In golf, a range of shot types are necessary for successful performance, with driving and iron-play constituting the long-game. It is possible to vary long-game shots through altered trajectory, for example, by utilising right-to-left or left-to-right ball flight curvature, providing course management advantages. However, how golfers vary their biomechanics to achieve different trajectories is not scientifically understood. Therefore, the purpose of this thesis was to biomechanically investigate different trajectories hit with the same club. To investigate shot trajectories, accurate measures of performance were necessary. Launch monitors (TrackMan Pro IIIe and Foresight GC2+HMT) are bespoke technologies capable of tracking the clubhead and ball through impact. However, their accuracy for scientific research has not been independently validated. Therefore, a novel purpose-designed tracking method was developed using a three-dimensional optical tracking system (GOM). The accuracy of this method was validated and the system used as the benchmark to which the two launch monitors were compared through limits of agreement. The results showed, in general, the launch monitors were in closer agreement to the benchmark for ball parameters than clubhead. High levels of agreement were found for ball velocity, ball path, total spin rate and backspin. However, poorer agreement was shown for ball sidespin and spin axis as well as clubhead velocity, clubhead path and clubhead orientation. Consequently, the launch monitors were deemed unsuitable for inclusion in scientific research across a range of impact parameters. Draw and fade trajectories with a driver and draw, fade and low trajectories with a 5-iron were investigated biomechanically. The clubhead and ball were tracked using the optical method developed in this thesis. Key biomechanical variables (address position and whole-swing) were defined based on coaching theory. Statistically, analysis of variance (address) and principal components analysis (whole-swing), were used to compare draw against fade and low against natural trajectories. Multivariate correlation was used to identify swing pattern similarities between golfers. The group-level comparison showed draw-fade address differences whereby for draw trajectories, the ball was positioned further away from the target, the lead hand further towards the target and the pelvis, thorax and stance openness closed relative to the target line. Over the whole-swing, the draw when compared to the fade demonstrated a pelvis rotation, more rotated away from the target with later rotation; lumbar forward flexion, with slower extending in the downswing; lumbar lateral flexion, with more flexion towards the trail throughout and prolonged trail flexing through ball contact; thorax lateral flexion, with greater, slower lead flexing in the backswing and greater, more prolonged trail flexing in the downswing; pelvis translation further towards the target throughout, with earlier forward translation and centre of pressure, with an earlier, quicker, greater forward shift. Cluster differences were evident, with both Clusters I (57% of golfers with the driver) and II (71% of golfers with the 5-iron) showing greater, earlier thorax rotation towards the target and a tendency for greater lumbar forward flexion over the whole-swing (Cluster II) and backswing (Cluster I). For the group-level low-natural comparison, golfers positioned the ball further away from the target and their lead hand further towards the target for low trajectories. Further, Cluster IV (45% of golfers), narrowed their stance width and laterally flexed their thorax towards the lead, for the same trajectories. Over the whole-swing, the low when compared to the natural showed the pelvis translated towards the target throughout, with later, lesser forward shift for the low trajectories. Furthermore, centre of pressure displayed a greater forward shift for the same shots. Finally, both clusters (Cluster III 36% of golfers and Cluster IV) differed in lumbar forward flexion when playing low trajectories; over the backswing, Cluster III extended, whereas Cluster IV flexed. Cluster IV also showed greater extending in the downswing. Finally, Cluster IV showed more lumbar lateral flexion towards the lead throughout. The results of this study have implications for scientific researchers as well as golf coaches, club-fitters and professionals. Commercially available launch monitors appear accurate enough for coaching applications, however caution is needed for scientific research when tracking a range of clubhead and ball parameters. Furthermore, changes in biomechanics when playing different trajectories has implications for future research and interpretation of published work, as well as for coaching theory. Future work following this thesis could utilise the optical tracking method to validate further commercial systems and for more detailed experimental investigation of clubhead-ball impacts. Furthermore, additional biomechanical investigation into a wider range of shot trajectories across more variables could be conducted, with a more in-depth understanding gained from principal components analysis and golfer clustering.

Dynamic response of materials to high-speed and high-intensity loading conditions is important in several applications including high-speed flows with droplets, bubbles and particles, and hyper-velocity impact and penetration processes. In such high-pressure physics problems, simulations encounter challenges associated with the treatment of material interfaces, particularly when strong nonlinear waves like shock and detonation waves impinge upon them. To simulate such complicated interfacial dynamics problems, a fixed Cartesian grid approach in conjunction with levelset interface tracking is attractive. In this regard, a sharp interface Cartesian grid-based, Ghost Fluid Method (GFM) is developed for resolving embedded fluid, elasto-plastic solid and rigid (solid) objects in hyper-velocity impact and high-intensity shock loaded environment. The embedded boundaries are tracked and represented by virtue of the level set interface tracking technique. The evolving multi-material interface and the flow are coupled by meticulously enforcing the boundary conditions and jump relations at the interface. In addition, a tree-based Local Mesh Refinement scheme is employed to efficiently resolve the desired physics. The framework developed is generic and is applicable to interfaces separating a wide range of materials and for a broad spectrum of speeds of interaction (O(km/s)). The wide repertoire of problems solved in this work demonstrates the flexibility, stability and robustness of the method in accurately capturing the dynamics of the embedded interface. Shocks interacting with large ensembles of particles are also computed.

<p>When a composite laminate is transversely impacted by a projectile at the ballistic limit, its failure mode transits from global conical deformation to localized perforation. This Ph.D. dissertation aims to reveal the fundamental material failure mechanism at the ballistic limit to control perforation. First, transverse impact experiments were designed on composite strips to isolate the interaction between plies and tows. Three failure modes were identified, divided by no, partial, and complete failure before the transverse wave deformed the entire composite strip. The failure phenomenon and critical velocity region can differ with the fiber type and projectile nose geometry and dimension. In most impact events, the composite strips all failed in tension in the front of the projectiles, although they failed at different positions as the projectile nose geometry and fiber type changed. A special failure phenomenon was uncovered when the composite strips were impacted onto razor blades above the upper limit of the critical velocity region: the composite strips seemed to be cut through completely by the razor blades. To further investigate the failure by razor blade, a microscopic method was developed to cut a single fiber extracted from the composite strip and simultaneously image the failure process inside a Scanning Electron Microscope (SEM). The experiments revealed that the razor blade cannot cut through the inorganic S-2 glass fibers while can partially incision the aramid Kevlar^®KM2 Plus fibers and completely shear through the ultra-high-molecular-weight polyethylene (UHMWPE) Dyneema^® SK76 fibers. Further investigations on the fiber’s failure under dynamic cut revealed that there was no variation in the failure mode when the cut speed was increased from 1.67 μm/s to ~5.34 m/s. To record the local dynamic failure inside the composite strips and single fibers at high-velocity impact, an advanced imaging technique, high-speed synchrotron X-ray phase-contrast imaging, was introduced, which allows to capture the composite’s internal failure with a resolution of up to 1.6 μm/pixel and at a time interval 0.1 μs. Integrated with a reverse impact technique, such an advanced imaging technique is believed to be capable of revealing the mechanism involved in the impact-induced cut in single fibers, yarns, and composite strips. The relevant studies will be the extended work of this Ph.D. dissertation and published in the future.</p>

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The main purpose of this thesis is the systematic, experimental investigation of how a soft interlayer affects the impact response and energy dissipation mechanisms of all-polymer multi-laminates. An instrumented, intermediate impact velocity experimental setup with strain rates on the order of 100 s-1, is used to assess the impact mechanics of three-layered samples consisting of a poly(methyl methacrylate) (PMMA) front, polymer interlayer or adhesive, and polycarbonate (PC) back layer. Instrumentation of the gas gun is achieved with a shock accelerometer measuring contact force and optical displacement sensors recording deflection. Previous impact research utilizing instrumented gas guns by Levy and Goldsmith, and Delfosse et al. have measured contact force, but did not record simultaneous out-of-plane displacement. Signals acquired are temporally aligned allowing for insight into the response of the multi-laminate during impact, which is inaccessible with typical gas guns. Impact testing is completed on bonded and unbonded sample configurations, with two thermoplastic polyurethane and four polyacrylate interlayers. Quantitative metrics from force and displacement signals, along with post-impact damage observations, are used to compare impact performance between configurations and impact velocities (12 and 22 m/s). In general, the presence and bonding of an interlayer increases impact resistance by mitigating and localizing the impact load. The interlayers are characterized at various strain rates in tension, compression, and shear adhesion. In tension, all interlayers display rate dependence, non-linearity, and hysteretic behavior showing varying degrees of increasing energy dissipation with strain rate. Several trends between sample fracture and energy absorption mechanisms, quasi-static and low rate interlayer response, and metric results are established and discussed. / Master of Science

Sound generated by impacting structures is of considerable importance in noise control. Sound is generated by a vibrating structure by inducing pressure fluctuations in the surrounding medium. Impact induced noise is the sound generated by a vibrating structure subjected to motion constraint. In such problems one has to study the vibration behavior of the oscillator, the impact mechanics, and the emanating acoustic field dynamics. A literature review carried out points to the fact that though there has been considerable work on vibration behavior of impact oscillators and the acoustics of impact of rigid masses, there is very little work reported on the sound generated due to vibration and impact. This thesis couples vibration analysis of oscillators undergoing impact with its acoustic behavior. The vibration behavior is nonlinear on account of the impact. Therefore the vibration analysis as well as the resulting acoustic field analysis has to be in the time-domain. This investigation is concerned with the effect of structural dynamics, impact dynamics, and acoustic field boundary conditions, on the sound pressure generated due to vibration and impact. We have considered a single degree of freedom as well as a flexible Euler-Bernoulli beam vibration model. The former is the simplest for studying vibro-acoustic response. The numerical model of the beam is derived using the finite element method resulting in a finite dimensional system with more than one degree of freedom. The dynamics of each degree of freedom are distinct in terms of amplitude and phase and are a function of the nature of linear dependence on other degrees of freedom and the nature of excitation. An impacting beam introduces interesting interactions between the dynamics of the degrees of freedom as a consequence of nonlinearity due to the motion constraint. The impact of the oscillator mass with a barrier is modeled using a simple coefficient of restitution model based on Hertzian contact theory. There is velocity reversal on contact with the barrier. The contact force is finite acting within a finite interval of time. The contact force is assumed to vary in time during the contact interval. This effectively models contact as linearly elastic. The pressure perturbation due to vibration of the oscillator mass is shown equivalent to the pressure perturbation due to an acoustic dipole. The acoustic dipole is placed at the equilibrium position of the vibrating mass. The dipole pressure is then a function of motion of the oscillator. In the case of a single degree of freedom oscillator the dipole axis is along the direction of motion. The sound pressure due to a vibrating beam is modeled as an array of acoustic dipoles placed at the finite element nodes of the beam and stationary at the beam's static equilibrium configuration. The dipole axis is once again aligned with the direction of vibration of the beam that is transverse to the beam neutral axis. Anechoic as well as perfectly reflecting acoustic boundary conditions are simulated in the time-domain. The resulting governing equation of motion of the single degree freedom oscillator as well as the beam are integrated numerically in time to compute its response. The acoustic pressure is shown to be critically dependent on the excitation frequency of the oscillator, dynamic properties of the oscillator, coefficient of restitution of impact and impact dynamics, and acoustic field boundary conditions.

With over 830,000 km of operating pipeline in Canada alone, their safe and continued functioning underpins much of daily life. A key type of risk associated with pipelines is third-party damage, damage caused by actions not associated with the pipelines normal operation. The question of whether the pressurized structure like pipeline or pressure vessel would undergo “unzipping” due to the third-party impact is crucial for the safety of pipelines or pressure vessels in service needs to be answered. Thus, we endeavour to develop a methodology for assessment of design solutions effectiveness to prevent a pipeline or pressure vessel failure in an abrupt explosion-like fashion due to third-party damage. Model of crack propagation determining whether the “unzipping” rupture will occur is viewed as a key element in the safety-driven design procedure providing significant effect on the safety of operation. The crack propagation modeling is achieved through the use of nonlinear fracture mechanics technique. The method of singular integral equations is used to calculate the critical stress required for the catastrophic failure of pipeline or pressure vessel damaged due to third-party interference. The model was implemented as a FORTRAN program. Testing of the developed numerical tool was performed using experimental data available in the literature, with the results showing promising agreement. / February 2016