This master thesis has its main focus within embossing operations and how different factors influence the result. The work was performed at Stora Enso Research Centre in Karlstad, Sweden. Embossing is relatively complex operation to analyze since the paperboard can be exposed of both bending, shear and compression at the same time. The techniques used today for evaluating embossing on paperboard consist of experimental setups. These experimental techniques needed to be complemented in order to simplify the approach for embossing evaluations. The aim of this thesis was to develop a simulation material model, created with Finite Element Method by using Abaqus (2014), which capture the experimental behavior of embossed paperboard. The goals were to understand which material properties that are of high importance in embossing operations, and how sensitive the simulation material model is at small geometry changes of the embossing tool. A three dimensional finite element material model has been created in Abaqus (2014). The analysis was performed as dynamic quasi-static where an implicit solver was used. The simulation material model consisted of a continuum model, which describes the behavior of the plies, and an interface model implemented as cohesive elements, which describes the inelastic delamination between the plies. The continuum model was defined as an anisotropic linear elastic-plastic material model with isotropic linear hardening together with Hill´s yield criterion. The interface model was defined with an anisotropic elastic-plastic traction-separation law and an exponential damage evolution model. The purpose of the experimental tests was to capture the behavior of embossed paperboard and the goal was then to recreate the behavior in the simulation model. The results in this thesis focus on the relationship between the applied force and the displacement. An experimental and numerical study of out-of-plane compression has also been conducted, where the aim was to determine the out-of-plane elastic modulus, EZD. According to embossing results, the embossing results showed an exponential hardening behavior while the numerical results, unfortunately, showed a declining hardening behavior. Despite this, some understanding regarding which parameters that are of utmost importance have been achieved. The material parameters which had the highest influence on embossed paperboards seem to be the out-of-plane shear properties. This thesis also shows that the material model is sensitive of small changes of the tool geometry. The proportion of shear, bending and compression are strongly dependent on if the tool has sharp edges or if the edges are more rounded.

The goal of this research is to develop an integrated polymer embossing module, with which difficult-to-emboss polymer microstructures and microparts can be fabricated in a cost-effective manner. In particular, the research addresses three major limitations of the hot embossing process, namely, long cycle time, difficulty in producing shell patterns, and difficulty in building up a high embossing pressure on thick substrates. To overcome these limitations, three new technical approaches two-station embossing, rubber-assisted embossing, and through-thickness embossing were developed and investigated. Fundamental understanding of these new embossing techniques were achieved through extensive experimental and theoretical studies involving parametric experiments, rheological characterization, surface investigation, mathematical modeling, and computer simulation.

Master of Science / Department of Architectural Engineering and Construction Science / Sutton F. Stephens / Cold-formed steel studs, though they are a relatively new building material, have become a mainstay in modern construction. They are favored over traditional lumber studs for their high strength to weight ratio and resistance to insects and rot. Due to their relative newness as a material, new advances in their design and implementation are being developed quite rapidly. One such advancement is flange embossing, a technique used to increase the strength of the connection of screws into the studs. Currently, embossed flanges are not specifically addressed in the North American Specification for the Design of Cold-Formed Steel Structural Members (AISI S100), thereby preventing current design equations from being used to calculate an embossed stud's member properties. An experimental investigation was undertaken to determine what effect, if any, flange embossing has on the nominal flexural strength of cold-formed steel studs as determined using the provisions of AISI S100-07. Studs with embossed flanges were tested in bending and their actual flexural strength was computed. This data was then compared with the nominal flexural strength determined using the AISI Specification, without embossing, to determine if these equations would still be appropriate for the design of embossed studs.

This report demonstrates a UV-embossed polymeric chip for protein separation and identification by Capillary Isoelectric Focusing (CIEF) and Matrix Assisted Laser Desportion/Ionization Mass Spectrometry (MALDI-MS). The polymeric chip has been fabricated by UV-embossing technique with high throughput; the issues in the fabrication have been addressed. In order to achieve high sensitivity of mass detection, five different types of UV curable polymer have been used as sample support to perform protein ionization in Mass Spectrometry (MS); the best results is compared to PMMA, which was the commonly used plastic chip for biomolecular separation. Experimental results show that signal from polyester is 12 times better than that of PMMA in terms of detection sensitivity. Finally, polyester chip is utilized to carry out CIEF to separate proteins, followed by MS identification. / Singapore-MIT Alliance (SMA)

This study presents a new process to fabricate gapless triangular micro-lens array (GTMA). The process includes optical simulation with tracepro, UV lithography, photoresist reflow process, Ni electroplating and hot embossing technique. After photoresist triangular column array is defined using UV lithography, reflow process is applied to melt photoresist triangular column array into the shape of triangular micro-lens array. With this reflowed triangular micro-lens array, Ni is deposited and covered uniformly on the triangular micro-lens array using electroplating. The growth rate of Ni is controlled at electroplating current density of 1 Ampere Square Decimeter (ASD; A/dm2). After this electroplating process is finished, a mold of GTMA is obtained, which is served as primary mold. Subsequently, with passivation technique applied on this mold¡¦s surface, electroplating process is applied again to obtain a secondary mold. Next, this secondary mold is served as master for the subsequent hot embossing process to replicate the GTMA pattern onto polymeric material PMMA and PET sheet. The mold with stiffness and hardness plays an important role in GTMA hot embossing process. In addition, this GTMA used as optical film can offer a 100 % fill factor and a simulation of optical coupling efficiency of 66.7% to improve luminance of backlight module (BLM). In addition, this study presents the fabricated molds of GTMA with different aspect-ratio about 0.109 and 0.133. The optical measurement of BLM shows that this optical film of GTMA pattern with aspect-ratio about 0.109 can increase 15.1% of luminance and with aspect-ratio about 0.133 can increase 22.1% of luminance.

Light emitting diode (LED) will have development in liquid crystal display (LCD) backlight. Nevertheless, the point source of LED is not suitable for large size panel. Therefore, this research will change the package which is bullet type and design gapless dual-curvature micro lens (GDML). Using the optics software TracePro is simulation luminance to compare of hexagon, triangular and dual-curvature micro lens, and fabrication of the better size. We can get metal model using micro-electro-mechanical systems (MEMS) technology after electroforming and hot embossing. The micro lens is formed by UV cure in metal model. It has different curvature and fill factor 100%. The advantage of electroforming is can manufacture a lot of product fast with high performance. The shrinkage rate is less than 0.5%. The collocation package of micro lens and LED chip can improve intensity and uniformity.

In this dissertation work, a constant temperature embossing process was developed and investigated. By softening and crystallizing a supercooled polymer at the same temperature, the embossing and solidification stages can be carried out isothermally without thermal cycling. The new process was demonstrated for replicating rectangular trenches with different aspect ratio for two different polymers PET and PEEK. The raw materials were characterized for their thermal and rheological properties to determine the processing parameters. The polymers were also characterized by a modified tensile testing apparatus to determine the tensile properties of the film during embossing. The processing parameters including embossing temperature, embossing pressure and embossing time were varied based on the material properties and optimized. A semi-empirical model was established to correlate the crystallizing kinetics of the materials to the change in rheological properties during embossing. The model was used as a tool to predict the rheological properties of the polymer at conditions where experimental determination is difficult. Finally, embossing simulations with the semi-empirical rheological model were conducted to study the unique process dynamics of constant-temperature embossing and verify some experimental findings. Different cases of constant-temperature embossing involving low to high rates of crystallization were simulated and compared with the conventional embossing process. Based on the experimental and simulation results, processing strategies for constant-temperature embossing were devised.

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This paper describes a promising fabrication technique for rapid replication of high aspect ratio microstructured molds for UV embossing. The process involves casting silicone rubber on a microstructured master, replicating an epoxy mold using the PDMS rubber mold and finally, metallizing the surfaces of the epoxy mold by electroless plating nickel (EN). The preliminary study suggests that this technique is feasible for rapid replication of high aspect ratio molds for UV embossing. Uniform molds can be replicated rapidly through this technique making the process economical and accessible. / Singapore-MIT Alliance (SMA)

This experiment produces a new flexible heat pipe, and further tests and explores its characteristics and performance. The heat pipe is made of silicone rubber, a kind of polymer material, and was molded by hot embossing. Characteristics of this material include good bending resistance, lightness, and good resistance to high temperature. Furthermore, copper sheets connected with silicone were placed at the evaporator section and condenser section to enhance heat transfer effects. DI water in the pipe was used as the working medium, and two-layer 250 mesh copper nets were used as a wick to strengthen the heat pipe¡¦s capillary effects. The researcher set the vacuum degree at 0.0658 atm to test the pipe¡¦s performances at different powers. Key findings include an optimum filling ratio of 40%, and a largest heat flux of 11.75 W/cm2 during the proficiency test. In addition to the proficiency test . The influence of different angles of bends (0 ~ -90¢X) on the pipe¡¦s heat transfer performance was also tested and based on heat thermal resistance obtained, found that the best bended angle of the flexible heat pipe was -15¢X, and thermal resistance will increase with the angle(-30 ~ -90¢X). The experiment proves a small angle bend that is helpful for the working medium to flow back to the evaporator section, but the heat transfer performance would shrink because the wick could not affix to the inner wall of the pipe if the angle is too large. This work shows the proper combination of pipe parameters will significantly improve heat transfer performance.