This thesis contributes towards understanding of mechanical response of 3D composites and ceramics. Composite materials have widespread applications ranging from aerospace, civil sectors to sports and drones. One important application is in composite armours where composites and ceramic layers are used together. Therefore, it is important to study the mechanical response of these components to develop better armour systems. The first part of this thesis concerns with dynamic penetration response of confined ceramic targets. In the second part, mechanics of a novel 3D composite consisting of orthogonal carbon fibre tows is studied. The dynamic penetration of ceramic target by a long-rod projectile is studied using a mechanism based ceramic constitutive model. This is to capture and explain the essential physics observed during penetration of a ceramic target such as dwell and structural size effect. Dwell is captured using the constitutive model and the related physics is studied along with identification of causes of dwell. Origins of structural size effect in ceramics are identified and their influences are studied. In the second part of the thesis a novel 3D composite consisting of three mutually perpendicular orthogonal tows is studied under compression, indentation and three-point bending. Under compression along low fibre volume fraction direction (Z), the 3D composite forms stable and multiple kinks in the Z tows resulting in 10% ductility. This contrasts with traditional UD or 2D composites which fail catastrophically at 2% strain. The stability in the case of the 3D composite is due to the constraint imposed by the surrounding material. Under indentation, the 3D composite has a near isotropic and ductile response. In contrast, traditional cross-ply composites show highly anisotropic response where indentation results in brittle failure along in-plane direction. Under three-point bending, the response was ductile in Z-direction and brittle in other two directions. Overall, the 3D composite studied in this thesis shows improvement over traditional CFRPs in ductility and energy absorption capability. The 3D composite has been demonstrated to have smooth load-displacement curves reminiscent to indentation of metal in all three directions achieved at densities significantly lower than structural metals that display equivalent ductility. Thus, these 3D composites are strong candidates for applications where loading direction is unknown a-priori, and where high energy absorption is required along with reusability of the material.

This study investigates the global stiffness of a timer frame structure under wind loading using the finite element method by creating parameterized script files. Of key interest was the accuracy of the global stiffness determined from an adaptive 3D beam model in comparison to a 2D beam model and, the stiffness of a 3D beam model when subjected to different types of bracing in the presence of internal bracing provided by a lift shaft structure. Investigation of contact forces on the surfaces between the fastener and the timber at the connection was carried out and a design check for the specified bolts shear capacity done with respect to Eurocode 5. A 3D adaptive connection was created for a 2D frame model and the stiffness of the structure was studied. A comparison of the maximum displacement of the structure in the x direction, under the same wind loading, spring stiffness and boundary conditions, with a 2D beam structure without the adaptive connection initially showed a difference in the displacement. This implied that the rotational stiffness in the beam model was greater than that of the adaptive connection created. Therefore after altering the rotational stiffness of the beam model to achieve similar displacement as in the adaptive model, the rotational stiffness of the created connection was found to be 33.4 · 106Nm. The study also determined the contact forces generated at the surfaces between the fasteners and the timber using the finite element method to integrate over the surfaces and calculate the forces. The results were generated using the History Output in the step module. The only disadvantage of acquiring the contact forces was that, the contact surface simulation caused larger run times for the model to complete the time step. For the adaptive model it took 18 hours to complete each step. Further investigation into the stiffness of a 3D frame structure was conducted. The model of the 3D structure was created by a parameterized script which makes it easy to change input variables such as number of internal walls, geometry in x-z-plane, number of storeys, cross-sectional dimensions, material properties number of diagonals and location of diagonals. A variety of models with different conditions was analyzed. This showed that stiffness has a major impact on the magnitude of reaction forces and displacements.

Today, high performance steel as a construction material is treated as conventional steel in the European standards. Referring to the Eurocodes, the buckling curves for dimensioning of steel constructions only presents values up to steel grade S460, meaning that the full potential of high performance steel is not considered. If the amplitude of the residual stresses in high performance steel can be confirmed to be smaller than in conventional steel, more slender cross sections could be obtained when using high performance steel, HPS. One challenge with the residual stress patterns for HPS is its variation obtained in different studies, where new resulting residual stress patterns are found depending on plate thickness and manufacturing methods for the steel.   Residual stresses in steel are stresses not associated with external forces. The stresses are instead caused by internal forces, such as differencing temperature. Residual stresses can therefore be connected to stresses due to welding. Considering HPS, it is distinctive from conventional steel in the way that it has higher performance in tensile strength, toughness, weldability, corrosion and cold formability.   This study has been performed by Finite Element Modelling in the software Abaqus and by performing an experiment. The objective of this study was to find residual stress patterns and to compare the results with existing residual stress patterns according to the European Convention for Constructional Steel (ECCS) and the Swedish handbook for steel constructions provided by Boverket (BSK 07), but also to compare the results with previous studies.   The influence of temperature changes due to welding was studied for a L-section made of steel S690QL, where only the longitudinal stresses were considered during the research. The numerical analysis in Abaqus was performed using a DFlux subroutine, which is written in Fortran language. Furthermore, the analysis was divided into subparts; one heat transfer analysis and two three-dimensional stress analyses for two different boundary conditions, with the purpose of obtaining results in terms of temperature and stresses for further analysis. The experimental work was performed on three specimens using Gas Metal Arc Welding, where thermocouples and strain gages were used for measuring temperature and strains respectively.   Conclusions of this study were that the resulting residual stress pattern obtained the experiment was similar to the stress pattern for a L-section in BSK 07, while the resulting residual stress pattern obtained in the numerical analysis was mostly comparable to ECCS, but with similarities to BSK 07 and a previous study by Cherenenko & Kennedy (1990).  Moreover, the resulting residual tensile stresses obtained in the study had the same amplitude or lower than what is specified in BSK 07.

Intumescent coating fire protection on steel structures is becoming widely popular in the UK and Europe. The current assessment for the fire protection performance method using the standard fire resistance tests is not accurate, owing to the reactive behaviour of intumescent coating at elevated temperature. Moreover, the available intumescent coating temperature assessment method provided in the Eurocode for structural steel at elevated temperature does not incorporate the steel beam's behaviour and/or assessment for partial protection and/or damaged protection. The research work presented provides additional information. on the assessment of partial and/or damaged intumescent coating at elevated temperature. In the scope of the investigation on the thermal conductivity of intumescent coating, it was found that the computed average thermal conductivity was marginally sensitive to the density and emissivity at elevated temperature. However, the thermal conductivity was found to be reasonably sensitive to the differences in initial dft's (dry film thicknesses). In this research, a numerical model was developed using ABAQUS to mimic actual indicative test scenarios to predict and establish the temperature distribution and the structural fire resistance of partial and/or damaged intumescent coating at elevated temperatures. Intumescent coating actively shields when the charring process occurs when the surface temperature reaches approximately 250°C to 350°C. Maximum deflection and deflection failure times for each damage scenario were analyzed by applying specified loading conditions. It was also found that the structural fire resistance failure mode of intumescent coating on protected steel beams was particularly sensitive to the applied boundary conditions. Careful selection of nodes in the element was necessary to avoid numerical instability and unexpected numerical error during analysis. An assessment of various numerical models subjected to a-standard fire with partially protected 1 mm intumescent coating was analysed using ABAQUS. An available unprotected test result was used as a benchmark. The outcome suggests that the fire resistances of the beams were found to be sensitive to the location of the partial and/or damage protection. The overall fire resistance behaviour of intumescent coating at elevated temperature was summarized in a 'typical deflection regression' curve. An extensive parametric analysis was performed on localized intumescent coating damage with various intumescent coating thicknesses between 0.5mm to 2.0mm. It was found that the average deflection was linear for the first 30 mins of exposure for all the variables, damage locations and intumescent thicknesses. It was concluded that a thicker layered intumescent coating may not be a better insulator or be compared to a much less thick intumescent coating at elevated temperature. The use of passive fire protection, however, does enhance the overall fire resistance of the steel beam, in contrast to a naked steel structure. The research work investigated the intumescent coating behaviour with different aspects of protection and damage and the outcome of the assessment provided a robust guide and additional understanding of the performance of intumescent coating at elevated temperature.

Brush seals are contact seals which are efficient and reliable and can beused in any rotatory machinery. A theoretical model of a brush seal wassuggested and used for a simulation study. Comparison between the resultsof the experiment and simulation is used to verify the accuracy of model.Following the basic simulation steps, more simulation will be done to geta further analysis. The further analysis will be studied in bristles’ bucklingcharacteristics, deformation and stress. The buckling, stress anddeformation is related to the brush seal’s performance. This work givesthe different geometry of bristle’s effect to its buckling characteristics andthe study of stress and deformation caused by fluid flow across bristlesduring operation.

No description available.

Wind-induced damages on low-slope roofs are a major and common problem that many buildings located in high wind areas suffer from. Most of these damages are initiated when the metal roof edge fails first, leading to overall roof failure. This is because peak wind pressures occur at the edges and corners of low-slope roof buildings. Currently, there are not enough wind design guidelines for the Canadian roofing community to quantify the dynamic wind uplift resistance of the roof edge system. The objective of this research is to evaluate the effect of wind-induced loads on roof edges using a finite element model, verify the numerical results with those obtained from controlled experiments, and perform parametric investigations for various design variables. In this research, the overall roof edge system was modelled using the commercial finite element software package ABAQUS, by simulating the roof edge system with shell elements and applying a uniform static pressure against the face of the edge cleat or coping. Results of the modelling were compared to the experimental ones in terms of deflection of the coping under uniform pressure. The results of the numerical model and the experiments show a good agreement. Furthermore, a parametric analysis of the system was conducted under the effect of varying parameters. i.e., coping gauge, nail spacing, coping and cleat length and wind and thermal load application.

A finite element model of fibre metal laminate (FML) fuselage was developed in order to evaluate its impact response under survivable crash event. To create a reliable crash finite element (FE) model of FML fuselage, a ‘building block approach’ is adapted. It involves a series of validation and verification tasks in order to establish reliable material and damage models, verified impact model with structural instability and large displacement and verified individual fuselage structure under crash event. This novel development methodology successfully produced an FE model to simulate crash of both aluminium alloy and FML fuselage under survivable crash event using ABAQUS/Explicit. On the other hand, this allows the author to have privilege to evaluate crashworthiness of fuselage that implements FML fuselage skin for the whole fuselage section for the first time in aircraft research field and industry. The FE models consist of a two station fuselage section with one meter longitudinal length which is based on commercial Boeing 737 aircraft. For FML fuselage, the classical aluminium alloy skin was replaced by GLARE grade 5-2/1. The impact response of both fuselages was compared to each other and the results were discussed in terms of energy dissipation, crushing distance, failure modes, failure mechanisms and acceleration response at floor-level. Overall, it was observed that FML fuselage responded similarly to aluminium alloy fuselage with some minor differences which conclusively gives great confidence to aircraft designer to use FML as fuselage skin for the whole fuselage section. In terms of crushing distance, FML fuselage skin contributed to the failure mechanisms of the fuselage section that lead to higher crushing distance than in aluminium alloy fuselage. The existence of various failure modes within FML caused slight differences from the aluminium fuselage in terms of deformation process and energy dissipation. These complex failure modes could potentially be manipulated to produce future aircraft structure with better crashworthiness performance.

A finite element modeling strategy targeting package opening simulations is the final goal with this work. The developed simulation model will be used to proactively predict the opening compatibility early in the development process of a new opening device and/or a new packaging material. To be able to create such a model, the focus is to develop a combined and integrated physical/virtual test procedure for mechanical characterization and calibration of thin packaging materials. Furthermore, the governing mechanical properties of the materials involved in the opening performance needs to be identified and quantified with experiments. Different experimental techniques complemented with video recording equipment were refined and utilized during the course of work. An automatic or semi-automatic material model parameter identification process involving video capturing of the deformation process and inverse modeling is proposed for the different packaging material layers. Both an accurate continuum model and a damage material model, used in the simulation model, were translated and extracted from the experimental test results. The results presented show that it is possible to select constitutive material models in conjunction with continuum material damage models, adequately predicting the mechanical behavior of intended failure in thin laminated packaging materials. A thorough material mechanics understanding of individual material layers evolution of microstructure and the micro mechanisms involved in the deformation process is essential for appropriate selection of numerical material models. Finally, with a slight modification of already available techniques and functionalities in the commercial finite element software AbaqusTM it was possible to build the suitable simulation model. To build a realistic simulation model an accurate description of the geometrical features is important. Therefore, advancements within the experimental visualization techniques utilizing a combination of video recording, photoelasticity and Scanning Electron Microscopy (SEM) of the micro structure have enabled extraction of geometries and additional information from ordinary standard experimental tests. Finally, a comparison of the experimental opening and the virtual opening, showed a good correlation with the developed finite element modeling technique. The advantage with the developed modeling approach is that it is possible to modify the material composition of the laminate. Individual material layers can be altered and the mechanical properties, thickness or geometrical shape can be changed. Furthermore, the model is flexible and a new opening device i.e. geometry and load case can easily be adopted in the simulation model. Therefore, this type of simulation model is a useful tool and can be used for decision support early in the concept selection of development projects.

Abstract The cold spray process is an additive manufacturing technology primarily suited for ductile metals, and mainly utilized in coating surfaces, manufacturing of freeform parts and repair of damaged components. The process involves acceleration of solid micro-particles in a supersonic gas flow and coating build-up by bonding upon high velocity impact onto a substrate. Coating deposition relies on the kinetic energy of the particles. The main objective of this study was to investigate the mechanics of polymer cold spray process and deformation behavior of polymers to improve technological implementation of the process. A finite element model was created to simulate metal particle impact for copper and aluminum. These results were compared to the numerical and experimental results found in the literature to validate the model. This model was then extended to cover a wide range of impact conditions, in order to reveal the governing mechanisms of particle impact and rebound during cold spray. A systematic analysis of a single high-density polyethylene particle impacting on a semi-infinite high density polyethylene substrate was carried out for initial velocities ranging between 150m/s and 250m/s by using the finite element analysis software ABAQUS. A series of numerical simulations were performed to study the effect of a number of key parameters on the particle impact dynamics. These key parameters include: particle impact velocity, particle temperature, particle diameter, and particle density, composition of the polyethylene particle, surface composition and the thickness of a polyethylene film on a hard metal substrate. The effect of these parameter variations were quantified by tracking the particle temperature, deformation, plastic strain and rebound kinetic energy. The variation of these parameters helped define a window of deposition where the particle is mostly likely to adhere to the substrate.