The investigation contained herein is a part of a larger, long-term project: The Development of SMART Aircraft Bolts. Structural failures, at highly stressed components, arc common in some of the aircraft used by the South African Air force. The strength of one such component, the wing bolts on the C-130 aircraft, is analysed and compared to the stress distribution in a bolt which has a small hole drilled through the centre of the bolt (which will be used to insert a sensing device). The results of this analysis will be used as input into further phases of the project, e.g., SMART material selection and the development of sensing devices. Due to the complex physics of a bolted joint, advanced analysis of the bolt under conservative loading was performed, after conducting thorough research into bolted joint design and analysis methods, in order to provoke the final recommendations. / Thesis (M.Sc.)-University of Natal, Durban, 2000.

Aviation is known to have some of the most stringent structural health monitoring standards in the world. An example of this would be the fact that certain bolts in the aircraft assembly must be periodically removed and inspected for fatigue damage. This can be a very costly endeavour: a case in point being the Hercules C130 aircraft, which requires approximately 200 man hours of down-time for the inspection of the bolts that attach the wings to the fuselage. The substitution of TRIP (Transformation Induced Plasticity) steel bolts for the current HSLA steel (AISI 4340) from which the bolts are manufactured, allows the bolt to act in the capacity of load bearing member as well as damage detector. This unique feature is a consequence of the transformation characteristic exhibited by TRIP steels when they are strained: an irreversible change within their microstructure from paramagnetic austenite parent phase to permanent ferromagnetic state occurs in direct proportion to the peak strain. This property allows us to establish a relationship from which the service life of the component can be determined. A prototype of a smart aircraft bolt and washer system has been developed, where the bolt acts as damage detector and the washer effectively examines the health of the bolt by reading the changing magnetic susceptibility of the bolt. This study presents both material development and product development phases of the Smart Aircraft Bolt prototype. A prediction of transformation characteristic due to deformation is carried out using finite element analysis (mechanical model) and a constitutive model (strain induced martensitic transformation kinetics) to predict the best situation for the smart washer. In addition, experimental work is performed in the form of cyclic temperature testing (with and without external loading) and tension-tension fatigue testing. For both sets of experimental testing, two positions of washer placement are tested. A correlation between volume fraction of martensite present and remaining life, is therefore possible. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2008.

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No description available.

No description available.

Ground contact results in the generation of a heel-strike transient that propagates through the musculoskeletal system. The inability to attenuate the heel-strike-induced shock wave is a possible factor in the development of various gait pathologies and overuse-type injuries, such as knee osteoarthrosis, stress fractures, and low back pain. It is hypothesized that prolonged running will result in increased shock transmission at the tibia and sacroiliac joint during conditions of controlled velocity/stride mechanics. Subjects performed an extended running trial for 25-minutes at 75% HRReserve. EMG data of the vastus medialis, vastus lateralis, and tibialis anterior and accelerometer data from the tibial tuberosity and sacrum were recorded at one-minute intervals. Accelerometer data at the tibial tuberosity did show a significant increase during the run protocol. Linear regression of EMG frequency and tibial shock also demonstrated a significant relationship. An extended running protocol will lead to increases in tibia shock acceleration independent of stride mechanics. / School of Physical Education

The purpose of this study was to compare the protective characteristics of four different ankle braces and one form of ankle taping. An inversion and plantar flexion platform was used to induce ankle movements. The subjects used in this study consisted of 10 volunteer male students. The subjects had no sprains five months prior to testing. All subjects were tested in the same size 10 shoes, high tops and low tops. A Certified Athletic Trainer applied all ankle braces and ankle tapings. A closed basketweave with heel locks, adherent spray, and pre-wrap was used for all taping conditions.After the application of the ankle braces or taping, each subject performed two tests on the inversion and plantar flexion platform. A random order was used among the subjects. An ankle inversion platform was modified to induce 30 degrees of inversion and 35 degrees of plantar flexion simultaneously. The subjects will be filmed using a Locam 16mm at 200 frame/second. All subjects were filmed from the posterior plane with markings on the posterior aspect of the lower leg to help analyze the movement at the subtalar joint. A Calcomp 9100 series digitizer that was interfaced with a VAX computer was used to analyze the data and calculate the amount of angular displacement at the subtalar joint. An ANOVA with repeated measures was used to determine significant differences between support techniques. University procedures for the protection of human subjects was followed. ANOVA procedures indicated no significant difference in angular displacement between braces. A statistical analysis indicated that low top shoes provided significantly more support than high top shoes in braced ankles. / School of Physical Education

In the past few years, some experimental investigations have been conducted to verify seismic behaviour of fiber reinforced polymer reinforced concrete (FRP-RC) beam-column joints. Those researches were mainly focused on exterior beam-column joints without lateral beams. However, lateral beams, commonly exist in buildings, can significantly improve seismic performance of the joints. Moreover, the way the longitudinal beam bars are anchored in the joint, either using headed-end or bent bars, was not adequately addressed. This study aims to fill these gaps and investigate the shear capacity of FRP-RC exterior beam-column joints confined with lateral beams, and the effect of beam reinforcement anchorage on their seismic behaviour. Six full-scale exterior beam-column joints were constructed and tested to failure under reversal cyclic loading. Test results showed that the presence of lateral beams significantly increased the shear capacity of the joints. Moreover, replacing bent bars with headed-end bars resulted in more ductile behaviour of the joints.

The effect of the element length is examined in modelling crack growth in fatigue loading of an adhesive joint. This is done for a cohesive element using an expression for the damage evolution developed at the University of Skövde which is implemented using the UMAT subroutine in the FE-solver Abaqus. These analyses are done for pure mode I loading by analysing a DCB-specimen loaded by a pure moment. An expression is developed in which the critical element length is dependent on the geometry of the specimen (in the form of the wave number of the adhesive joint), the element length, the material properties of the adhesive (in form of the material parameters , , ), the load applied (in form of the stress in the crack tip), the time step used in the analysis and the crack growth rate. It is shown that the results converge by decreasing the element length and the time step used. Therefore an expression for the crack growth rate as a function of the remaining parameters can be determined. Another expression is thereafter developed for the element length needed in order to get a crack growth rate within a certain range of the critical element length. The results show a regular pattern but are not monotone. Therefor two different definitions of the critical element length are tested, either by defining the critical element length as the point where the error is greater than an arbitrary boundary of 1 % of a converged result or where a least square approximation of the error is within 1 % of the converged results. The first method shows a highly irregular result which makes it difficult to develop an expression out of these results. The second method on the other hand gives results that are predictable enough to develop a function out of them. This is done using a regression analysis with all parameters of a third order expression in order to get an expression.

In the past few years, some experimental investigations have been conducted to verify seismic behaviour of fiber reinforced polymer reinforced concrete (FRP-RC) beam-column joints. Those researches were mainly focused on exterior beam-column joints without lateral beams. However, lateral beams, commonly exist in buildings, can significantly improve seismic performance of the joints. Moreover, the way the longitudinal beam bars are anchored in the joint, either using headed-end or bent bars, was not adequately addressed. This study aims to fill these gaps and investigate the shear capacity of FRP-RC exterior beam-column joints confined with lateral beams, and the effect of beam reinforcement anchorage on their seismic behaviour. Six full-scale exterior beam-column joints were constructed and tested to failure under reversal cyclic loading. Test results showed that the presence of lateral beams significantly increased the shear capacity of the joints. Moreover, replacing bent bars with headed-end bars resulted in more ductile behaviour of the joints.