Eighteen splice specimens were tested under four-point loading as part of a larger experimental investigation to study the behaviour of lap spliced plain steel bars in reinforced concrete specimens. Three of the specimens were instrumented with strain gauges adhered to the reinforcement and the concrete side face. Three lap splice lengths, two bar sizes for square bars, and one bar size for round bars were investigated. The principal reinforcement was either cast in the bottom or top position. The results of maximum loads, crack patterns, load versus deflection behaviour, and deflected profiles are presented for all specimens. The analysis of specimens with strain gauge instrumentation is also presented, and includes results of strain compatibility, bond stress distribution, and flexural section analysis. All specimens failed by bond, caused by a sudden pullout of the reinforcement within the splice region. An equivalent round diameter based upon the cross-section area of the square bars allowed for a single predictive equation between the maximum normalized load as a function of splice length, casting position and bar size. A top cast factor of 0.4 and 0.6 captures the reduction in the maximum normalized load for specimens cast with round and square bars, respectively, in the top position. The CEB-FIP Model Code (1993) predictive equations are reasonably conservative in capturing the behaviour of specimens reinforced with round bars cast in the bottom position, and square bars with side dimension of 25 mm cast in the bottom position. However, the CEB-FIP Model Code (1993) predictive equation is unconservative when predicting the behaviour of specimens reinforced with either square or round bars cast in the top position. On the other hand, the draft CEB-FIP Model Code (2010) provisions showed an overly conservative prediction for all specimens reinforced with either round or square bars cast in the top or bottom position. Instrumented specimens showed that strain compatibility between the longitudinal reinforcement and the surrounding concrete did not exist for much of the loading range due to bond loss. The evaluation of the neutral axis location within the shear span showed that shear is first transferred by beam action, followed by arch action. The use of three strain gauges adhered to the concrete side face provided flexural moments similar to that predicted theoretically.

Defects in polyethylene film are often caused by contaminant particles in the polymer melt. In this research, particle properties obtainable from in-line melt monitoring, combined with processing information, are used to predict film defect properties. “Model” particles (solid and hollow glass microspheres, aluminum powder, ceramic microspheres, glass fibers, wood particles, and cross-linked polyethylene) were injected into low-density polyethylene extruder feed. Defects resulted when the polyethylene containing particles was extruded through a film die and stretched by a take-up roller as it cooled to form films 57 to 241mm in thickness. Two off-line analysis methods were further developed and applied to the defects: polarized light imaging and interferometric imaging. Polarized light showed residual stresses in the film caused by the particle as well as properties of the embedded particle. Interferometry enabled measures of the film distortion, notably defect volume. From the images, only three attributes were required for mathematical modeling: particle area, defect area, and defect volume. These attributes yielded two ”primary defect properties”: average defect height and magnification (of particle area). For all spherical particles, empirical correlations of these properties were obtained for each of the two major types of defects that emerged: high average height and low average height defects. Analysis of data for non-spherical particles was limited to showing how, in some cases, their data differed from the spherical particle correlations. To help explain empirical correlations of the primary defect properties with film thickness, a simple model was proposed and found to be supported by the high average height defect data: the “constant defect volume per unit particle area” model. It assumes that the product of average defect height and magnification is a constant for all film thicknesses. A numerical example illustrates how the methodology developed in this work can be used as a starting point for predicting film defect properties in industrial systems. A limitation is that each prediction yields two pairs of primary defect property values, one pair for each defect type. If it is necessary to identify the dominant type, then measurement of a length dimension of sufficient defects in the film is required.

No description available.

Defects in polyethylene film are often caused by contaminant particles in the polymer melt. In this research, particle properties obtainable from in-line melt monitoring, combined with processing information, are used to predict film defect properties. “Model” particles (solid and hollow glass microspheres, aluminum powder, ceramic microspheres, glass fibers, wood particles, and cross-linked polyethylene) were injected into low-density polyethylene extruder feed. Defects resulted when the polyethylene containing particles was extruded through a film die and stretched by a take-up roller as it cooled to form films 57 to 241mm in thickness. Two off-line analysis methods were further developed and applied to the defects: polarized light imaging and interferometric imaging. Polarized light showed residual stresses in the film caused by the particle as well as properties of the embedded particle. Interferometry enabled measures of the film distortion, notably defect volume. From the images, only three attributes were required for mathematical modeling: particle area, defect area, and defect volume. These attributes yielded two ”primary defect properties”: average defect height and magnification (of particle area). For all spherical particles, empirical correlations of these properties were obtained for each of the two major types of defects that emerged: high average height and low average height defects. Analysis of data for non-spherical particles was limited to showing how, in some cases, their data differed from the spherical particle correlations. To help explain empirical correlations of the primary defect properties with film thickness, a simple model was proposed and found to be supported by the high average height defect data: the “constant defect volume per unit particle area” model. It assumes that the product of average defect height and magnification is a constant for all film thicknesses. A numerical example illustrates how the methodology developed in this work can be used as a starting point for predicting film defect properties in industrial systems. A limitation is that each prediction yields two pairs of primary defect property values, one pair for each defect type. If it is necessary to identify the dominant type, then measurement of a length dimension of sufficient defects in the film is required.

This thesis work has been performed at the Division of Assembly Technology at Linköping University for a period of ten weeks. The work is part of the project ProFlexA, which is a research project in collaboration between Linköping University, Lund University, and industrial partners such as Combi Wear Parts and Smålands Stålgjuteri AB. The casting process creates random incurred burrs and defects, which must be removed during a cleaning process to make sure that the cast can be sold. Automation has long been sought for the cleaning of castings due to, among other things, poor working conditions for staff, but this has proved difficult to implement with today's technology. Automation has for some time been available for more capital strong companies with large annual volumes, but for smaller companies with small-and medium-sized volumes, automation has not been an option. The goal of ProFlexA is to develop an automated cleaning cell aimed at small-and medium-sized volumes. The goal of the thesis is to do a pre study at ProFlexA’s partners on cleaning of castings, and develop concepts for automated cleaning of castings. By recording the process and cycle times, the cleaning of castings has been documented as it works today, and on this basis, information and statistics has been compiled. Conclusions have been drawn on preventive measures that may facilitate the development of an automated cleaning cell.  One of these is to change the geometry of the steel riser so that the resulting stub after removal by the pneumatic hammer is more controlled, and another measure is to relocate the location of the riser stub to an equal side of all the products. It is also important to prevent the defect caused by sand residues. Based on the documentation, it has been revealed that the product often is over-worked, which implies that an automated cell would provide a more even quality.   Forces that occur in an operation of cleaning of castings have been measured. The results suggest that the forces in this context are 100 to 180 Newton, which indicates that the robot selected to the project, IRB 6660, is likely to be oversized. It can therefore be discussed if it is relevant with the current safety factor or if there is a reason to search for a smaller robot. Proposals have been prepared on concepts of automated cleaning of castings. These concepts show how a robotic cell can work when a single robot, compared with two robots are part of a cell, but also how it works with stationary tools compared with mobile tools. The design of a robotic cell should be sought in the objectives and needs of the specific company. A robotic cell with two robots is for example to be preferred when the need for efficiency is higher. Tools to a robotic cell is built in the simplest possible terms by a motor, a spindle and a tool, which is the option that seems to be a good choice in terms of whole and investment friendliness. For Combi Wear Parts a robotic cell with two robots is suitable, and for Smålands Stålgjuteri AB a robotic cell with a single robot is probably the best choice. For both of these solutions small and economic stationary tools would probably suit well.

The need for lighter weight vehicles to improve fuel efficiency is becoming increasingly imperative. Sheet magnesium alloys offer the potential as a light weight material for use in the transportation industry due to their high specific strength and stiffness. In fact, magnesium alloys have the highest strength-to-weight ratio of all the common structural metals. Though the demand for light weight materials is present and sheet magnesium is available, the use of these materials in automotive applications has been rather limited due to high production costs and poor corrosion performance and formability. A promising process to produce wrought magnesium sheet in a more cost effective manner is Twin Roll Casting (TRC). In addition, enhanced corrosion resistance and ductility may be realized in these sheet alloys with the possible introduction of a clad layer during the TRC process thereby producing a laminate sheet where the surface properties are different from the core. The focus of this research was to investigate the potential of cladding magnesium alloy AZ31 material during the TRC process. As part of this research, a thermal fluid mathematical model of the TRC process was developed, which was then further refined to include the addition of a clad layer during the process. The TRC model was validated through experimental work conducted at the Pohang Institute of Science and Technology (POSTECH University), where TRC experiments of AZ31 were conducted under various casting conditions. The as-cast microstructure of the AZ31 sheets were characterized and measurements of the secondary dendrite arm spacing (SDAS) made at the mid-region were compared to predicted microstructures from the TRC model based on solidification history. The predicted SDAS matched with the measured values, thus, validating the model. Using the validated TRC model the feasibility of adding a clad layer was assessed and various simulations were conducted to observe the effects of cast speed, cast thickness, and clad material on the thermal history and temperature profile in both the clad and core domains. The material properties and clad thickness did not seem to impact the temperature profiles significantly, while the cast speed and initial temperature dictated whether or not the cast would be successful. Using these operational parameters a process window was created (based on the CANMET facility) to illustrate the feasibility of casting and cladding during TRC. This window is beneficial for future experimentation and understanding the effects of these casting parameters.

<p>The main goal with the master thesis has been to do a status evaluation of the chain machinery with its start chain and wire to secure the production on a short basis due to that a reconstruction is not planned at this time. An evaluation of the condition of the start chain and the rollers in the chain depository has been done. An offer has been requested for a new start chain and the evaluation of the start chains may be a basis for the decision taking. The production has been able to go on, although it has arisen some problems which have been difficult to find the causes for. There is no gathered “picture” of the machinery status and a mapping of each machinery has been compiled of comprehensive logs. Observations and measurements have also been done to prove and elucidate the biggest problems.</p><p>After the compilation a concentration has been done of the two most frequently problems during the last years, that is to say, 2006 to 2008. The work has finally fallen into suggestions for improvements of routines and suggestions for concepts for construction changes to keep a continuous stable production until a bigger reconstruction will be made.</p><p>The two problems which have been focused on were the “limit-switches” for the wires and the heat-radiation-shields situated under the tilt bridges. The arrangement for the wire problem shown to be quite simple to implement and its cause was due to that the friction was to big in the shackle, which function is to be pressed down by the wire, and thereby didn’t trigger an alarm on the computer screens.</p><p>To prevent this, lubrication was done for respective shackle to sustain the production for a short period of time. Although there have been done some concepts to sustain the production for a longer period of time.</p><p>The problems concerning the heat-radiation-shields under the tilt bridges can be solved mainly by changed maintenance routines, which have been attached in the list which has been formed.</p>

The main goal with the master thesis has been to do a status evaluation of the chain machinery with its start chain and wire to secure the production on a short basis due to that a reconstruction is not planned at this time. An evaluation of the condition of the start chain and the rollers in the chain depository has been done. An offer has been requested for a new start chain and the evaluation of the start chains may be a basis for the decision taking. The production has been able to go on, although it has arisen some problems which have been difficult to find the causes for. There is no gathered “picture” of the machinery status and a mapping of each machinery has been compiled of comprehensive logs. Observations and measurements have also been done to prove and elucidate the biggest problems. After the compilation a concentration has been done of the two most frequently problems during the last years, that is to say, 2006 to 2008. The work has finally fallen into suggestions for improvements of routines and suggestions for concepts for construction changes to keep a continuous stable production until a bigger reconstruction will be made. The two problems which have been focused on were the “limit-switches” for the wires and the heat-radiation-shields situated under the tilt bridges. The arrangement for the wire problem shown to be quite simple to implement and its cause was due to that the friction was to big in the shackle, which function is to be pressed down by the wire, and thereby didn’t trigger an alarm on the computer screens. To prevent this, lubrication was done for respective shackle to sustain the production for a short period of time. Although there have been done some concepts to sustain the production for a longer period of time. The problems concerning the heat-radiation-shields under the tilt bridges can be solved mainly by changed maintenance routines, which have been attached in the list which has been formed.

My research considers one way in which contemporary sculptural art practice might reinterpret sculpture and painting, primarily from Catholicism as represented in Italian and Spanish Renaissance and Baroque art. The themes that are explored include: faith and doubt, divinity and human nature, miracles and materials. How can sculptural practice delve into the nature of faith and doubt through materials and processes, interpretative strategies, and a consideration of contexts? Can any sense of faith or belief in the unphysical be evoked in audiences through this practice-led research? The research employs inductive means and methodologies that are fundamentally practice-led and iterative. Rather than starting with a problem-based enquiry, a careful analysis of existing artworks, primarily by the painter Michelangelo Merisi da Caravaggio and the sculptor Gian Lorenzo Bernini, was undertaken. This study has led to the production of creative work that in turn has initiated further questions and more sculptural objects. The production of sculptural artefacts creates a snowballing effect that is a self-reflective, investigative cycle. This method draws upon the sculptural process itself and takes into account external and contextual considerations. My studio-based investigations have given rise to the sculptural work. These case studies reinforce an understanding that methods that are primarily based on the assessment of haptic means relating to touch, sight and other sensory perceptions can contribute to knowledge in meaningful and unique ways. The iterative process used in this research has thematic and metaphoric parallels to the ways in which Catholic stories are retold, interpreted, and examined – narratives that have themselves been continuously readapted to suit changing contexts and intended audiences. Such narratives have been disseminated throughout the history of Christianity, and continue to be circulated in modern-day Christianity. In our post-enlightenment world, the core theme of incredulity, as imagined through art, is explored. To this end, and to make wider connections with this enquiry, philosophical writings regarding ideas of truth and subjectivity, particularly the work of Søren Kierkegaard, are investigated. The historical sculpture and painting referenced and utilised as source material are themselves reinterpretations of pre-existing narratives and stories. This research strives to explore and expose the correlative relationship that exists between understandings of past and present day contexts and employs an examination of both historical and contemporary art works and practitioners. Rather than perceiving this research project primarily in the context of other contemporary art practices, the main focus is on how European artists from the early 17th century wrestled with imagining and imaging these stories and, in that context, how the same narratives might be reinterpreted today. A selection of contemporary artists has been used throughout the research in order to help situate this work within a contemporary cultural context. The primary output from the research is a selection of three sculptural groupings, referred to as case studies, presented in chronological order, taken from the larger body of sculptural artefacts created over the course of the entire research project. The three selected case studies encapsulate the key findings and principle discoveries. The case studies are supplemented by photographs of installed site-specific work, as well as the contextual and critical analysis contained in this thesis.

The primary objective of this creative project was to fully explore and analyze the centuries old technique of lost wax casting.The secondary objective was to produce a body of work combining my creative inspirations from nature and my African culture.This body of work employed a variety of traditional metalsmithing techniques combining raised/constructed hollow ware, in a variety of metals, with cast metal forms. / Department of Art