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Master of Agribusiness / Department of Agricultural Economics / Ted C. Schroeder / The CNH Wichita Product Center has had a chronic leak problem with the Skid Steer Loaders. The objective of this project was to analyze the manufacturing plant leak data and make improvements to correct the issue. The objective is twofold: 1) to make process or design improvements on current products produced in the plant and 2) to make recommendations for future designs to prevent such leak issues from reoccurring. The manufacturing data had to be transformed into usable form and then it was analyzed mostly by utilizing Pareto Charts. The highest six problem leak points were chosen from the manufacturing data. Process changes were implemented on these particular leak joints and the results were analyzed using two proportions hypothesis tests. The process changes reduced the leak rate by an average percent reduction of 86 percent. The process changes implemented will also be applied to other similar joints, and results documented in the future. The future design recommendations made from the analyzed data included the increased use of o-ring face seal connections at certain locations and where possible, reducing the number of joints per machine.

In this dissertation, experimental investigations and theoretical studies on the stochastic matrix cracking evolution under static and fatigue loading in composite laminates with defects are presented. The presented work demonstrates a methodology that accounts for the statistically distributed defects in damage mechanics models for the assessment of the integrity of composites and for the structural design of composites. The experimental study deals with the mechanisms of the formation of a single crack on a micro-scale and the stochastic process for the multiplication of cracks on a macro-scale. The defects introduced by the manufacturing processes are found to have significant effect on the matrix cracking evolution. Influenced by the distributed defects, the initiation and multiplication of cracks evolve in a stochastic way. The experimental study on the in-plane shear stress finds the detrimental effect of the shear stress on the fatigue performance of composite laminates. Combined with the transverse tensile stress, the in-plane shear stress induces multiple inclined microcracks in the matrix, which enhance the initiation and propagation of the major matrix cracks. Based on the experimental investigations, a statistical model for the stochastic matrix cracking evolution on the macro-scale is developed. Simulations based on the statistical model yield accurate predictions for both static and fatigue loading compared to the experimental data. The Weibull distribution of the static strength is estimated by the statistical model by comparing against the experimental crack density data. The estimated Weibull distribution of the static strength provides an efficient approach to characterize the manufacturing quality of composite laminates. Compared to deterministic approaches, the Weibull distribution of the static strength provides comprehensive information of the strength property of composite laminates.

L'étude présente les méthodes pour identifier et simuler les défauts de fabrication tridimensionnels. Les méthodologies ont été élaborées sur la base des travaux antérieurs, tels que la méthode de simulation MMP (Model of Manufactured Part) présentée par F. Villeneuve et F. Vignat, associée à la méthode de la double mesure présentée par S. Tichadou.Dans cette thèse, la première méthode proposée, basée sur la méthode des petits déplacements (TPD) est présentée et permet l'identification des défauts de fabrication. Cette méthode permet de distinguer les défauts d'usinage et les défauts de positionnement d'un lot de pièces au cours d’un processus de fabrication. Les résultats obtenus dans cette méthode représentent les dispersions géométriques des pièces usinées. En outre, une méthode d’analyse modale de défauts a été réalisée pour analyser les défauts de forme d'une pièce mesurée sur une MMT avec un nombre restreint de points de mesure (10 points sur chaque surface usinée). Les résultats montrent que les modes des défauts de forme sont obtenus correctement (bombé, ondulation, vrillage, etc.)En raison de l'importance du rôle du défaut de positionnement dans la qualité d'un produit en cours de fabrication, ensuite deux indicateurs simples ont été proposés pour évaluer la qualité globale d’un montage de fixation de pièces.Par ailleurs, un modèle permettant de simuler les défauts de positionnement d'une pièce fixée sur un mandrin à trois mors a été développé. Le modèle final de simulation est une combinaison de trois méthodes: plan d’expérience, simulation par éléments finis, et simulation de Monte Carlo. Pour la méthode des plans d’expérience, trois facteurs, qui sont supposés être les plus importants dans les défauts de positionnement, sont utilisés dans le modèle. Les résultats obtenus à partir des simulations sont exprimés sous forme de distributions et de paramètres statistiques caractéristiques. Ceux-ci sont ensuite utilisés pour effectuer les simulations en appliquant la méthode de Monte Carlo.Enfin, un modèle global est proposé, pour simuler la gamme de fabrication d’une pièce fraisée. Ce modèle permet de vérifier la gamme choisie avec des tolérances fonctionnelles de la pièce imposée. De plus, cette méthode permet de vérifier une gamme de fabrication en garantissant les tolérances fonctionnelles imposées ou une utilisation inverse qui permet de déterminer les tolérances garantissant un nombre de pièces usinées hors des zones de tolérance. / The research presents methodologies to identify and simulate manufacturing defects in three-dimension. The methodologies have been developed based on the previous works, such as the MMP (Model of Manufactured Part) simulation method presented by F. Villeneuve and F. Vignat, and the double measurement method is presented by S. Tichadou.In this thesis, the first proposed method based on the Small Displacement Torsor (SDT) concept is presented for identification of manufacturing defects. This method allows distinguishing the machining defects and positioning defects of a batch of parts during a process plan. The results obtained in this method represent geometric dimension errors of machined parts. In addition, we applied the parameterization method, which is usually used to analyze form defects of a part measured on a CMM with hundreds of measurement points, to complete the analysis of the form defects with a restricted number of measurement points (10 points on each machined surface). Even though this number appears to be low, the modes of the form defects are almost obtained (comber, undulation, twist, etc).Because of the important role of the positioning defect in the quality of a product during manufacturing, we then propose two simple indicators for evaluating the global quality of a fixture.Furthermore, we developed a model for simulating positioning defects of a workpiece fixed on a three-jaw chuck. The model is a combination of three methods: design of experiments, finite element simulation, and Monte Carlo simulation. Three factors, which are assumed to be the most important in positioning defects, are used in this model. Based on the simulated results, the influences of these factors are estimated. The results obtained from simulations can be expressed by form of distributions or statistical parameters. These allow using simulation of tolerance analysis based on Monte Carlo simulation.Finally, a model is developed based on MMP for tolerance analysis. This model allows us to verify a given process plan with functional tolerances of the machined part by determination of a number of machined parts out of tolerance zones or determine functional tolerances of a batch of machined parts based on a given process plan (without functional tolerances) and a number of rejected parts per million.

The modern engineering design process includes computer software packages that require approximations to be made when representing geometries. These approximations lead to inherent discrepancies between the design geometry of a part or assembly and the corresponding manufactured geometry. Further approximations are made during the analysis portion of the design process. Manufacturing defects can also occur, which increase the discrepancies between the design and manufactured geometry. These approximations combined with manufacturing defects lead to discrepancies which, for high precision parts, such as jet engine compressor blades, can affect the modal analysis results. In order to account for the manufacturing defects during analysis, mesh morphing is used to morph a structural finite element analysis mesh to match the geometry of compressor blades with simulated manufacturing defects. The mesh morphing process is improved by providing a novel method to convert heteromorphic shape matching within Sculptor to homeomorphic shape matching. This novel method is automated using Java and the NX API. The heteromorphic to homeomorphic conversion method is determined to be valid due to its post-mesh morphing maximum deviations being on the same order as the post-mesh morphing maximum deviations of the ideal homeomorphic case. The usefulness of the automated heteromorphic to homeomorphic conversion method is demonstrated by simulating manufacturing defects on the pressure surface of a compressor blade model, morphing a structural finite element analysis mesh to match the geometry of compressor blades with simulated manufacturing defects, performing a modal analysis, and making observations on the effect of the simulated manufacturing defects on the modal characteristics of the compressor blade.

In this fast pace world, climate change is one of the primary concerns worldwide. The world is racing towards reducing CO2 emissions by focusing on decreasing energy consumption. Electric motors capture about two-third of the industrial energy consumption, of which the most growing sector is electrical vehicles. The precise design of electric motors requires an optimal estimation of the machine’s performance characteristics. In this master thesis, the impact on core losses of an electric machine (e-machine) due to laser cutting is studied. The impact is derived in terms of a mathematical model which is introduced in a finite element model of an e-machine to attain optimal performance characteristics. A customized Single Sheet Tester (SST) based measuring apparatus is developed. The measuring apparatus is used to characterize the magnetic materials (electrical steel) used in the core of an e-machine. The studies already presented in the literature compromise on maintaining the same material mass while characterizing the magnetic material. Thus, a novel approach is attempted in this work to maintain approximately the same mass for all test samples used for characterization. The samples under test are laser cut possessing different sample widths leading to different distances from the cut edge. The characterized samples are compared for magnetic properties such as permeability and core losses to derive a mathematical model to estimate the impact of degradation in electrical steel. The derived models are implemented in a reference Permanent Magnet Synchronous Machine (PMSM) to analyze the degradation effect on the loss and performance characteristics. The influence of laser cutting impacts drastically the iron losses at an average which increases by about 35 % with a corresponding reduction of 21 % in material permeability. There is an average increase in machine torque by about 2 % and the increase in the total iron losses leads to an average 0.5 % decrease in the efficiency of the machine. The increase in iron losses at lower magnetic flux densities is more significant compared to the saturation region. The maximum degradation effect in the material is nearer to the cutting edge and reduces going away from the cut-edge. The permeability in the material decreases closer to the cut edge and thus the maximum amount of flux gets enforced towards the center because of degradation. / I denna snabba värld är klimatförändringarna en av de främsta problemen världen över. Världen tävlar mot att minska CO2 -utsläppen genom att fokusera på att minska energiförbrukningen. Elmotorer tar upp ungefär två tredjedelar av den industriella energiförbrukningen, varav den mest växande sektorn är elfordon. Den exakta designen av elmotorer kräver en optimal uppskattning av maskinens prestandaegenskaper. I denna masteruppsats studeras inverkan på kärnförluster hos en elektrisk maskin (e-maskin) på grund av laserskärning. Effekten härleds i termer av en matematisk modell som åberopas i en Finite Element Modelling (FEM) av en e-maskin för att uppnå optimala prestandaegenskaper. En skräddarsydd SST-baserad mätapparat utvecklas. Mätapparaten används för att karakterisera de magnetiska material (elektriskt stål) som används i kärnan i en e-maskin. De studier som redan presenterats i litteraturen kompromissar med att bibehålla samma materialmassa samtidigt som de karakteriserar det magnetiska materialet. Således har ett nytt tillvägagångssätt försökts i detta arbete för att bibehålla ungefär samma massa för alla testprover som används för karakterisering. Proverna som testas är laserskurna med olika provbredder vilket leder till olika avstånd från den skurna kanten. De karakteriserade proverna jämförs för magnetiska egenskaper såsom permeabilitet och kärnförluster för att härleda en matematisk modell för att uppskatta effekten av nedbrytning i elektriskt stål. De härledda modellerna implementeras i en referens PMSM för att analysera nedbrytningseffekten på förlust- och prestandaegenskaper. Inverkan av laserskärning påverkar drastiskt järnförlusterna med ett genomsnitt som ökar med cirka 35% med en motsvarande minskning av 21 % i material permeabilitet. Det finns en genomsnittlig ökning av maskinens vridmoment med cirka 2 % och ökningen av de totala järnförlusterna leder till en genomsnittlig minskning av maskinens effektivitet med 0,5 %. Ökningen av järnförluster vid lägre magnetiska flödestätheter är mer signifikant jämfört med mättnadsområdet. Den maximala nedbrytningseffekten i materialet är närmare skäreggen och minskar bortgången från skärkanten. Permeabiliteten i materialet minskar närmare den skurna kanten och sålunda tvingas den maximala mängden flöde in mot mitten på grund av nedbrytning.