using an undo option, this undo handling method is not demonstrated.

One obstacle preventing more engineers from using finite element analysis (FEA) is the difficulty of transferring data between steps in the modeling process. A Fortran computer program, Rosetta.BYU, has been developed to open data paths between finite element preprocessors (mesh generators) and finite element analysis programs, using a custom data structure. It accepts neutral data files, Version 2.0 IGES data files, and Movie.BYU files for input/output. An application of Rosetta is described. A general workstation manager program, Davinci.BYU, is reviewed that provides a support layer between the engineer and the operating system, organizes software and data files, and facilitates on-line documentation and demonstrations. Requirements of a good user interface are discussed and supporting software, Squire.BYU, is described. An application of this software in an industrial setting is described.