Metallic glasses (MGs) are very attractive for structural applications due to their large elastic strain, high strength and hardness, resulting from their unique atomic structure. However, MGs are brittle. Preparing metallic glass–crystal composites (MGCCs) from parent glass through thermal treatment is a useful method to induce ductility and work hardening. Thus, besides the direct applications of as-prepared MGs, the glasses can be used as a starting material to be processed, for example, by thermoplastic forming or thermal treatment to design components with desired shape and/or properties. In this view, it is of high importance to know the phase- transformation mechanisms and kinetics upon heating MGs, especially for rapid heating, which has not been sufficiently studied yet. CuZrAl-based alloys, with near CuZr equimolar compositions, are suitable for producing MGCCs with improved plasticity owing to their good glass-forming ability and the formation of ductile B2 CuZr phase upon crystallization. However, the crystallization mechanism(s) and products have mainly been elucidated by extrapolating the available knowledge of the binary CuZr system. In the present work, a set of complementary techniques including resistive (Joule) heating, in situ high-energy synchrotron X-ray diffraction, conventional and ultrafast differential scanning calorimetry and containerless solidification during electromagnetic levitation is used to map the phase evolution ― crystallization and solid-state phase transformations ― in Cu₄₇.₅Zr₄₇.₅Al₅, Cu₄₇.₅Zr₄₈Al₄Co₀.₅ and Cu₄₆.₅Zr₄₈Al₄Nb₁.₅ MGs during isokinetic and isothermal annealing. The resistive heating devices, custom-built at the Leibniz Institute for Solid State and Materials Research Dresden – IFW Dresden, enable heating rates Φ to range from 10¹ up to 10⁵ K s⁻¹ in a vacuum. Using the obtained experimental data, continuous-heating-transformation (CHT) diagrams for a heating rate range exceeding six orders of magnitude, covering the entire supercooled liquid region, and time-temperature-transformation (TTT) diagrams are constructed. The transformation maps reveal the competition between the Cu₁₀Zr₇, B2 CuZr and τ4 (Cu₂ZrAl) phases during crystallization. The formation of the primary phase and transformation sequence depends on the MG composition as well as on the heating rate. The critical heating rate to bypass the crystallization increases from ~30 000 K s⁻¹ for Cu₄₇.₅Zr₄₇.₅Al₅ MG to ~40 000 K s⁻¹ for Cu₄₆.₅Zr₄₈Al₄Nb₁.₅ MG and to ~90 000 K s⁻¹ for Cu₄₇.₅Zr₄₈Al₄Co₀.₅ MG, reflecting their glass-forming ability. The optimum heating rate to obtain glass–crystal composites with the predominant and desired B2 CuZr phase is evaluated to be Φ > 1 000 K s⁻¹ for Cu₄₇.₅Zr₄₇.₅Al₅ MG, Φ > 1 500 K s⁻¹ for Cu₄₇.₅Zr₄₈Al₄Co₀.₅ MG, and Φ > 4 000 K s⁻¹ for Cu₄₆.₅Zr₄₈Al₄Nb₁.₅ MG. Cu₄₆.₅Zr₄₈Al₄Nb₁.₅ MG shows an increased propensity for the formation of brittle Cu₁₀Zr₇ intermetallic phase, compared to Cu₄₇.₅Zr₄₇.₅Al₅ and Cu₄₇.₅Zr₄₈Al₄Co₀.₅ MGs. The TTT diagram for the isothermal heating of Cu₄₆.₅Zr₄₈Al₄Nb₁.₅ shows an apparent double-nose shape which corresponds to the primary crystallization of Cu₁₀Zr₇ at lower temperatures and B2 CuZr at higher temperatures.

The flexural behavior of a light-weight wood-based composite system was studied through destructive experiments. The composite panel system consisted of profiled dimensional lumber, which makes up the surface layers, and 1"-thick boards running across the surface layers. Considering the changes in cross-sections along the panel due to the presence of the embedded boards, classical theories such as the Euler-Bernoulli beam and Kirchhoff-Love plate could not be implemented. Instead, the deflections and maximum failure loads of the composite system under full- and short-span bending tests were measured during their destructive bending testing, and were compared against the mechanical properties of the conventional three-ply CLT panel with the same thickness as the panel with embedded cross-laminations. According to maximum failure loads and deflections, it was concluded that full-span panels with embedded cross-laminations exhibited higher strength and stiffness, whereas short-span panels exhibited higher strength and lower stiffness properties compared to conventional CLT panels.

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<p>This work is an experimental approach to understand the effect of the microstructure on large strain deformation behavior of A356 alloy (with various additions of titanium and strontium) under uniaxial tensile, compressive and V-bend loading conditions. The studies were carried out on unmodified and Sr-modified A356 Al alloy, where Sr was added to refine the morphology of the eutectic Si phase particles. The two variants were then used to study the effect of size and shape distributions of Si eutectic phase particles within the material on the deformation behavior under uniaxial tension, compression and V-bending conditions. The alloy with a modified and refined eutectic Si phase particles showed significant improvement in ductility and bendability, whereas the differences in compression were not appreciable. In addition to Sr addition, Ti was also added as a grain refiner to the alloys at three different levels to obtain microstructures with different grain sizes. The results in the form of full field strain maps show that the larger grained alloy exhibits extensive strain inhomogeneity, whereas the grain refined alloy shows a more homogenous loading pattern.</p> / Master of Applied Science (MASc)

This thesis seeks to establish whether recycled E-waste rABS from Stena Recycling AB in Halmstad, Sweden, can be effectively utilized in additive manufacturing processes and if it can be applied similarly to virgin ABS. Results show that it is possible to apply the rABS granules on 3D-printing but with mechanical property losses and cosmetic losses. The result shows a loss in tensile strength between rABS and virgin ABS.The difference of the best performing rABS versus the best performing virgin ABS results in a mean loss of 32% and best performing loss of 25%. The research is confined to filament extrusion and experiments were conducted in FabLab Halmstad utilizing 3Devo Composer with 15 different temperature settings. The filament was then used in Prusa MK4 where three tensile tests in 0, 45 and 90 degrees with 5 iterations per test and per setting. The 3D-printed recycled tensile tests results are compared to tensile tests made from virgin ABS. The conclusion is that there are significant mechanical property losses  and with poor printability compared to store bought ABS filament.

Mechanical Response Tissue Analysis (MRTA) is an emerging technology for assessing maximal bending stiffness (EI) of human long bones in vivo. The MRTA variable, EI, is the product of Young's modulus of elasticity (E) and cross-sectional moment of inertia (I). EI quantifies material and architectural/geometric properties of bone. Published human research using MRTA to measure EI has been limited to the ulna; however, the tibia requires further investigation due to its central involvement in many human activities and exercise-related clinical problems, e.g. stress fracture of the lower leg. To evaluate the inter- and intra-reliability of tibial EI, 22 healthy women (X + SD: 20.8 + 1.8 yr) were assessed twice daily for three non-consecutive days. Each daily session consisted of five repeated trials. The ulnar EI protocol of McCabe et al. [J Bone and Mineral Res. 1991;6(1):53-59] was adapted to assess tibial EI via MRTA. A significant difference was not found in scores for five repeated trials taken consecutively on the same day. Mean scores for EI were higher on day 1 (59.1 &#177; 35.5 N&#183;m², p < 0.05), compared to day 2 (46.9 &#177; 22.3) and day 3 (49.9 &#177; 18.3). Individual trial mean scores for EI on each day (mean of 5 trials) were highly correlated, R² = 0.84, 0.62, and 0.79 (set 1 vs. 2, for day 1,2,3, respectively) and the average percent change between sets 1 and 2 on each day was 5.3. The inter-test (between day) reproducibility was found to be low and unacceptable, 11.7, 18.3, and 1.3%, for day 1 vs. 2, 1 vs. 3, and 2 vs. 3. Poor inter-day reliability may be a result of the inability, at the time of this study, to apply the best computational EI model. It is concluded that tibial bone stiffness measurements with the MRTA are in the range of acceptability for same day inter- and intra-trial reliability when the 7-parameter analytic model of vibratory properties developed by McCabe et al. is used. / Master of Science

The design and construction of roads with longer service lives is a priority of civil engineers. The selection of appropriate highway materials with respect to climatic and loading conditions may significantly increase the lifespan of pavements. One material receiving interest in the area of improved roadway performance is polymer-modified binder. The complex behavior of polymer-modified binders, particularly over time, is not yet well-understood by engineers. Therefore, an experimental study was performed to determine the effects of four years of storage at room temperatures (23°C) on the dynamic mechanical properties of polymer-modified binders at intermediate and high temperatures. A typical paving grade (AC-20) and three elastomeric modifiers, each at three concentrations were used. Initial tests were performed in 1995 to evaluate the effects of short-term aging as simulated by the Rolling Thin Film Oven Test (RTFOT) procedure. This study encompasses a second phase of testing occurring after the modified binders were stored at ambient room temperature (23°C) for four years. The study found that significant changes affecting the dynamic response of binders occur during long term storage at a temperature of 23°C. These changes are dependent on the type and concentration of modifier and may be beneficial. Additionally, four mathematical models describing the dynamic response of binders were evaluated and found to be variable in their ability to accurately predict response of modified binders. Most of these models are not well suited for prediction of the response of stored binders. / Master of Science