In stamping operations, sheet metal is formed into a desired shape by pressing it in a hydraulic or mechanical press between suitably shaped dies. As a predominant manufacturing process, sheet metal forming has been widely used for the production of automobiles, aircraft, home appliances, beverage cans and many other industrial and commercial products. A major effort till date on stamping processes monitoring has been focused on investigating variations in the press force. Given that the press force itself is an integral of the contact pressure distribution over the die and binder contact interfaces, it is conceivable that defects may be better identified by analyzing the contact pressure distribution directly at the tooling-workpiece interface, instead of measuring the press force, which is less reflective of the localized forming process due to its nature as a secondary effect. It is thus desirable that a new, integrated sensing method capable of directly assimilating forming pressure distribution in the tooling structure be devised for improved stamping process monitoring. Designing such a distributed sensing scheme and analyzing the feasibility of its structural integration into a stamping tooling structure is the objective of this reported work. In this context, four research tasks have been identified and examined during the course of this work: 1) Devising a New, Embedded Sensing Method The new sensing method monitors stamping processes by means of an array of force sensors structurally integrated into the stamping tooling. The ability to directly measure local forming events by means of such an integrated and distributed sensing provides a new means of performing defect detection and process monitoring. Such a distributed sensing system overcomes the limitations of traditional tonnage and acceleration sensing systems which are focused on the measurement of indirect, global parameters. The new method is based on the evaluation of spatially continuous pressure surfaces from spatially discrete sensor measurements that are directly related to the local events at the stamping interface. To evaluate the effectiveness of this method, a panel stamping test bed equipped with an array of embedded force sensors has been designed, modeled and fabricated. Data obtained from experiments conducted on the test bed indicates that the new sensing method can be highly effective in process monitoring of stamping operations. 2) Reconstruction of Spatio-Temporal Distribution of Contact Pressure Structurally integrating sensors under tooling surfaces reduces the surface rigidity of the tool, thus limiting the number of sensors and the locations at which they can be embedded. This in turn affects the reconstruction of contact pressure distribution on the tooling surface. Numeric surface generation methods, such as Bezier surfaces and Thin Plate Spline surfaces offer a method for estimating the contact pressure distributions on the tooling surfaces from a sparse distribution of sensors. The concept of interpolating force distributions using surfaces has been investigated by researchers previously. However, selection of the surface generation method has remained largely an ad hoc process. The work presented here addresses this issue by using tooling interface contact pressure distribution information obtained from FE simulations as the basis for evaluating the accuracy of two commonly employed surface methods mentioned above. In order to reach a generic conclusion, the mathematical background of these schemes has been examined in light of the purpose at hand. The results indicate that an interpolative scheme such as the Thin Plate Spline surfaces (TPS), which can estimate the contact pressure distributions more accurately in a multi-sensor environment. The local and global accuracies of the Thin Plate Spline surface modeling technique have been experimentally evaluated using a sensor embedded stamping test bed designed for the purpose. 3) Modeling of Contact Pressure Distribution at the Sheet Metal-Tooling Interface Information about the contact pressure distribution at the tooling interface is critical to identifying the accuracy of numeric schemes that estimate by interpolation or approximation the contact pressure at any point on the tooling surface, based on a limited number of spatially distributed sensors. Furthermore, such knowledge is valuable in identifying operational parameters for the sensors to be integrated into the stamping tooling structure. In the absence of a tractable analytic method of determining the contact pressure distribution on stamping tooling surfaces, Finite Element models of a stamping operation have been created. Furthermore the drilling of sensor cavities under the working surfaces of the dies adversely affects the working life of stamping dies and their strength. The accuracy of analytic fatigue failure mechanics in evaluating the effect of parameters, such as embedding depth and sensor rigidity, on the operational life of the die, suffers from uncertainty in the estimation of stress concentrations around sharp geometric features of the sensor cavity. This shortcoming has been circumvented by the creation of FE models of the sensor cavity for more accurate estimation of stress concentrations around sharp geometries. The effect of different embedding materials on the sensitivity of embedded sensors has also been evaluated based on these models. 4) Defect Detection in Stamping Operation The ultimate goal of this thesis research was to study the feasibility of identifying defects in a stamping process based on the contact pressure distribution surfaces. This was achieved in this reported work by spatio-temporal decomposition of ‘parameters’ derived from the contact pressure distribution surfaces. Here ‘parameters’ refers to quantities such as the minimum, maximum, and mean contact pressures. These parameters have a time-varying spatial location as well as magnitude value associated with them. The feasibility of defect detection in stamping operations based on such parameters has been investigated. In addition to these focal areas, the design and implementation of a stamping test bed equipped for distributed contact pressure sensing has also been researched. This test bed was utilized for experimental verification of the developed theories and numerical models. Design of the proposed test bed required research into additional topics like the design of a protective package for embedded sensors and the effect of sensor embedding depth on contact pressure measurements. These issues have been addressed in this work, culminating in the experimental demonstration of the embedded pressure sensing system for process monitoring in the sheet metal stamping processes.

In endoprosthesis surgery there are typically a high percentage of implant defects, these can lead to failure of the whole prosthesis. One type of total hip replacement function loss is acetabular cup loosening from the pelvic bone. This disertation examines manufacture perturbations as one of the possible reasons for this kind of failure. Both dimension and geometry manufacturing perturbations of ceramic head and polyethylen cup were analyzed. We find that perturbations in the variables analysed here affect considered values of contact pressure and frictional moment. Furthermore, contact pressure and frictional moment are quantities affecting replacement success and durability. From obtained results it can be recommended to fit head and cup with a clearance of between 0 mm and 0.05 mm. It can not be recommend using interference type of fit because of strong deterioration of the contact conditions. Roundness perturbation of ceramic head should not exceed 0.025 mm.

Although steady progress has been made towards the development of a wearable pulse oximeter to aid in remote physiological status monitoring (RPSM) and triage operations, the ability to extract accurate physiological data from a forehead pulse oximeter during extended periods of activity and in the presence of pressure disturbances acting on the sensor remains a significant challenge. This research was undertaken to assess whether the attachment method used to secure a pulse oximeter sensor affects arterial oxygen saturation (SpO2) and heart rate (HR) accuracy during motion. Additionally, two sensor housings were prototyped to assess whether isolating the sensor from external pressure disturbances could improve SpO2 and HR accuracy. The research revealed that measurement accuracy during walking is significantly affected by the choice of an attachment method. Specifically, the research indicated that an elastic band providing a contact pressure of 60 mmHg can result in decreased measurement error and improved reliability. Furthermore, the research validated that the two isolating housings we have investigated improve SpO2 and HR errors significantly at pressures as high as 1200 mmHg (160 kPa) compared to current commercial housings. This information may be helpful in the design of a more robust pulse oximeter sensor for use in RPSM.

This diploma thesis is engaged in calculation of contact pressure from thickness of lubricating film using Finite Element Method (FEM). Within my diploma thesis were performed the calculations concerning to non-conformal surfaces with a view to elastohydrodynamic lubrication. The simulations were done for disk and ball contact, respectively with burnished finish and also with surface which contains small dent. Flow diagram was designed so that the creation of geometry, boundary conditions and results saving is controlled parametrically. With using parameters it is possible to repeat the calculation when the resolution, geometry, etc. will be changed.

The master’s thesis contains a plan of hinged adapter for cord header Cornpower 8-75 of the BISO Schrattenecker Company. The adapter is designed for threshing machines New Holland. The thesis includes a comparison of the mechanisms used by competitors. Further it contains design of the entirely different mechanism, its kinematics solution of the hydraulic circuit and calculating of the strength using FEM method, including calculation of contacts. The drawing documentation is done in Catia V5 and strength calculations in NX-Ideas and Marc 2010.

Today is on products from the perspective of quality placed an increasing emphasis. This work is focused to the analyze of cross roll straghtening of long semifinished products with a circular cross-section. This process increased quality of semifinished products from the perspective of their curvature, because they do not reach the required limit values. Curvature of the semifinished product is due to residual stress, which is during straghtening using plastic deformation of the material redistributed and the semifinished product is leveled. This work analyzes the effect of rotation of straightening rolls on the distributiom of contact pressure between the straightening semifinished product and the roll of straightener. Author then analyzes effect of input parameters of program to straightening at the final curvature of the semifinished product. With the experience gained, then try to adjust some input parameters.

In endoprosthesis surgery there are typically a high percentage of implant defects, these can lead to failure of the whole prosthesis. One type of total hip replacement function loss is acetabular cup loosening from the pelvic bone. This disertation examines manufacture perturbations as one of the possible reasons for this kind of failure. Both dimension and geometry manufacturing perturbations of ceramic head and polyethylen cup were analyzed. We find that perturbations in the variables analysed here affect considered values of contact pressure and frictional moment. Furthermore, contact pressure and frictional moment are quantities affecting replacement success and durability. From obtained results it can be recommended to fit head and cup with a clearance of between 0 mm and 0.05 mm. It can not be recommend using interference type of fit because of strong deterioration of the contact conditions. Roundness perturbation of ceramic head should not exceed 0.025 mm.

About 3/4th percentage of Earth’s surface is covered with water, the demand for harnessing energy from the ocean is increasing periodically. This form of energy conversion is Wave Energy. This method is practised all around the world, Novi-Ocean by Novige AB is one of its kind where they aim to build a wave energy converter. The main component of the device is the oating platform above the sea level and powertake-o (cylinder) below the sea level. The motion of waves makes the platform to move vertically up and down thus creating a lift force 450 tons. The force is experienced at the interface of platform and cylinder attachment. Therefore, a conceptual design for distributing the force along the length of the shaft is necessary. Also, suitable bearing for the marine application needs to be selected. For the application mentioned relevant research is made on understanding the types of the wave energy converter and their working principles. The product development methodology is carried out to generate a conceptual design. Next, simulations were performed to decide the diameter of the shaft at the interface. A numerical and FEA model analysis of press- t is performed to check the contact pressure. / Cirka 3/4 procent av jordens yta är täckt med vatten, efterfrågan på att utnyttja energi från havet ökar periodvis. Denna form av energiomvandling är Wave Energy. Denna metod utövas över hela världen, Novi-Ocean av Novige AB är ett i sitt slag där de syftar till att bygga en vågenergikonverterare. Huvudkomponenten i enheten är den ytande plattformen över havsnivån och kraftuttaget (cylinder) under havsnivån. Vågens rörelse gör att plattformen rör sig vertikalt upp och ner och skapar en lyftkraft 450 ton. Kraften upplevs vid gränssnittet mellan plattform och cylinderfäste. Därfor är en konceptuell design för fördelning av kraften längs axelns längd nödvändig. Dessutom måste lämpligt läger för den marina applikationen väljas. För den nämnda applikationen görs relevant forskning for att förstå typerna av vågenergikonverteraren och deras arbetsprinciper. Produktutvecklingsmetodiken genomförs för att generera en konceptuell design. Därefter utfördes simuleringar för att bestämma axelns diameter vid gränssnittet. En numerisk och FEA-modellanalys av presspassning utförs för att kontrollera kontakttrycket.

Yes / A 2D coupled temperature-displacement FE model is developed for a pad-disc brake system based on a restricted rotational pad boundary condition. The evolution of pressure, heat flux, and temperature along the contact interface during braking applications is analysed with the FE model. Results indicate that different rotational pad boundary conditions significantly impact the interface pressure distribution, which in turn affects interface temperature and heat flux distributions, and suggest that a particular pad rotation condition is most appropriate for accurately modelling friction braking processes. The importance of the thermal contact conductance in the analysis of heat transfer in friction braking is established, and it is confirmed that the heat partition ratio is not uniformly distributed along the interface under normal and high interface thermal conductance conditions.

Elastomer seals are used in a variety of industries that require flow isolation. The characterization of the behavior of these seals remains largely unexplored and hence, this study is focused on simulating and validating the axial-compressive behavior of an annular rubber seal constrained concentrically in a pipe. The elastomer material composing the seal, was experimentally characterized for its mechanical, frictional, and viscoelastic properties and modelled using models developed by Yeoh, Thirion, and Prony respectively. A 2D axisymmetric finite-element model was developed using ANSYS 16 and used alongside the material models to simulate an axial load versus displacement curve, a contact pressure distribution, and a pipe hoop strain gradient. The results for quasi-static loading and viscoelastic effects agreed within 7% and 18% of the experimental results, respectively. It was observed that pipe geometry, rubber chemistry, frictional properties, and viscoelastic effects have significant effect on the compressive behavior of the seal. / October 2016