This project is centred on an ongoing trailer component failure problem at the STEELBRO New Zealand Ltd due to cracks. In this research the problem has been systematically approached using ANSYS finite element analysis software. The approach involves investigation of the problem and structural analysis of the trailer subjected to two types of service conditions. The service conditions are simulated in ANSYS which involved CAD and finite element modelling of the trailer, and then the finite element model is validated experimentally by strain gauges and geometrically by ANSYS element shape checking capability. The finite element model subjected to static structural analysis confirmed the crack locations and indicated the cause of the failure. Further fatigue analysis on one of the loading condition revealed it’s potential to cause failure at the crack locations. Finally, this research concludes with a proposal of revised component design to overcome the failure at the crack locations and recommendations for further analysis on the trailer.

This thesis work is based on the analysis of a fan blade attachment whereby a complete 3D model is presented by a partner company. The acceptability of a new design regarding the mechanical loads consisting of dividing the hub into two parts instead of using a solid hub is studied. From the model some critical parameters for the attachment of the blade with respect to the stresses are chosen such as the rotational speed, fillet size of the blade and the neck size of the blade. Parametric studies of these parameters are carried out in order to suggest the new design. Bearing in mind that a safety factor of 2 is the prerequisite, based on the analysis performed on ANSYS Workbench, it is suggested from the preliminary design that the axial fan can operate in two specific scenarios consisting of a rotational speed of 1771 rpm and a rotational speed of 1594 rpm. Using this set of parameters, a suggestion is drawn up on the blade fillet which will give lower stress. Blade fillet size of 30 to 35mm is recommended while a size of 45mm is recommended on the neck of the blade. A modal analysis is performed in order to find at what frequency will the model be vibrating and a lowest and critical frequency of 16.8 Hz is obtained. Finally, a fatigue analysis of some interesting areas is performed in order to determine the numbers of cycles before fatigue failure occur. It is recommended to use the rotational speed since these speeds have offered a High Cycle Fatigue results.

A chassis is known as the carrying unit of an automobile, like the engine, transmission shaft and other parts are mounted on it. Ladder chassis has longitudinal rails which are connected along the length with crossmembers through welding or mechanical fasteners. Rectangular box section is chosen for the longitudinal rails of ladder chassis. Design modifications are done in HyperMesh to improve torsional and bending stiffness of the chassis designed in steel and CFRP. Adding of the X- bracing cross-member and ribs are few of the techniques used to provide strength to chassis. This thesis aims to produce a light-weight chassis. A combination chassis of both steel and CFRP components is created by replacing heavy steel cross-members with CFRP cross-members, which resulted in the reduction of weight by 14.6%. Crash analysis is performed to all the chassis using Radioss. Depending on the result obtained from crash analysis and values of torsional and bending stiffness, the combination chassis is selected. Thickness optimization is performed to the combination chassis. It is observed that 7.91% of weight is further reduced in the combination chassis.

Underground mining equipment is required by the Mine Safety and Health Administration to have certified overhead protective structure, referred to here as a canopy. By reviewing previous works in the area of protective canopies and utilizing their findings to

The atomic force microscopy (AFM) has been widely used for the investigation of the surface topography and high precision force measurements at the nano-scale. Researchers have utilized AFM to quantify the viscosity of the cell membrane in the vertical direction, which is a primary indicator of a cell's functionality and health condition. A modified lateral force microscopy (LFM) to quantify viscosity through lateral force measurements applied on the sidewall of cell membranes. The resulting twist of the cantilever in mLFM is induced by the contact between sidewalls of the tip and features on the sample. However, the measurement sensitivity of the mLFM requires improvement. This thesis focused on optimizing probe geometries and materials to improve the measurement sensitivity. <div>Probes (cantilevers and tips) with different geometries and materials properties were proposed and their deformations in the mLFM force measurement were studied. The force measurement process, in which the tip contacted the sidewall of control samples, including a hard sample and a soft sample, was modeled by finite element analysis (FEA). This study calculated torsional spring constants and measurement sensitivities according to the data produced from FEA. The impact of various geometric parameters on the torsional spring constant and measurement sensitivity were presented and discussed. The optimal probe configuration and material for measurement sensitivity was found from the parameters tested in this research. For the hard sample, the cantilever with a "T-shape" cross section and a tetrahedral tip made from graphite had optimum measurement sensitivity. For the soft sample, the cantilever with a "T-shape" cross section and a conical tip with a 600nm-radius sphere tip apex had the optimum measurement sensitivity. The reason for the difference in optimum probe combination for hard and soft sample was that the measurement sensitivity for hard sample was more susceptible to change in lever arm distance and measurement sensitivity for soft sample was more susceptible to the change in tip radius. The measurement sensitivity has been improved significantly on both hard sample and soft sample compared to a DNP V-shaped probe. </div>

Introduction: Unicompartmental knee replacements (UKRs) are an alternative to total knee replacements (TKRs) for treating isolated medial compartment knee osteoarthritis. However, revision rates are consistently higher than for TKR and UKRs are commonly revised for “unexplained” pain, a possible cause of which is elevated proximal tibial bone strain. The influence of implant design on this strain has not been previously investigated. Aims: The aims of this thesis are to determine the effect of medial UKR tibial component design on proximal tibial strain and ongoing pain. Methods: A retrospective clinical cohort study was performed comparing patient reported outcome and implant survival of a metal backed mobile bearing UKR implant (n=289) and an all-polyethylene (AP) fixed bearing UKR implant (n=111) with minimum 5 year follow up. A method of digital radiological densitometry, the greyscale ratio b (GSRb), was developed, validated and applied to plain radiographs to measure changes in bone density over 5 years in both the metal backed (n=173) and all-polyethylene (n=72) UKR patients. A finite element model (FEM) was validated against previous mechanical testing data and was used to analyse the effect of metal backing and implant thickness on proximal tibial cancellous bone strain in fixed bearing UKR implants. Results: There were no significant differences in patient reported outcomes between implants throughout follow up. Ten year all cause survival was 90.2 (95%CI 86-94) for the metal backed implant and 79.9 (60.7 to 99) for the all-polyethylene. Revision for unexplained pain was significantly greater in the AP implant where revisions were performed significantly earlier. Overall, the mean GSRb reduced following medial UKR with no difference between implants. In those patients where GSRb increased, patient reported outcomes were worse with an association with ongoing pain. A finite element model was successfully validated using acoustic emission and digital image correlation data. This model confirmed that the volume of cancellous bone exposed to compressive and tensile strains in excess of 3000 (pathological overloading) and 7000 (fracture) microstrain were higher in the AP implants, as were peak tensile and compressive strains. Varying polyethylene insert thickness did not affect these strain parameters in the metal backed implant, but varying polyethylene thickness in the AP implants had significant effects at all loads with elevated strains in thinner implants. Increasing the AP thickness to 10mm did not reduce strains to the levels found under metal backed implants, and imminent cancellous bone failure was implied when AP thickness was reduced to 6mm. Conclusion: UKRs with all-polyethylene tibial components are associated with greater proximal tibial strains than metal backed implants and this is exacerbated in thinner implants. The clinical consequences of this are uncertain. Medial UKR implantation does alter proximal tibial GSRb, though this is not uniform and is independent of implant type. When GSRb increases it is associated with ongoing pain.

The objective of this research was to develop and verify a mathematical model and the necessary material database that allow predicting the physical and material property changes that occur in aluminum casting alloys in response to precipitation-hardening heat treatment. The model accounts for all three steps of the typical precipitation hardening heat treatment; i.e., the solutionizing, quenching, and aging steps; and it allows predicting the local hardness and tensile strength, and the local residual stresses, distortion and dimensional changes that develop in the cast component during each step of the heat treatment process. The model uses commercially available finite element software and an extensive database that was developed specifically for the aluminum alloy under consideration - namely A356.2 casting alloy. The database includes the mechanical, physical, and thermal properties of the alloy all as functions of temperature. The model predictions were compared to measurements made on commercial cast components that were heat treated according to standard heat treatment protocols and the model predictions were found to be in good agreement with the measurements.

Every year, millions of people are killed or injured in motor vehicle accidents in the United States. Although recent improvements to occupant restraint systems, such as seatbelts and airbags, have significantly decreased life threatening injuries, which usually occur to the chest or head, they have done little to decrease the occurrence of lower extremity injuries. Although lower extremity injuries are not usually life threatening, they can result in chronic disability and high psychosocial cost. Of all lower extremity injuries, injuries to the knee-thigh-hip (KTH) region have been shown to be among the most debilitating. This project used a finite element (FE) model of the KTH region to study injury. A parametric investigation was conducted where the FE KTH was simulated as a vehicle occupant positioned to a range of pre-crash driving postures. The results indicate that foot contact force and knee kinematics during impact affects the axial force absorbed by the KTH region and the likelihood of injury. The results of the study could be used to reevaluate the lower extremity injury thresholds currently used to regulate vehicle safety standards. Also, the results could be used to provide guidelines to vehicle manufacturers for developing safer occupant compartments.

"Recent full-scale crash tests of the weak-post W-beam guardrail system have resulted in unsatisfactory collision performance as evaluated by the National Cooperative Highway Research Program (NCHRP) Report 350. Since acceptable crash test performance is required in order to use a guardrail on a Federal-Aid Highway in the United States, the poor performance of the weak-post W-beam guardrail is a significant problem to those states that use it. The goal of this project was to improve the impact performance of the weak-post W-beam guardrail system so that it satisfies the requirements of NCHRP Report 350 at test level three."

An emerging demand for the precise manipulation of cells and microparticles for applications in cell biology and analytical chemistry has driven recent development of ultrasonic manipulation technology. Compared to the other major technologies used for cell and particle manipulation, such as magnetic tweezing, optical tweezing and dielectrophoresis, ultrasonic manipulation has shown excellent capabilities and flexibility in a variety of applications with its advantages of versatile, inexpensive and easy integration into microfluidic systems, maintenance of cell viability, and generation of sufficient forces to handle cells with dimensions up to tens of microns and agglomerates of a large number of cells. This thesis reviews current state-of-the-art of ultrasonic manipulation technology and reports the development of various ultrasonic manipulation devices, including simple devices integrated with high frequency (&gt; 20 MHz) ultrasonic transducers for the investigation of biological cells and complex ultrasonic transducer array systems to explore the feasibility of electronically controlled 2-D and 3-D manipulation. Piezoelectric and passive materials, fabrication techniques, characterisation methods and possible applications are discussed. The behaviour and performance of the devices have been investigated and predicted in virtual prototyping with computer simulations, and verified experimentally. Issues associated during the development are highlighted and discussed. To assist long term practical adoption, approaches to low-cost, wafer level batch-production and commercialisation potential are also addressed.