This diploma thesis deals with bonded hybrid joints which are used for connecting parts of modern coachwork. Firstly, the thesis describes in general the process of production of the whole coachwork, from cutting of the blanks to the surface treatment including the analysis of the used materials. Subsequently, the problem of joining body parts through adhesives, but also by welding, soldering or other methods is discussed. Another part of this thesis is dedicated to an experiment in which the qualities of bonded hybrid joints were determined. Different ways of realizing the joint have been made which differed in the size of the glued surface, in the welding methods and in the process of their creation. The produced joints were tested for their strength and quality.

The content of this diploma thesis is to explore the possibility of utilization of wastes generated in the production of cement-bonded particleboards in terms of their application as secondary raw materials back into the production. At first an attention was focused on a fine-grained waste containing wood particles with cement matrix produced during the final adjustment of boards. Further, fly ash generated from the combustion of wood chips in the biomass boiler is assessed. In the theoretical part the different types of waste generated in the production of cement-bonded particleboards are characterized, including their methods of creation, production, use or disposal of the current and other proposals for utilization in the future. The research papers dealing with applications of various wastes in the production of cement composites with organic fibers were also studied. In the experimental part of the thesis the characteristics of each type of waste generated in the production of cement-bonded particleboards are evaluated using laboratory analyses and their pretreatment methods for another use are designed. Subsequently performed the laboratory verification capabilities of secondary raw materials from wastes in cement-bonded particleboards identifying and evaluating basic physico–mechanical characteristics of boards with modified composition.

The cement boards are commonly used as a filler fir or spruce chips-profit wood. The increasing demands for construction materials forcing technology to develop new types of composite materials using an alternative source of fillers. In this work in the context of theoretical knowledge about the specified fibers in composite systems are discussed properties of cement binder and filler for cement – bonded particleboards and alternative materials. The practical part describes the test methods designed recipes and then made boards of which were carved specimens intended for testing the properties of boards with alternative fillers.

This master’s thesis is divided into two parts. In the first part are these topics: bonding theory, treatment of bonding surface, types of adhesives, adhesives in the transportation industry and construction and stress of bonded joints. In the second part of this thesis is experimental evaluation of the effect of surface of material on strength of bonded joint.

The main goal of the dissertation is to design and verify coatings for surface finish of cement bonded particleboards with the aim of improvement of their resistance against the unfavorable influences of the exterior taking into account the aesthetic function of the surface finish.

<div>Polymer bonded explosives (PBXs) consist of energetic material (EM) crystals embedded inside a polymeric binder. These are highly heterogeneous structures designed to explode under controlled conditions. However, accidental ignition of PBXs leading to deflagration, or even detonation, may take place due to non-shock stimulus such as low velocity impacts and vibration. Thus, assessing the safety of PBXs under non-shock stimulus is very important.</div><div><br></div><div>The ignition in PBXs depends on several microstructural features which include mechanical properties of EM particles and polymeric binder, as well as the adhesive properties of interface between EM particles and binder. It is also sensitive to initial defects in EM particles including cracks or voids. EM particle size distribution, distance between particles and their relative location are also shown to be affecting the ignition behavior of PBXs. This study focuses on PBX composition consisting of HMX as EM and Sylgard or HTPB as polymeric binder. Among several mechanisms of hot-spot formation, this study focuses on frictional heating at cracks or debonded surfaces.</div><div><br></div><div>Finite element simulations are performed on a domain containing a single EM particle embedded inside polymer binder under compressive and tensile loading at 10 m/s. The effect of the binder properties and the particle surface properties, on damage evolution and corresponding temperature rise due to frictional heat generation, is investigated. Two binders, Sylgard and HTPB, while two surface qualities for HMX particle, low and high, are compared. The adhesion strength of the particle-polymer interface is varied and damage evolution is qualitatively compared with experimental results to estimate interfacial energy release rate for HMX-Sylgard and HMX-HTPB interfaces. Simulations of two HMX particles inside Sylgard binder, subjected to vibration loading, are performed to analyze the effect of particle-particle distance and relative location of particles on the damage evolution and frictional heating in the particles.</div><div><br></div><div>The results of impact simulations show that the low surface quality HMX particle inside HTPB is likely to propagate cracks as compared to high surface quality particle. The HMX particle inside Sylgard shows crack propagation irrespective of particle surface quality. The impact simulations with the lower stiffness binder do not show a significant increase in temperature after impact. A polymer with higher stiffness induces more particle damage under impact contributing to a larger temperature rise. Furthermore, high quality surface and higher adhesion strength induces larger stresses and increase the temperature rise. The vibration simulations show that a small particle is less likely to damage when it is shielded by a large particle irrespective of its distance, within 40-200$\mu$m, from the large particle. However, the small particle is likely to damage when it is in parallel to the large particle with respect to loading. The temperature rise in the small particle is higher than the larger particle only in case of parallel configuration. The adhesion between the particles and the polymer has a direct effect on the formation of hot-spots due to friction and through local increase of compressive stresses that may cause a surge in heat generation.</div><div><br></div><div>The energetic materials often show anisotropy in elastic and crystalline properties. Fracture in HMX along the preferred cleavage plane is considered. Anisotropy in the elastic constants is also incorporated in the fracture model. The dependence of pressure on temperature is considered using Mie-Gruneisen equation of state which is shown to be important for damage evolution in HMX at impact velocity of 100 m/s.</div>

<p>The transformation of mechanical energy into thermal energy within composite energetic materials through various thermomechanical mechanisms is thought to lead to the creation of localized areas of intense heating. The growth of these “hot spots” is responsible for the bulk reaction or decomposition of the energetic material. Understanding the formation and growth of these hot spots has been an active area of research particularly for high-speed impact and shock conditions, but further work remains to be done in particular with respect to hot spot formation due to periodic mechanical excitation. Previous literature has established that many potential thermomechanical mechanisms may act at the interface between the constituent components of a composite energetic material. In order to provide further insight and guidance into the design of safer and more resilient energetic materials, the role of adhesion on hot spot formation for polymer bonded explosives (PBXs), a subset of composite energetic materials, was explored. Single HMX (1,3,5,7-tetranitro-1,3,5,7-tetrazocane) crystals in polymer blocks were subjected to ultrasonic excitation and subsequent heating was captured via infrared thermography. Subsequent testing of HMX PBXs using a drop weight tower captured changes in the sensitivity of the energetic material. Variation of the polymer binder allowed for a range of adhesive and mechanical properties to be examined. These experiments on the role of adhesion under these kinds of excitations provided insight into how mechanical energy is being transformed into localized heating.</p>

When operating hydraulic mining excavators the loading equipment is exposed to harsh conditions which lead to extensive wear of the equipment, especially the bucket and bucket teeth. Simulations are used to better understand the wear development and to evaluate new methods to operate excavators more efficiently. At the Aitik mine, operated by the high-tech metal company Boliden Mines, hydraulic excavators are used when loading the mined ore. One of the hydraulic excavators used at Aitik is the Komatsu PC7000. In this master thesis, a simulation model for the hydraulic excavator Komatsu PC7000 was developed with the simulation software LS-DYNA. This model consists of multi rigid body dynamics to describe the motion of the excavator and a granular material model to describe the rocks loaded into the bucket of the excavator. Simulations with two different types of granular material models have been utilized to study the wear development of the bucket. One of the models (bonded DE model) uses bonded discrete elements to describe the large rocks and single discrete elements are used to describe smaller rocks. This model is compared to the current FE-DE model which is being used today at Boliden. This model uses finite elements (FE) to model the larger rocks and discrete element spheres (DES) for smaller rocks. By using the bonded DE method a 71\% reduction in simulation time could be achieved. This can be partly explained by the reduction of the number of elements included in the rock pile.  Archard's wear law was used to numerically describe the wear development of the bucket. When simulating the wear a total of 30 bucket fillings were performed with the excavator. This was done with both the bonded DE method and the FE-DE method. In this wear study, the inside of the bucket was of interest. The resulting simulated wear map was compared to experimental measurements from which the plate thickness of the bucket had been measured two times to obtain the wear depth of some points inside the bucket. The experimental measurements and two 3D scanned point clouds were used to determine the wear depth inside the bucket. Results from the simulation showed that the wear is concentrated to the center of the bucket while less wear is concentrated to the sides of the bucket. With the bonded DE method the wear appeared to be more evenly distributed inside the bucket while the wear from the FE-DE method appeared in spots inside the bucket. The experimental results also showed that the wear was more extensive in the center of the bucket and also in the back of the bucket. Both simulation methods also showed that the wear was concentrated to the back of the bucket. From the simulations, it was also seen that the behavior of the material flow differed between the two methods. In the bonded DE method the material flow had more sliding behavior while the material flow in the FE-DE method had more rolling behavior. This could also be the reason why the bonded DE method captures the wear more evenly. The rolling behavior seen in the FE-DE method leads to more impact wear which is not captured by Archard's wear law. Overall, the bonded DE method leads to a big reduction in simulation time which is favorable when it comes to simulation. The larger rocks will have simpler shapes without sharp corners. However, the method allows for a more complex shape than just an ordinary sphere which is the simplest and most common shape to describe granular material. The bonded DE method also allows for easier configuration of contact definition since fewer contact interfaces must be added to the model. Furthermore, the post-processing of wear in LS-DYNA was facilitated since the wear does not have to be divided into two wear collectors for FE elements and DE elements.

The body of information concerning carbon-carbon spin-spin coupling constants now includes a large number of coupling constants, the establishment of a dihedral angular dependence on 3JCC, and the application of 3JCC to conformational analysis. This study adds another dimension to the growing wealth of information associated with 13 C-NMR: the influence of some non-bonded interactions on 3JCC Four types of non-bonded interactions that could influence vicinal carbon-carbon NMR coupling constants were investigated. To facilitate the NMR studies, a variety of 13C-labeled compounds were synthesized.

The discovery of carbon nanotubes in 1990s popularized a new area of research in materials science called Nanoscience. In the following decades, several carbon based nanoparticles were discovered or engineered and with the discovery of Graphene nanoplatelets (GNP) in 2010, carbon based nanoparticles were propelled as the most promising class of nanoparticles. High mechanical strength and stiffness, excellent electrical and thermal conductivity, and high strength to weight ratios are some of the unique abilities of CNTs and GNPs which allow their use in a wide array of applications from aerospace materials to electronic devices. In the current work presented herein, CNTs and GNPs are added to polymeric materials to create a nanocomposite material. The effects of this nanoparticle addition (a.k.a reinforcement) on the mechanical properties of the nanocomposite polymer materials are studied. Specifically, efforts are focused on studying fracture toughness, a material property that describes the material's ability to resist crack growth. Relative to the conventional metals used in structures, epoxy-based composites have poor fracture toughness. This has long been a weak link when using epoxy composites for structural applications and therefore several efforts are being made to improve their fracture toughness. In the first, second and third chapters, the enhancement of fracture toughness brought about by the addition of carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) was investigated. CNT-Epoxy and GNP-Epoxy Compact Tension (CT) samples were fabricated with 0.1% and 0.5% nanofiller weight concentrations. The potential synergistic effects of dual nanofiller reinforcements were also explored using CNT/GNP-Epoxy CT samples at a 1:3, 3:1 and 1:1 ratio of CNT:GNP. Displacement controlled CT tests were conducted according to ASTM D5045 test procedure and the critical stress intensity factor, $K_{IC}$, and the critical fracture energy, $G_{IC}$, were calculated for all the material systems. Significant enhancements relative to neat epoxy were observed in reinforced epoxies. Fracture surfaces were analyzed via scanning electron microscopy. Instances of CNT pullouts on the fracture surface were observed, indicating the occurrence of crack bridging. Furthermore, increased surface roughness, an indicator of crack deflection, was observed along with some crack bifurcations in the GNP-Epoxy samples. In the fourth chapter of Part I, the influence of pre-crack characteristics on the Mode-I fracture toughness of epoxy is investigated. Pre-crack characteristics such as pre-crack length, crack front shape, crack thickness and crack plane profile are evaluated and their influence on the peak load, fracture displacement, and the critical stress intensity factor, $K_{IC}$ is studied. A new method of razor blade tapping was used, which utilized a guillotine-style razor tapping device to initiate the pre-crack and through-thickness compression to arrest it. A new approach of quantitatively characterizing the crack front shape using a two-parameter function is introduced. Surface features present on the pre-crack surface are classified and their effects on the post crack initiation behavior of the sample are analyzed. This study aims to identify and increase the understanding of the various factors that cause variation in the fracture toughness data of polymeric materials, thus leading to more informed engineering design decisions and evaluations. Chapters six and seven of Part II investigate the SHM capabilities of dispersed MWCNTs in mock, inert, and active energetics. In these experimental investigations, the strain and damage sensing abilities of multi-walled carbon nanotube (MWCNT) networks embedded in the binder phase of polymer bonded energetics (PBEs) are evaluated. PBEs are a special class of particulate composite materials that consist of energetic crystals bound by a polymer matrix, wherein the polymer matrix serves to diminish the sensitivity of the energetic phase to accidental mechanical stimuli. The structural health monitoring (SHM) approach presented in this work exploits the piezoresistive properties of the distributed MWCNT networks. Major challenges faced during such implementation include the low binder concentrations of PBEs, presence of conductive/non-conductive particulate phases, high degree of heterogeneity in the PBE microstructure, and achieving the optimal MWCNT dispersion. In chapter seven, Ammonium Perchlorate (AP) crystals as the oxidizer, Aluminum grains as the metallic fuel, and Polydimethylsiloxane (PDMS) as the binder are used as the constituents for fabricating PBEs. To study the effect of each constituent on the MWCNT network's SHM abilities, various materials systems are comprehensively studied: MWCNT/PDMS (nBinder) materials are first evaluated to study the binder's electromechanical response, followed by AP/MWCNT/PDMS (inert nPBE) to assess the impact of AP addition, and finally, AP/AL/MWCNT/PDMS (active nPBE-AL) to evaluate the impact of adding conductive aluminum grains. Compression samples (ASTM D695) were fabricated and subjected to monotonic compression. Electrical resistance is recorded in conjunction with the mechanical test via an LCR meter. Gauge factors relating the change in normalized resistance to applied strain are calculated to quantify the electromechanical response. MWCNT dispersions, and mechanical failure modes are analyzed via scanning electron microscopy (SEM) imaging of the fracture surfaces. Correlations between the electrical behavior in response to the mechanical behavior are presented, and possible mechanisms that influence the electromechanical behavior are discussed. The results presented herein demonstrate the successful ability of MWCNT networks as structural health monitoring sensors capable of real-time strain and damage assessment of polymer bonded energetics. / Doctor of Philosophy / The discovery of carbon nanotubes in 1990s popularized a new area of research in materials science called Nanoscience. Carbon nanotubes (CNTs) are one of several forms of Carbon, meaning a differently structured carbon molecule in the same physical state similar to diamonds, graphite, and coal. In the following decades, several carbon based nanoparticles were discovered or engineered and with the discovery of Graphene (GNP) in 2010, carbon based nanoparticles were propelled as the most promising class of nanoparticles. High mechanical strength and stiffness, excellent electrical and thermal conductivity, and high strength to weight ratios are some of the unique abilities of CNTs and GNPs which allow their use in a wide array of applications from aerospace materials to electronic devices. In the current work presented herein, CNTs and GNPs are added to polymeric materials to create a nanocomposite material, where the term "composite" refers to a material prepared with two or more constituent materials. The effects of this nanoparticle addition (a.k.a reinforcement) on the mechanical properties of the nanocomposite polymer materials are studied. Specifically, efforts are focused on studying fracture toughness, a material property that describes the material's ability to resist crack growth. Fracture toughness is a critical material property often associated with material and structural failures, and as such it is very important for safe and reliable engineering design of structures, components, and materials. Moving from a single function (i.e. mechanical enhancement) to a more multi-functional role, taking advantage of the excellent electrical and mechanical abilities of CNTs, a structural health monitoring system is developed for use in polymer bonded energetics (eg. solid rocket propellants). When a material undergoes mechanical deformation or damage, the measured electrical properties of the material undergo some change as well. Using sensor networks built with multiple CNTs dispersed within a polymeric material, a whole structure can be made into an effective sensor where by simply monitoring the electrical properties, the extent of material deformation and damage can be known. Such a system is geared towards providing early warning of impending catastrophic material failures thus directly improving the safety during material handling and operations.