Nowadays, timber is widely used in construction industry thanks to its availability and good properties. The use of solid (sawn) timber is not always proper since it is only available up to certain dimensions. Therefore, the so-called Engineered WoodProducts (EWPs) have been introduced to cope with the different design needs of structures. The Glued laminated Timber (glulam) is a type of EWPs that consists of smallsections of timber laminates glued together to form beams and columns. Glulam can be manufactured in almost any size and shape; it can also be tapered or notched. However, notching a beam at its end leads to a stress concentration at the re-entrantcorner of the notch due to the sudden change in the notched beam’s cross section. The concentration of shear and tensile stresses perpendicular to the grain can lead to a catastrophic brittle failure caused by the crack propagation from the notch corner. Crack opening due to tensile stresses perpendicular to grain is the most common failure at the notch corner and it is always taken into design consideration. However,shear component is usually exists and must be also considered in design to guarantee the safety of the structure. Currently, only the normal forces perpendicular to the beam’s axis are considered in the design of the reinforcement in design handbooks. The aim of this thesis was to study the structural behavior of notched glulam beams reinforced by adhered plywood panels and FRP. The carrying capacity of the notched glulam beams at their ends is the main subject of this thesis. In addition, a review of the notched beams design, reinforcements, and analysis theories are included. Experimental series of three point bending tests with notched glulam beams withdifferent configurations of reinforcement was carried out in lab. Deformations and forces were measured both with conventional techniques and with contact-free measurement systems - ARAMIS. On the other hand, a simple model of two dimensional plane stress element has been created of the unreinforced notchedbeam in ABAQUS. The normal and shear stresses were calculated for a horizontalpath of 100 mm in length starting from the notch tip. Afterwards, the mean stresseswere determined for the same path and have been used in calculations. The Mean Stress Approach has been adopted in the hand calculations to calculate the crack length and the failure load according to the ABAQUS model. Accordingly, the failure load was about 40 kN for the unreinforced beams. Also, Eurocode 5 has been used to calculate the failure load which gave a value of 20.2 kN for the unreinforced beams. The average maximum applied load in tests was 30 kN for the unreinforced beams while it reached about two and a half times this value for the CF-reinforced and the plywood-reinforced beams. / Tack vare sina goda egenskaper används trä i byggnadskonstruktioner i allt storeomfattning. Konstruktionsvirke (sågade trävaror) kan dock inte alltid användas pågrund av de begränsade dimensioner som finns tillgängliga. På grund av bl a dettahar ett flertal så kallade engineer wood products (EWP) utvecklats. Limträ är en typav EWP som består av sammanlimmade lameller som bygger upp tvärsnitt i balkareller pelare. Limträ kan tillverkas i nästan godtycklig storlek och form och kan enkeltförses med t ex urtag. Vid urtag i balkändar nära upplag uppstår högaspänningskoncentrationer vid urtagets horn på grund av geometrin. Koncentrationenav normalspänningar och skjuvspänningar kan leda till plötsligt brott på grund avsprickpropagering från urtagets hörn, något som måste tas hänsyn till viddimensionering. Dagens dimensioneringsmetoder är baserade på att man tar hänsyntill enbart normalspänningarna vinkelrät fiberriktningen.Målet med detta arbete har varit att studera beteendet hos limträbalkar med urtag vidupplag som förstärkts med fiberarmering eller plywood. Huvudmålet har varit attbestämma balkarnas bärförmåga, vilket skett genom att genomföra försök med olikakonfigurationer vad gäller förstärkningsmaterial och dess utformning. Vidare harolika dimensioneringsmetoder från litteraturen studerats.Kraft och förskjutning under provningarna uppmättes dels med traditionellamätmetoder, men deformationerna mättes även med beröringsfri metod, ARAMIS.En enkel tvådimensionell finit elementmodell skapades och analyserades i ABAQUSför analys av oförstärkt balk. Normalspänningar och skjuvspänningar beräknades ochmedelspänningarna längs en på förhand definierad sträcka beräknades.Medelspänningskriteriet användes sedan för att uppskatta balkens bärförmåga.Enligt FE-beräkningarna uppskattades bärförmågan för de oförstärkta balkarna till ca40 kN. Provningarna gav ett medelvärde på balkarnas bärförmåga på ca 30 kN,medan de förstärkta balkarna hade en 2,5 gånger högre bärförmåga. Skillnadenmellan FE-beräkningarna och provningarna kan förklaras med den osäkerhet somfinns vad gäller det aktuella trämaterialets egenskaper.Beräkningar enligt Eurokod 5 gav en karakteristisk bärförmåga på 20,2 kN.

When doing finite element analysis upon the structure of Saab’s aeroplanes a coarse global model of mainly shell elements is used to determine the load distribution for sizing the structure. At some parts of the aeroplane it is however desirable to implement a more detailed analysis. These areas are usually modelled with solid elements; the problem of connecting the fine local solid elements to the coarse global model will shell elements then arises.   This master thesis is preformed to investigate possible Global-Local methods to use for the structural analysis on Gripen. First a literature study of current methods on the market is made, thereafter a few methods are implemented on a generic test structure and later on also tested on a real detail of Gripen VU. The methods tested in this thesis are Mesh refinement in HyperWorks, RBE3 in HyperWorks, Glue in MSC Patran/Nastran and DMIG in MSC Nastran. The software is however not evaluated in this thesis, and a further investigation is recommended to find the most fitting software for this purpose. All analysis are performed with linear assumptions.   Mesh refinement is an integrated technique where the elements are gradually decreasing in size. Per definition, this technique cannot handle gaps, but it has almost identical results to the fine reference model.   RBE3 is a type of rigid body elements with zero stiffness, and is used as an interface element. RBE3 is possible to use to connect both Shell-To-Shell and Shell-To-Solid, and can handle offsets and gaps in the boundary between the global and local model.   Glue is a contact definition and is also available in other software under other names. The global respectively the local model is defined as contact bodies and a contact table is used to control the coupling. Glue works for both Shell-To-Shell and Shell-To-Solid couplings, but has problem dealing with offsets and gaps in the boundary between the global and local model.   DMIG is a superelement technique where the global model is divided into smaller sub-models which are mathematically connected. DMIG is only possible to use when the nodes on the boundary on the local model have the same position as the nodes at the boundary of the global model. Thus, it is not possible to only use DMIG as a Global-Local method, but can advantageously be combined with other methods.   The results indicate that the preferable method to use for Global-Local analysis is RBE3. To decrease the size of the files and demand of computational power, RBE3 can be combined with a superelement technique, for example DMIG.   Finally, it is important to consider the size of the local model. There will inevitably be boundary effect when performing a Global-Local analysis of the suggested type, and it is therefore important to make the local model big enough so that the boundary effects have faded before reaching the area of interest.

Asphalt pavement rutting is one of the most commonly observed pavement distresses and is a major safety concern to transportation agencies. Millions of dollars are reportedly spent annually to repair rutted asphalt pavements. Research into improvements of hot-mix asphalt materials, mix designs and methods of pavement evaluation and design, including laboratory and field testing, can provide extended pavement life and significant cost savings in pavement maintenance and rehabilitation. This research describes a method of predicting the behaviour of various asphalt mixes and linking these behaviours to an accelerated performance testing tool and pavement in-situ performance. The elastic, plastic, viscoelastic and viscoplastic components of asphalt mix deformation are also examined for their relevance to asphalt rutting prediction. The finite element method (FEM) allows for analysis of nonlinear viscoplastic behaviour of asphalt mixes. This research determines the critical characteristics of asphalt mixes which control rutting potential and investigates the methods of laboratory testing which can be used to determine these characteristics. The Hamburg Wheel Rut Tester (HWRT) is used in this research for asphalt laboratory accelerated rutting resistance testing and for calibration of material parameters developed in triaxial repeated load creep and creep recovery testing. The rutting resistance criteria used in the HWRT are developed for various traffic loading levels. The results and mix ranking associated with the laboratory testing are compared with the results and mix ranking associated with FEM modeling and new mechanistic-empirical method of pavement design analyses. A good relationship is observed between laboratory measured and analytically predicted performance of asphalt mixes. The result of this research is a practical framework for developing material parameters in laboratory testing which can be used in FEM modeling of accelerated performance testing and pavement in-situ performance.

Motor vehicle accidents continue to be a leading cause of cervical spine injury despite a conscientious effort to improve occupant safety. Accurately predicting occupant head and neck response in numerical crash simulations is an essential part of the process for developing better safety solutions. <br /><br /> A biofidelic model of the human cervical spine was developed with a focus on accurate representation of the cervical spine at the local tissue level. These tissues were assembled to create a single segment model that was representative of <em>in vitro</em> spine in quasi-static loading. Finally, the single segment models were assembled to create a full cervical spine model that was simulated in dynamic loading and compared to human volunteer response. <br /><br /> Models of each segment were constructed from the basic building blocks of the cervical spine: the intervertebral disc, the vertebrae, the ligaments, and the facet joints. Each model was simulated in all modes of loading and at different levels of load. The results of the study indicate that the cervical spine segments performed very well in flexion, compression, and tension. Segment response to lateral bending and axial rotation was also good, while response in extension often proved too compliant compared to the experimental data. Furthermore, the single segment models did not fully agree with the experimental shear response, again being more compliant. <br /><br/> The full cervical spine model was assembled from the single segment models incorporating neck musculature. The model was simulated dynamically using a 15 G frontal impact test. Active muscles were used to simulate the response of the human volunteers used in the study. The response of the model was in reasonable agreement with the experimental data, and compared better than current finite element cervical spine models. Higher frequency oscillation caused most of the disagreement between the model and the experimental data, which was attributed to a lack of appropriate dynamic material properties of the soft tissues of the spine. In addition, a study into the active properties of muscle indicated that muscle response has a significant influence on the response of the head. <br /><br /> A number of recommendations were proposed that would improve the biofidelity of the model. Furthermore, it was recommended that the future goal of this model would be to implement injury-predicting capabilities through the development of advance material models.

Two efficiency-based grid refinement strategies are investigated for adaptive finite element solution of partial differential equations. In each refinement step, the elements are ordered in terms of decreasing local error, and the optimal fraction of elements to be refined is deter- mined based on e±ciency measures that take both error reduction and work into account. The goal is to reach a pre-specified bound on the global error with a minimal amount of work. Two efficiency measures are discussed, 'work times error' and 'accuracy per computational cost'. The resulting refinement strategies are first compared for a one-dimensional model problem that may have a singularity. Modified versions of the efficiency strategies are proposed for the singular case, and the resulting adaptive methods are compared with a threshold-based refinement strategy. Next, the efficiency strategies are applied to the case of hp-refinement for the one-dimensional model problem. The use of the efficiency-based refinement strategies is then explored for problems with spatial dimension greater than one. The work times error strategy is inefficient when the spatial dimension, d, is larger than the finite element order, p, but the accuracy per computational cost strategy provides an efficient refinement mechanism for any combination of d and p.

Cervical spine injury can range from minor to severe or fatal, where severe injuries can result in incomplete or complete quadriplegia. There are close to 45,000 Canadians currently affected by paralysis due to traumatic spinal cord injury (tSCI) with an estimated 1700 new cases each year. The majority of tSCI occur in automotive collisions, and current methods for injury prediction are limited to predicting the likelihood for occupant injury but lack the detail to predict the specific injury and location at the tissue level. This research focused on major injuries associated with high impact automotive collisions such as rollover type collisions. Although whiplash is an injury commonly associated with automotive collisions, it was not considered for this study based on the low risk of neurological impairment. The goal of this study was to develop a cervical spine segment finite element model capable of predicting severe injuries such as ligament tears, disc failure, and bone fracture. The segment models used in this study were developed from previous cervical spine segment models representative of a 50th percentile male. The segment models included the vertebrae, detailed representations of the disc annulus fibres and nucleus, and the associated ligaments. The original model was previously verified and validated under quasi-static loading conditions for physiological ranges of motion. To accomplish the objectives of this research, the original models were modified to include updated material properties with the ability to represent tissue damage corresponding to injuries. Additional verification of the model was required to verify that the new material properties provided a physically correct response. Progressive failure was introduced in the ligament elements to produce a more biofidelic failure response and a tied contact between the vertebral bony endplates and the disc was used to represent disc avulsion. To represent the onset of bone fracture, a critical plastic strain failure criterion was implemented, and elements exceeding this criterion were eroded. The changes made to the material models were based on experimental studies and were not calibrated to produce a specific result. After verifying the modifications were implemented successfully, the models were validated against experimental segment failure tests. Modes of loading investigated included tension, compression, flexion, extension and axial rotation. In each case, the simulated response of the segment was evaluated against the average failure load, displacement at failure, and the observed injuries reported in the experimental studies. Additionally, qualitative analysis of elevated stress locations in the model were compared to reported fracture sites. Overall, the simulations showed good agreement with the experimental failure values, and produced tissue failure that was representative of the observed tissue damage in the experimental tests. The results of this research have provided a solid basis for cervical spine segment level injury prediction. Some limitations include the current implementation of bone fracture under compressive loads, and failure within the annulus fibrosus fibres of the disc should be investigated for future models. In addition to material model modifications, further investigation into the kinetics and kinematics of the upper cervical spine segment are important to better understand the complex interactions between the bone geometry and ligaments. This would give insight into the initial positioning and expected response in subsequent models. Future research will include integrating the current segment-level failure criteria into a full cervical spine model for the purpose of predicting severe cervical spine injury in simulated crash scenarios, with future applications in sports injury prevention and protective equipment.

Micro-motion devices may share a common architecture such that they have a main body of compliant material and some direct actuation elements (e.g., piezoelectric element). The shape of such a compliant material is designed with notches and holes on it, and in this way one portion of the material deforms significantly with respect to other portions of the material a motion in the conventional sense of the rigid body mechanism. The devices of this kind are called compliant mechanisms. Computer tools for the kinematical and dynamic motion analysis of the compliant mechanism are not well-developed. In this thesis a study is presented towards a finite element approach to the motion analysis of compliant mechanisms. This approach makes it possible to compute the kinematical motion of the compliant mechanism within which the piezoelectric actuation element is embedded, as opposed to those existing approaches where the piezoelectric actuation element is either ignored or overly simplified. Further, the developed approach allows computing the global stiffness and the natural frequency of the compliant mechanism. This thesis also presents a prototype compliant mechanism and a test bed for measuring various behaviors of the prototype mechanism. It is shown that the developed approach can improve the prediction of motions of the compliant mechanism with respect to the existing approaches based on a comparison of the measured result (on the prototype) and the simulated result. The approach to computation of the global stiffness and the natural frequency of the compliant mechanism is validated by comparing it with other known approaches for some simple mechanisms.

The mechanism of soil-reinforcement interaction for a reinforced embankment on soft clay has been explored by conducting a parametric study using a coupled non-linear elastoplastic finite element program. One of the major issues in the design of a reinforced embankment on soft clay is the magnitude of tension that can be mobilized in the geosynthetic reinforcement. Previous research using geotechnical centrifuge modelling and present research using finite element modelling has confirmed that the tension mobilized in the reinforcement is only of the order of active lateral thrust in the embankment. The parametric study has revealed that the soil-reinforcement interaction mechanism depends on the ratio of embankment height to the depth of the clay layer. The embankment behaves similar to a rigid footing in case of deep clay deposit. In this case, the failure mechanism is similar to a slip circle and there is very little contribution from the clay-reinforcement interface towards the mobilization of reinforcement tension. However, if the depth of clay deposit is small, the soil-reinforcement interaction mode is similar to direct shear failure and slip surface is located close to the clay-reinforcement interface. In this case, the contribution of clay-reinforcement interface towards the tension mobilized in the reinforcement is higher and therefore, the contribution of the reinforcement towards overall stability of the embankment is greater. Based on the results of the parametric study a novel serviceability criterion is proposed that aims to limit the lateral deformation of the clay foundation at the toe of the embankment by limiting the allowable mobilized tension in the reinforcement. A simple procedure for the evaluation of the efficiency of soil-reinforcement interface for reinforced embankments on soft clays is also proposed. The validity of the proposed serviceability criterion and the design charts was successfully tested using two field case studies. Sackville test embankment constructed to failure in 1989 and a levee test section that remained serviceable after construction in 1987 at Plaquemine, Louisiana were able to confirm the validity of the serviceability criterion proposed in the present study.

<p>Methodologies for the analysis and computer simulations of active optimal vibration control of complex elastic structures are considered. The structures, generally represented by a large number of degrees of freedom (DOF), are to be controlled by a comparatively small number of actuators.</p><p>Various techniques presently available to solve the optimal control problems are briefly discussed. A Parametric optimization technique that is versatile enough to solve almost any type of optimization problems is found to give poor accuracy and is time consuming. More promising is the optimality equations approach, which is based on Pontryagins principle. Several new numerical procedures are developed using this approach. Most of the problems in this thesis are analysed in the modal space. Even complex structures can be approximated accurately in the modal space by using only few modes. Different techniques have been first applied to the cases where the number of modes to control was the same as the number of actuators (determined optimal control problems), then to cases in which the number of modes to control is larger than the number of actuators (overdetermined optimal control problems). </p><p>The determined optimal control problems can be solved by applying the Independent Modal Space Control (IMSC) approach. Such an approach is implemented in the Beam Analogy (BA) method that solves the problem numerically by applying the Finite Element Method (FEM). The BA, which uses the ANSYS program, is numerically very efficient. The effects of particular optimization parameters involved in BA are discussed in detail. Unsuccessful attempts have been made to modify this method in order to make it applicable for solving overdetermined or underactuated problems. </p><p>Instead, a new methodology is proposed that uses modified optimality equations. The modifications are due to the extra constraints present in the overdetermined problems. These constraints are handled by time dependent Lagrange multipliers. The modified optimality equations are solved by using symbolic differential operators. The corresponding procedure uses the MAPLE programming, which solves overdetermined problems effectively despite of the high order of differential equations involved.</p><p>The new methodology is also applied to the closed loop control problems, in which constant optimal gains are determined without using Riccatis equations.</p>

This work develops a methodology for full engine FEA simulation of the fan blade off containment test for a jet engine using LS-Dyna. The fan blade off containment test is a safety requirement involving the intentional release of a fan blade when the engine is running at full power. The released blade must not pierce or fracture the engine cases during the impact or rotating unbalance. The novel feature of the LS-Dyna simulation is the extensive full engine geometry as well as the widespread use of nonlinearities (mainly plasticity and friction) to absorb the large kinetic energies of the engine rotors. The methodology is simple to use, runs quickly and is being recognized by industry as a contender for widespread implementation. Future applications look promising enough that the methodology warrants further development and refinement.