abstract: This research summarizes the validation testing completed for the material model MAT213, currently implemented in the LS-DYNA finite element program. Testing was carried out using a carbon fiber composite material, T800-F3900. Stacked-ply tension and compression tests were performed for open-hole and full coupons. Comparisons of experimental and simulation results showed a good agreement between the two for metrics including, stress-strain response and displacements. Strains and displacements in the direction of loading were better predicted by the simulations than for that of the transverse direction. Double cantilever beam and end notched flexure tests were performed experimentally and through simulations to determine the delamination properties of the material at the interlaminar layers. Experimental results gave the mode I critical energy release rate as having a range of 2.18 – 3.26 psi-in and the mode II critical energy release rate as 10.50 psi-in, both for the pre-cracked condition. Simulations were performed to calibrate other cohesive zone parameters required for modeling. Samples of tested T800/F3900 coupons were processed and examined with scanning electron microscopy to determine and understand the underlying structure of the material. Tested coupons revealed damage and failure occurring at the micro scale for the composite material. / Dissertation/Thesis / Masters Thesis Civil, Environmental and Sustainable Engineering 2018

La collision d'un camion sur un pont est un événement courant et peut engendrer des efforts considérables dans la structure. Selon la norme canadienne CSA-S6-14, la pile d'un pont doit être conçue pour résister à une charge statique de 1400 kN à 1,2 m au-dessus du niveau du sol. Peu d'études récentes abordent ce sujet et aucune des études trouvées dans la littérature ne présente des résultats expérimentaux. Le but de ce mémoire est d'approfondir davantage nos connaissances sur le phénomène des collisions d'un véhicule avec un pont et de recueillir des résultats tant expérimentaux que numériques. La méthode expérimentale comprend les essais en laboratoire de deux piles en béton armé à échelles réduites 1:6 ainsi que la modélisation de ces essais à l'aide d'un modèle par éléments finis avec le logiciel LS-DYNA. Le premier essai consiste à imposer un chargement cyclique quasi-statique au niveau du chevêtre de la pile. Ceci permet de caractériser la pile et de calibrer un modèle numérique statique. Par la suite, un deuxième modèle numérique incluant la super-structure est utilisé pour simuler la collision d'un camion semi-remorque sur la pile étudiée. Les résultats du déplacement du chevêtre en fonction du temps du modèle numérique sont par la suite utilisés comme cas de chargement du deuxième essai. Finalement, un troisième modèle numérique est calibré à l'aide des résultats expérimentaux du deuxième essai. Les résultats démontrent que le montage expérimental ainsi que le modèle numérique reproduisent avec succès une charge d'impact. De plus, la nature dynamique de l'essai atteint des taux de déformations dans l'armature au-dessus de la limite quasi-statique. L'essai dynamique présente donc une charge pseudo-statique supérieure à la charge quasi-statique équivalente. Finalement, la force pseudo-statique maximale à l'échelle 1:1 atteint plus de 1832 kN alors que la force prescrite par la norme CSA-S6-14 est de 1400 kN.

The South Nation watershed is located in Eastern Ontario, Canada and managed under the authority of the South Nation Conservation (SNC). The watershed covers an area of 400,000 hectares with four dominant categories of land-use classes (60% agriculture, 34% forest, 5% mixed urban, and 1% other). Water quality is a great concern for the SNC as many anthropogenic activities generate harmful pollutants (such as heavy metals, nitrogen, phosphorus, and pesticides) that are discharged to the river through surface and groundwater flow. The discharge patterns of these pollutants are mainly driven by land-use distribution within the watershed which has been constantly evolving with urbanization and intensification of agriculture. Major changes in land-uses can potentially offset current SNC efforts to mitigate water pollution. The objective of the current study is to predict land-use series of maps for the South Nation watershed starting from 1991 to 2020. The prediction is carried out using the land-use allocation algorithm of the Dyna-CLUE (Dynamic Conversion of Land-Use and its Effects) model which is implemented for local regions. Dyna-CLUE is a spatially explicit hybrid land-use allocation model that combines estimation and simulation models, and its allocation procedures predict future trends of land-use surface (estimated from historical trends). The binary logistic regression is used to link preferences of land-use classes and potential demographic and geographic driving factors. Expert judgment was used to select a set of spatial driving factors believed to be responsible for changes in land-use distribution in the South Nation watershed. Three different scenarios for future development of the region were considered, with different initial conditions and conversion restrictions. The simulation results were evaluated using visual and statistical validation techniques to assess the performance of the model in generating maps similar to reality. The Dyna-CLUE model was successfully applied to the South Nation watershed. It was observed that the simulated maps generated from the model were in good agreement with the reality maps. This was confirmed through statistical validation via map pair analysis (error matrix) used to assess the overall accuracy of the model predictions. Results showed that the model was sensitive to land-use restrictions. Such type of modeling can be valuable for assessing the land-use changes at the local level, and setting up a decision support system for the South Nation Conservation towards sustainable land-use management in the watershed. Better results are expected to be achieved with more reliable datasets (i.e., accurate classification of land-use types in reality maps). Data availability and quality were the main obstacles that faced this research work. Our work has the merit to be the first application of CLUE model in Eastern Ontario.

Unmanned aircraft systems (UASs) pose a potential threat to general aviation/commercial aircraft as UASs are increasingly incorporated into the National Airspace System. This overarching research is aimed at addressing the severity of a UAS mid-air collision with another aircraft. This study is primarily focused on the development of a finite element (FE) model of a ~4 lb fixed-wing UAS (FW-UAS) which will be used to evaluate the severity of small UAS mid-air collisions to manned aircraft. A series of impact tests were performed at the University of Dayton Research Institute - Impact Physics Lab, to study the impact behavior of the high-density components of the FW-UAS (i.e., motor, and battery). For each of the tests, a simulation was set up with the same initial conditions, and boundary conditions as the physical test and the same output parameters were correlated with the test results. A series of numerical stability checks were also performed using the validated FW-UAS FE model to ensure the stability of the explicit dynamic procedures. Simulated impacts between the FW-UAS FE model and targets (deformable flat plate, rigid flat plate, and rigid knife-edge) were performed as stability checks. The FW-UAS FE model developed in this work facilitated the evaluation of the severity of FW-UAS mid-air collision to commercial and business jet airframes performed at and in conjunction with National Institute for Aviation Research. A series of worst-case scenarios involving impacts between the FW-UAS and commercial narrow-body transport and business jet airframes were simulated. For each simulated impact, an impact severity index value was assigned to characterize the relative threat to a given aircraft. In addition, a UAS frangibility study was performed to assess key UAS design features that result in reduced damage to target air vehicles. A “pusher” engine configuration was modeled where the high-density motor is located aft of the UAS’s forward fuselage. Positioning the high-density motor in the aft fuselage played an important role in reducing the impact damage severity.

Most studies on blast explosion focus on a single technique or software. This Thesis directly compares several methods of simulating blast loads using LS-DYNA, ABAQUS and CTH software. The techniques appraised in this thesis include; Jones-Wilkins-Lee (JWL) equation of state (EOS), spherical incident wave formulation, and a direct planar blast load application. In the first section of this study, we analyzed a free air-blast generated by detonating 100 g of composition-4 (C-4). Next, we placed and examined the lower extremity model under the same blast parameters in different coupled and uncoupled scenarios. In the free air-blast study, all three codes gave similar results. The peak over pressure from ABAQUS was the closest in value to the experimentally measured data. In the second section, the JWL EOS method consistently produced higher-pressure response in the lower extremity elements compared to the other methods implemented.

Motor vehicles collisions and falls have gradually increase the risk for spinal cord injuries. An increased knowledge of the spinal behavior and its injury mechanisms can be used as preventive strategies. Total Human Model for Safety (THUMS) SAFER is used as a tool for injury prevention, however, there is a lack of studies that evaluate the spinal cord injuries. The aim of this thesis is to implement a cervical spinal cord into the THUMS model. The mesh element quality was modified and the spinal cord was further adjusted for a correct insertion into the THUMS. The strain of the posterior and anterior surface of the cervical spinal cord during a head flexion were analyzed against experiments. Subsequently, a comparison of the head kinematics in frontal collision of the THUMS with and without the cervical spinal cord was performed. A refinement of the mesh element quality for a suitable computational time was achieved. The strain evaluation of the the spinal cord showed the same behavior as in the experiment for the posterior surface but the results were contradictory for the anterior surface. The results of the head kinematics with and without spinal cord showed no good correlation with the experimental data. Moreover, the models exhibited a bigger difference between them during the extension of the head than flexion. A further improvement of the mesh element quality required smaller element size. Nonetheless, it is important to consider that computational time increases with a decrease of element size. Several factors were critical for the strain comparison, such as the lack of information for the calculation of the strain. The difference in head kinematics from the experiment may be due to the material properties of the neck skin and the lack of the active muscles. Moreover, the contact constraints in the model may result in the differences between the THUMS models. In general, the spinal cord has been refined to obtain a favorable computational time. The evaluations have indicated that further modifications in the neck skin and contact constraints are needed for a better resemblance with the human body. Likewise, further validations against experimental studies are suggested.

No description available.

No description available.

No description available.

Ultra-high performance fiber-reinforced concrete (UHPFRC) is an advanced cement-based composite with enhanced compressive strength, tensile resistance and toughness when compared to conventional concrete. Interest in the application of UHPFRC as a retrofit material has been rapidly increasing, and a few existing studies have examined the ability of UHPFRC to retrofit and strengthen existing reinforced concrete (RC) structures under static loading; however, very limited studies have examined the effectiveness of UHPFRC to improve the response of RC members under blast loading. This thesis aims at filing this research gap and investigates the behavior of UHPFRC retrofitted RC flexural members under both static and blast loads. A total of twenty-one (21) specimens, in two different series are tested. Series 1 includes nine (9) singly-reinforced beams built with high-strength concrete (HSC) and strengthened by UHPFRC to improve shear and flexural behaviour. Series 2 includes a further twelve (12) doubly-reinforced beams/columns built with normal-strength concrete (NSC), and strengthened by UHPFRC to improve response under blast, or combined blast-axial loading. Various test parameters are examined including the effects of varying retrofit types (full jacket, U-jacket or T-sided), surface roughening methods, longitudinal steel reinforcement ratio, single vs. repeated blasts, and the effects of axial loading. The results from this thesis are presented in six journal articles. Papers 1 and 2 study the effects of UHPFRC jacketing on the static and blast behaviour of the singly-reinforced HSC beams in Series 1, while Paper 3 discusses the effects of additional parameters such as: the effect of retrofit type, roughening method and steel detailing on blast behaviour. Under static loading (Paper 1), the UHPFRC jacketing was found to be effective in increasing shear resistance (by preventing shear failure), and improving flexural behaviour (by increasing strength, stiffness, ductility and overall toughness) when compared to control beams built without UHPFRC. Similarly, under blast loads (Paper 2) the use of UHPFRC jacketing prevented shear failure, and improved flexural behaviour by reducing displacements at equivalent blasts, increasing overall blast capacity, and improving damage tolerance. On the other hand, the results show that UHPFRC-retrofitted beams with low longitudinal steel ratios may be vulnerable to brittle bar fracture failures. As part of the numerical research, finite element (FE) modelling is used to predict the static and blast behaviour of the test beams using software LS-DYNA (Papers 1 and 2). The results from Paper 3, provide further insights into the effects of retrofit type (FJ, UJ and T) and roughening method on blast performance; both the UJ and FJ retrofits were found to be effective in increasing shear resistance, reducing blast-displacements and increasing blast capacity, while the benefit of the T-sided retrofit was limited by the crushing capacity of HSC concrete. The effect of roughening method was found to be negligible, except at the very late stages of blast loading. Papers 4, 5 and 6 present the experimental results from the doubly-reinforced NSC beams tested in Series 2, with a focus on the effect of UHPFRC jacketing, UHPFRC retrofitting type and Axial loading, respectively. Paper 4 shows that the UHPFRC jacketing increased the stiffness and strength of the beams under both static and blast loading, however the high bond capacity of the UHPFRC and relatively low tension steel ratio increased the vulnerability of bar rupture failure. The numerical parametric study investigates the effects of steel ratio and blast load scenario, jacket thickness and interface location on blast performance and failure model. Paper 5 confirms that the blast performance of the beams is influenced by the retrofit type, with optimal performance obtained when using full- or U-jacketing. The efficient use of localized "hinge" retrofits was also found to be effective, and reduced the vulnerability to bar rupture. The numerical parametric study investigates the effects of steel ratio and blast load scenario (single vs. repeated) on the blast performance of the beams. Paper 6, studies the effect of UHPFRC jacketing in columns tested under combined axial and blast loading. The retrofit is shown to increase blast capacity and reduce blast-induced displacements and damage, though the final failure of the columns was governed by bar rupture. As part of the numerical parametric study the effects of axial load ratio, boundary conditions, steel ratio, jacket thickness and jacket design are studied numerically and found to have significant effects on blast behaviour and failure mode.