Concrete design rules can facilitate the designer to depict capable design and reliable products. However, it is difficult to deduce systematic design rules from previous experience and to modify the rules in a rule-based system. In the last decade, Case-Based Reasoning (CBR) has become an important methodology to solve the problem. The objective of this paper is to determine the appropriate case representation used in assembly part design for developing a CBR system. The designer can obtain real-time Early experimental results indicate that the case representation can appropriately represent the expertise and experience of assembly part design based on CBR methodology.

Indiana University-Purdue University Indianapolis (IUPUI) / One of the primary challenges faced in Additive Manufacturing (AM) is reducing the overall cost and printing time. A critical factor in cost and time reduction is post-processing of 3D printed (3DP) parts, which includes removing support structures. Support is needed to prevent the collapse of the part or certain areas under its own weight during the 3D printing process. Currently, the design of self-supported 3DP parts follows experimental trials. A trial and error process is needed to produce high quality parts by Fused Depositing Modeling (FDM). An example for a chamfer angle, is the common use of 45 degree angle in the AM process. Surfaces that are more flat show defects than inclined surfaces, and therefore a numerical model is needed. The model can predict the problematic areas at a print, reducing the experimental prints and providing a higher number of usable parts. Physical-based models have not been established due to the generally unknown properties of the material during the AM process. With simulations it is possible to simulate the part at different temperatures with a variety of other parameters that have influence on the behavior of the model. In this research, analytic calculations and physical tests are carried out to determine the material properties of the thermoplastic polymer Acrylonitrile - Butadiene - Styrene (ABS) for FDM at the time of extrusion. This means that the ABS is going to be extruded at 200C to 245C and is a viscus material during part construction. Using the results from the physical and analytical models, i.e., Timoshenko’s modified beam theory for micro structures, a numerical material model is established to simulate the filament deformation once it is deposited onto the part. Experiments were also used to find the threshold for different geometric specifications, which could then be applied to the numerical model to improve the accuracy of the simulation. The result of the nonlinear finite element analysis is compared to experiments to show the correlation between the prediction of deflection in simulation and the actual deflection measured in physical experiments. A case study was conducted using an application that optimizes topology of complex geometries. After modeling and simulating the optimized part, areas of defect and errors were determined in the simulation, then verified and and measured with actual 3D prints.

In our fickle economy today, retail can be booming one year and going out of business the next. When things aren't going so well commercial retail buildings are left vacant and then can become eyesores that lead to a communities economic downturn. This thesis proposes a solution by designing commercial buildings for re-use by designing for deconstruction; so that whole buildings can be disassembled and relocated, or that building components can be recycled back into the materials loop.

Detta arbete behandlar ett problem som har uppstått hos svetsföretaget ESAB AB i Laxå, då ett trådbyte ska ske av en tråd med en vikt på 100 kg i en svetsmaskin. Svetstråden sitter mellan en spole som består av en undre och övre del som skruvas fast i varandra. Spolen är därefter monterad i en arm längst bak på svetsmaskinen. Problemet med trådbytet är dels att tråden väger mycket, dels att bytet behöver genomgå flera olika steg. Först av allt lyfts den spolen med förbrukad tråd av med hjälp av en travers och läggs på marken. Sedan skruvas den övre delen av spolen av och den förbrukade svetstråden tas bort för hand. En ny trådrulle hämtas därefter med en travers och placeras sedan på den undre delen av spolen. Den övre delen av spolen hämtas efter detta, för att skruvas fast tillbaka på spolen tillsammans med trådrullen och spolens undre del. När dessa steg är genomförda lyfts spolen tillbaka på svetsmaskinens arm och skruvas fast. Svetsmaskinens arm kan bära upp till fyra spolar samtidigt. Ovanstående steg tar upp tid från arbetet som behöver genomföras och är dessutom tungt då enbart spolen väger 27 kg, utan en trådrulle monterad. Lösningen till problemet är att implementera metodiken Design For Assembly (DFA), med syftet att minimera monteringstiden och fortsätta med en produktutvecklingsprocess av spolen och svetsmaskinens arm, där spolen sitter monterad på.   Resultatet på lösningen presenteras med hjälp av ritningar i CAD, i både 3D och 2D, samt beräkningar. Anledningen till att presentationen görs med hjälp av CAD- ritningar är för att tydliggöra lösningens koncept samt för att kunna påvisa hur metodikerna har använts vid lösningen. Lösningarna har jämförts och övervägts med Pughs matris. Med de beräkningar som gjorts har även hållfastheten kunnat räknats ut för lösningen. Syftet och frågeställningen besvarades för detta arbete.  Den största skillnaden mellan detta arbetes slutgiltiga lösning och ESAB AB:s redan existerande lösning är att enbart den övre delen av spolen behöver skruvas av vid trådbyte. Detta gör att många moment kan elimineras, vilket i sin tur förkortar monteringstiden och mer tid kan ägnas åt arbete i svetsningen. / This thesis deals with a problem that has arisen at the welding company ESAB AB in Laxå, when changing 100 kg thread spools in a welding machine. The wire sits between a spool consisting of a lower and upper part that are screwed together. The spool is then mounted in an arm at the back of the welding machine.  The problem with the spool change is partly that the spool weighs a lot, and partly that the change needs to go through several different steps. First, the spool with used wire must be lifted off with a traverse and laid on the ground. Then the upper part of the spool needs to be unscrewed to remove the used wire by hand. Then is brought with a help of a traverse. The wire is then placed on the lower part of the spool. The upper part of the spool is then retrieved and gets screwed on. When these steps are completed, the spool gets lifted back onto the welding machines arm with the traverse and gets mounted on.  The welding machine's arm can have up to four spools mounted simultaneously. These steps take up time from the work that needs to be done and are also heavy. The solution to the problem is to implement the Design for Assembly (DFA) methodology, with the aim of minimizing assembly time and continuing with a product development process of the spool and the arm that the spool is on.  The results of the solution are presented with the help of drawings in both 3D and 2D CAD drawings as well as calculations. The reason why the presentation is made with the help of CAD drawings is to clarify the concept of the solution and to be able to demonstrate how the methodologies have been used in the development. The solutions have been compared and weighted with Pugh's matrix. With the calculations that have been made, it has also been possible to calculate the strength of the solution. The purpose and question were answered for this work. The biggest difference between this work's final solution and ESAB AB's already existing solution is that only the upper part of the spool needs to be unscrewed when changing wires. This means that many steps can be eliminated, which in turn shortens the assembly time and more time can be devoted to work.

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Exoskeletons are rapidly emerging from the realm of science-fiction myth to practical reality in everyday life. Various designs have provided viable means for individuals to regain capabilities that were lost or perform tasks not previously possible by their ability alone. In this research, I propose two novel exoskeletons for walking assistance and heavy load carriage. The first exoskeleton can be used to provide assistance for walking in various applications such as industrial productivity, rehabilitation, and military or space training. We introduce a design for a lower body wearable device that supports up to 80% of the user's body weight (667 N peak force) with a single actuator on each leg. Its underactuated design directs force through the user's center of mass with a single sprocket-chain driven prismatic actuator on each leg, allowing for natural gait and mobility. The device is optimized for simplicity, ease of assembly, low cost, and weight. The second design aims to counteract the one of the leading causes of injury in the workplace, repetitive and heavy lifting. The Heavy Lift and Carry Exoskeleton (HeavyLC Exo) is capable of safely lifting and carrying loads up to 36 kg (80 lbs) while minimizing the number of actuators to reduce weight and complexity. The HeavyLC Exo allows the user to direct the object, pause and hold the object steady mid-lift, and follow the natural kinematics of lifting. It is secured to the user with shoulder, chest, and dual thigh straps, along with an adjustable waist belt and overshoe attachment. Powered by two 14.8 V batteries and an off-board air compressor, the HeavyLC Exo has a total of 20 DOF, with 6 actuated DOF and 14 free DOF. The arms use only two actuators each, providing powered lifting and arm retraction/extension, and allowing a wide range of body postures; the legs are powered by single pneumatic actuators on each leg connected to the foot accompanied by a passive spring element to prevent excessive pelvic tilt and leg abduction during swing. The control system requires directional forces from the user at the tool handle of 19 N (4.3 lbf) on average. Current design limitations necessitate the user to provide up to 280 N (62.9 lbf) at the hip during worst load conditions, and future design optimization is proposed. A fully functional prototype of HeavyLC Exo is built, fully tested, and analyzed for improvement. / Master of Science / Exoskeletons, which were once only seen in science fiction, are now becoming a reality in everyday life. Various designs have made it possible for people to do things they couldn't do before or regain abilities they lost. In this research, two new exoskeletons are proposed - one for walking assistance and the other for carrying heavy loads. The first exoskeleton is designed to help people walk. It supports up to 80 % of the user's body weight with a single actuator on each leg, which directs force through the center of mass, allowing for natural gait and mobility. It's simple, easy to assemble, low-cost, and lightweight, making it useful in various applications such as medical rehabilitation, military or space training, and industrial productivity. The second exoskeleton is designed to help people lift and carry heavy objects, which is a common cause of workplace injuries. The Heavy Lift and Carry Exoskeleton (HeavyLC Exo) can safely lift and carry objects up to 36 kg (80 lbs) while minimizing the number of actuators to reduce weight and complexity. It's worn by the user using shoulder, chest, and dual thigh straps, along with an adjustable waist belt and overshoe attachment. The exoskeleton is powered by two batteries and an off-board air compressor, and has 20 degrees of freedom, with 6 powered and 14 non-powered, giving it significant flexibility to conform to lifting and walking motions allowing it to function with normal user range of motion. The arms use two actuators each to provide powered lifting and arm retraction/extension, while the legs are powered by single pneumatic actuators on each leg connected to the foot accompanied by a elastic spring element. The control system requires the user to lift and maneuver about 1.9 kg (4.2 lbs) to direct the object. A fully functional prototype has been built, tested, and analyzed for changes in the future.

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