<p>A procedure for calibrating a discrete element (DE) computational soil model for various moisture contents using a conventional Asperity-Spring friction modeling technique is presented in this thesis. The procedure is based on the outcomes of two physical soil experiments:</p> <p>(1) Compression and (2) unconfined shear strength at various levels of normal stress and normal pre-stress. The Compression test is used to calibrate the DE soil plastic strain and elastic strain as a function of Compressive stress. To calibrate the DE inter-particle friction coefficient and adhesion stress as a function of soil plastic strain, the unconfined shear test is used. This thesis describes the experimental test devices and test procedures used to perform the physical terramechanical experiments. The calibration procedure for the DE soil model is demonstrated in this thesis using two types of soil: sand-silt (2NS Sand) and silt-clay(Fine Grain Soil) over 5 different moisture contents: 0%, 4%, 8%, 12%, and 16%. The DE based models response are then validated by comparing them to experimental pressure-sinkage results for circular disks and cones for those two types of soil over 5 different moisture contents. The Mean Absolute  Percentage Error (MAPE) during the compression calibration was 26.9% whereas during the unconfined shear calibration, the MAPE was calculated to be 11.38%. Hence, the overall MAPE was calculated to be 19.34% for the entire calibration phase.</p>

The objective of this thesis is to generate and enhance technical specifications for mooring equipment designated for the Swedish Navy, as commissioned by the Swedish Defence Materiel Administration. The technical specifications will primarily emphasize the capacity to endure various load scenarios imposed by the Swedish Defence on the mooring equipment. This technical report constitutes a preliminary investigation in collecting technical requirements where the mechanical characteristics will be of focus. The investigation assessed the elasticity characteristics of mooring ropes, considering their dependence on length and loading rate. As the mooring ropes are exposed to large forces and environmental circumstances, this study focused on investigating the impact of a used and worn rope, with the conclusive finding that the worn rope exhibited a substantial decline in its strength characteristics.  The thesis work will examine the different load cases, encompassing both slow and shock loadings, with the result that Young's modulus does depend on the loading rate and that the magnitude of damping in the rope holds notable significance. The mooring goods must also endure extreme conditions without failing prematurely while still conforming to the performance requirements of the personnel handling the ropes. Therefore, a study is included regarding how much impact the weather conditions may have on the mooring ropes and which parameters are important. The thesis also outlines the importance of considering similar handling standards for new mooring goods, given the expectation of future procurement. It is crucial to avoid certain mistakes during handling, which can severely damage personnel and equipment. Therefore, it is necessary to ensure that the new mooring ropes meet the current handling standards to maintain safety and avoid costly accidents. This report emphasizes the significance of adhering to proper handling standards in procuring and deploying mooring goods for the Swedish marine. / Syftet med detta arbete är att utveckla samt förbättra de tekniska specifikationer som FMV idag besitter angående de tampar \&amp; förtöjningsgods som är avsedda för den svenska flottan, på uppdrag av Försvarets Materielverk, FMV. Denna rapport är en förstudie för samlandet av tekniska krav där fokuset främst ligger på de mekaniska egenskaperna ur ett hållfasthetsmässigt perspektiv. Undersökningen bedömde elasticitetsegenskaperna hos förtöjningsrep med hänsyn till deras beroende av längd och belastningshastighet. Eftersom dessa förtöjningsrep utsätts av diverse stora krafter och miljöförhållanden så undersöktes även vilken påverkan detta har på repen. Detta undersöktes genom att jämföra ett nytt mot ett gammalt och slitet rep. Båda av samma modell och tillverkare. Denna jämförelse ledde till slutsatsen att det använda repet besatt en betydande nedgång i samtliga sina egenskaper ur ett förtöjningsperspektiv. Avhandlingen kommer undersöka repens, främst amfibiebataljonens, olika belastningssituationer, inklusive både långsamma och plötsliga belastningar för att utvärdera de olika lastfallen de kan tänkas utsättas för. Detta resulterade i att elasticitetsmodulen verkar ha ett beroende av lastningshastigheten och visar på viskoelastiska egenskaper samt att dämpningsfaktorn har en betydande storlek hos tampen. Förtöjningsutrustningen måste även klara en rad olika miljöförhållanden utan att plötsligt ge vika, samtidigt som de uppfyller prestandakraven hos besättningen. Därför följer även en utredning kring hur mycket väderförhållandena kan påverka repen samt vilka parametrar som är viktiga att ta hänsyn till. Rapporten syftar även till att betona vikten av standardisering för ny förtöjningsutrustning med tanke på eventuell framtida upphandling. Det kan vara avgörande att undvika misstag vid hantering, vilket kan resultera i skador på besättning och utrustning. Därför är det viktigt att se till att nya förtöjningsrep uppfyller och upprätthåller de aktuella standarder som finns.

In an effort to increase the fuel efficiency of cars more widespread use of higher strength steels is seen for their high strength-to-weight ratio. Thesesteels are more limited in their formability and tendency to harden than conventional steels, complicating manufacturing. This thesis summarizes the available research on resistance projection nut welding to higher strength steels and investigates the accuracy of the simulation program SORPAS when simulating projection nut welds to AlSi-coated Boron steel. It was found that the greatest difficulties in welding coated ultra high strength steels were the metallurgical effects of both the high alloying content of the steel and the coatings interacting with the weld when melting. Although SORPAS was an intuitive program to use for resistance welding and had a wide library of materials available, it was not found to be able to predict the resistance characteristics or results of projection nut welds to coated Boron steel without significant changes to default material parameters. The biggest issue was the delaying effect the coating layer had on the peak resistance, something not observed experimentally. Better results are suggested to be possible after experimentally ensuring the properties of the materials used and importing those values into SORPAS. / I ett försök att öka bilars bränsleeffektivitet används i allt större utsträckning stål med högre hållfasthet på grund av deras goda förhållande mellan styrka och vikt. Dessa stål är mer begränsade i sin formbarhet och tendens att härda än konventionella stål, vilket försvårar tillverkning. Denna uppsats sammanfattar den tillgängliga forskningen om motståndssvetsning med projektionsmutter i höghållfasta stål och undersöker noggrannheten hos simuleringsprogrammet SORPAS vid simulering av projektionsmuttersvetsar i AlSi-belagt borstål. Det konstaterades att de största svårigheterna vid svetsning av belagda ultrahöghållfasta stål var de metallurgiska effekterna av både stålets höga legeringsinnehåll och beläggningarnas interaktion med svetsen vid smältning. Trots att SORPAS var ett intuitivt program att använda för motståndssvetsning och hade ett brett bibliotek av tillgängliga material kunde det inte förutsäga motståndsegenskaperna eller resultaten av projektionsmuttersvetsar mot belagt borstål utan betydande förändringar av standardmaterialparametrarna. Det största problemet var den fördröjande effekt som beläggningsskiktet hade på maximala resistansen, något som inte observerades experimentellt. Bättre överenstämmelse föreslås vara möjlig efter att experimentellt säkerställa egenskaperna hos de material som används och importera dessa värden till SORPAS.

<p>Subcutaneous injection through devices such as autoinjectors is a preferred delivery method for wide array of pharmaceuticals such as monoclonal antibodies. Needle insertion during drug delivery involves large deformation, damage, and fracture of the skin tissue and affects drug transport and uptake. Yet, our understanding of needle insertion biomechanics is limited, but is crucially important to create autoinjectors that lead to the least amount of pain, penetrate the skin to a desired depth, produce small lesions that minimize back flow of drug, and operate robustly even given the variability in the skin mechanics among individuals. Computational models of needle insertion lends itself as an excellent avenue for studying the biomechanics of injector- skin interactions and for proposing better device designs. This work is focused on introducing a comprehensive computational modeling framework for optimizing needle insertion by autoinjector devices, while addressing limitations in experimental data and constitutive modeling of damage and fracture mechanisms in skin</p>

<p dir="ltr">Energetic materials (EMs) manufacturing practices have evolved little since the First and Second World Wars. Because of this, a substantial focus has recently been placed on modernizing the processes used in the production of these materials to mitigate the risk of human error and prevent the potentially fatal, and costly, consequences that exist when accidents take place. In this work, a piezoelectrically actuated inkjet printer system was used to deposit functional materials onto the surfaces of mock and live polymer-bonded EMs. The benefit to this is two-fold: (1) the material can safely be deposited remotely, %mention human error? and (2) this high resolution method of printing can open the door to novel applications, allowing for functional elements to be integrated directly with the material. To start, composite formulation and mixing parameters were studied on a variety of mixers to better inform substrate preparation and the role that these parameters may play in a variety of substrate material properties, including local internal composition, density, quasi-static compression, and surface topography. From here, the topography and surface free energy of the surface of these materials was analyzed further to better inform ink formulation and selection. Upon observing the ink behavior at the interface, print parameters were chosen that supported the creation of continuous architectures that could function in a variety of capacities, including as resistance probes, strain gauges, heaters, spark gap igniters, and antennas.</p>

<p>Carbon fiber bending during Carbon Fiber Reinforced Plastic (CFRP) milling is an important factor on the quality of the machined surface. When the milling tool rotates, the fiber first contacts the rake face instead of the tool edge at a certain cutting angle, then the fiber is bent instead of being cut by the tool. It causes the matrix and the fiber to fall out, and the fiber is broken from deep inside the machined surface. The broken fibers are pulled out as the tool rotates, which is known as pull-out fibers. The machining defect is the main cause of deteriorating the quality of the machined surface. To reduce such machining defects, it is important to predict the carbon fiber bending during CFRP milling. However, it is difficult to determine a point where fiber bending occurs because the fiber cutting angle changes every moment as the tool rotates. Therefore, in this study, CFRP milling simulation was performed to numerically analyze the machining parameters such as fiber cutting angle, fiber length, and the magnitude of fiber bending according to the different milling conditions. In addition, the deformation of the matrix existing between carbon fibers is predicted based on the fiber bending information obtained through simulation, and matrix shear strain energy model is developed. Also, the relationship between the matrix shear strain energy and machining quality is analyzed. Through verification experiments under various machining conditions, it is confirmed that the quality of the machined surface deteriorated as the matrix shear strain energy increased. Moreover, this study analyzed the fiber cutting mechanism considering bent fibers during CFRP milling and proposed a method to identify the type of machining mechanism through machining sound analysis. Through experiments, it was verified that fiber bending or defects can be identified through machining sound analysis in the high-frequency range between 7,500 Hz and 14,800 Hz. From the analysis, the effect of different chip thickness in up-milling and down-milling on fiber bending was investigated by analyzing simulation and sound signal. From machining experiments, the effect of this difference on cutting force and machining quality was verified. Lastly, we developed a minimum chip thickness and fiber fracture model in CFRP milling and analyzed the effect of fractured fibers on the machining sound. Carbon fibers located below the minimum chip thickness do not contact the tool edge and are compressed by the bottom face of the tool, and these fibers are excessively bent and broken. As these broken fibers are discharged while scratching the flank face of the tool, a loud machining sound is generated. Moreover, through the verification experiment, it was confirmed that the number of broken fibers is proportional to the loudness of the sound, and calculated number of broken fibers for one second using the fiber fracture model coincides with the high-frequency machining sound range of 7,500 Hz to 14,800 Hz.</p>

<p>  </p> <p>Architectured materials offer engineers more options for choosing materials with their desired properties. Segmenting materials to create topological interlocking materials (TIMs) creates materials, which can deform in greater amounts without failure and absorb more strain energy. Previous research on TIMs has shown that the stiffness and reaction force of these materials can be directly controlled by controlling the boundary forces offered by the frame which constrains these materials.</p> <p>The research presented in this paper investigated a TIM made into a 1-Dimension beam like structure called a lintel. This research investigated not only the mechanics of this structure, but also developed a method of directly controlling the reaction force at a given displacement using shape memory alloy (SMA) wires. These wires would actuate the boundary pieces used to constrain the system. These actuation wires coupled with force sensors imbedded into the lintel allowed a feedback control loop to be established, which would control the reaction force. The reaction force was then controlled to create a smart structure which could optimize the strain energy absorption under the constraint of a maximum allowable load, similar to cellular solids used in packaging and padding materials.</p> <p>To develop this smart structure, four separate investigations occurred. The first was finite element analysis (FEA) performed to model the loading response of the lintel. This experiment demonstrated that the Mises Truss Model was effective at modelling the lintel. The second was an experimental validation of the FEA model performed in the first investigation. This experiment validated the Mises Truss Model for the lintel. The third investigation simulated the active lintel using computational software and the model of the lintel established in the first two investigations. This experiment demonstrated computationally the ability of SMA wires to control the reaction force as desired in an idealized case. The fourth and final investigation experimentally validated the ability to create and active lintel and created a functioning prototype. This demonstrated experimentally the ability of the active lintel to control reaction force as desired.</p> <p>This project has demonstrated the viability to create smart structures using segmented materials, which in the future may be used in a variety of applications including robotics and adaptive structures in harsh environments. </p>

<p dir="ltr">The dissolution profile is one of the most important critical quality attributes (CQAs) for pharmaceutical solid oral dosage forms, as failure to meet the dissolution specification can impact bioavailability. Dissolution tests are essential to assess lot-to-lot product quality and guide the development of new formulations. Therefore, predictive dissolution reduced-order models (ROM) are crucial for the successful implementation of any real-time release testing (RTRT) strategy. Mechanistic and semi-mechanistic ROMs of tablet dissolution for realizing quality by control (QbC) and RTRT frameworks in continuous manufacturing are still scarce or nonexistent. Moreover, realizing the underlying coupled mechanics of wetting, swelling, disintegration, and dissolution is still an open question. This dissertation contributes to developing a mechanistic ROM of pharmaceutical tablet dissolution for the design, optimization, and control of manufacturing processes. We follow several steps towards the progression of the mechanistic model development. First, we develop a semi-mechanistic ROM to capture the relationship between critical process parameters (CPPs), critical material attributes (CMAs), and dissolution profiles. We demonstrate the versatility and the capability of the semi-mechanistic ROM to estimate changes in dissolution due to process disturbances in tablet porosity, lubrication conditions, and moisture content in the powder blend. Next, to understand the underlying coupled mechanism of wetting, swelling, disintegration, and dissolution, we use dynamic micro-computed tomography (micro-CT) with a high temporal resolution to visualize water penetration through the porous network of immediate-release tablets. We couple liquid penetration due to capillary pressure described by the Lucas-Washburn theory with the first-order swelling kinetics of the excipients to provide a physical interpretation of the experimental observations. From the mechanistic understanding of the water penetration kinetics using the micro-CT tests, we propose a two-stage mechanistic ROM, which is comprised of (i) a mechanistic dissolution model of the active pharmaceutical ingredient (API) that solves a population balance model (PBM) for a given API crystal size distribution and dissolution rate coefficient, and (ii) a tablet wetting function that estimates the rate at which the API is exposed to the buffer solution. These two sub-models are coupled by means of convolution in time to capture the start time of the API dissolution process as water uptake, swelling, and disintegration take place. Finally, we demonstrate the versatility and the capability of the mechanistic API dissolution model and the two-stage tablet dissolution ROM to represent the dissolution profile of different pharmaceutical formulations and its connection with CMAs, CPPs, and other CQAs, namely initial API crystal size distribution, porosity, composition, and dimensions of the tablet. In all of the cases considered in this work, the estimations of the model are in good agreement with experimental data. </p>

The need to protect marine structures from the high-intensity impulsive loads created by underwater explosions has stimulated renewed interest in the mechanical response of sandwich structures. The objective of this combined numerical and experimental study is to analyze the dynamic response of composite sandwich structures and develop material-structure-property relations and design criteria for improving the blast-resistance of marine structures. Configurations analyzed include polymer foam core structures with planar geometries. A novel experimental facility to generate high-intensity underwater impulsive loads and carry out in-situ measurements of dynamic deformations in marine structures is developed. Experiments are supported by fully dynamic finite-element simulations which account for the effects of fluid-structure interaction, and the constitutive and damage response of E-glass/polyester composites and PVC foams. Results indicate that the core-density has a significant influence on dynamic deformations and failure modes. Polymeric foams experience considerable rate-effects and exhibit extensive shear cracking and collapse under high-magnitude multi-axial underwater impulsive loads. In structures with identical masses, low-density foam cores consistently outperform high-density foam cores, undergoing lesser deflections and transmitting smaller impulses. Calculations reveal a significant difference between the response of air-backed and water-backed structures. Water-backed structures undergo much greater damage and consequently need to absorb a much larger amount of energy than air-backed structures. The impulses transmitted through water-backed structures have significant implications for structural design. The thickness of the facesheets is varied under the conditions of constant material properties and core dimensions. The results reveal an optimal thickness of the facesheets which maximizes energy absorption in the core and minimizes the overall deflection of the structure.

The principal aims of this research have been the development of photogrammetric techniques for the measurement of anisotropic deformation in uniaxially loaded cylindrical specimens. This has been achieved through the use of calibrated cameras and the application of edge detection and multiple view geometry. The techniques have been demonstrated at quasi-static strain rates, 10^-3 s^-1, using a screw-driven loading device and high strain rates, 10^3 s^-1, using Split Hopkinson Bars. The materials that have been measured using the technique are nearlyisotropic steel, anisotropic cross-rolled Ti-6Al-4V and anisotropic clock-rolled commercially pure Zr. These techniques allow the surface shapes of specimens that deform elliptically to be completely tracked and measured in situ during loading. This has allowed the measurement of properties that could not have been recorded before, including true direct stress and the ratio of transverse strains in principal material directions, at quasi-static and elevated strain rates, in tension and compression. The techniques have been validated by measuring elliptical prisms of various aspect ratios and independently measuring interrupted specimens using a coordinate measurement machine. A secondary aim of this research has been to improve the characterisation of the anisotropic mechanical properties of cross-rolled Ti-6Al-4V using the techniques developed. In particular, the uniaxial yield stresses, hardening properties and the associated anisotropic deformation behaviour along the principal material directions, have all been recorded in detail not seen before. Significant findings include: higher yield stresses in-plane than in the through-thickness direction in both tension and compression, and the near transverse-isotropy of the through-thickness direction for loading conditions other than quasi-static tension, where significant anisotropy was observed.