Most uncemented total hip replacements (THR) rely on press-fit for the initial stability and thus lead to the secondary fixation which is biological fixation. Choosing the accurate interference fit may have a great effect on implant stability and implant loosening prevention. Implant loosening is the most reported problem where it leads the increasing of micromotion at the bone-implant interface due to insufficient primary fixation. By having sufficient stability or fixation after surgery, minimal relative motion between the prosthesis and bone interfaces allows osseointegration to occur. Therefore, it will provide a strong prosthesis-to-bone biological attachment. The aim of this study was to evaluate the effect of bone-implant interface for uncemented hip implant. In this study, a three-dimensional model of hip implant was designed and analysed by using commercial Finite Element Software namely, ANSYS WORKBENCH V15 software in order to investigate the bone-implant interface effect using the chosen implant design. The value of interference fit (δ= 0.01, 0.05, 0.10 and 0.50 mm) and coefficient of friction (δ= 0.15, 0.40 and 1.00) were used to simulate the bone-implant interface. It was found that the interference fit of 0.50 mm was sufficient to achieve the primary fixation and also the best fitting; thus, the implant loosening can be minimized. The interference fit of 0.50 mm was the minimal value to achieve fixation, while the coefficient of friction did not affect the bone-implant interface.
This research was conducted to provide a feasible method for reconstructing the 3D model of mandibular bone to undergo finite element analysis to investigate von Mises stress, deformation and shear stress located at the cortical bone, cancellous one and neck implant of the proposed dental implant design. Dental implant has become a significant remedial approach but although the success rate is high, the fixture failure may happen when there are insufficient host tissues to initiate and sustain the osseointegration. Computerised Tomography scan was conducted to generate head images for bone reconstruction process. MIMICS software and 3-matic software were used to develop the 3D mandibular model. The reconstructed mandibular model was then assembled with five different 3D models of dental implants. Feasible boundary conditions and material properties were assigned to the developed muscle areas and joints. The highest performance design with the best responses was the design B with the value for the von Mises stress for the neck implant, cortical and cancellous bone were 7.53 MPa, 16.91 MPa and 1.34 MPa respectively. The values for the maximum of micromotion for the neck implant, cortical and cancellous bone of design B were 20.60 μm, 21.17 μm and 5.83 μm respectively. Shear stress for neck implant, cortical and cancellous bone for this design were 0.15 MPa, 4.74 MPa and 1.54 MPa respectively. The design with a cone shaped hole which is design B was the proper design when compared with other designs in terms of von Misses stress, deformations and shear stress.
Surface topography and morphological behaviours are the important aspects in the application of surface bearing as it deals with the contact area of objects upon motion. Improved surface bearing will be set as an indicator for tribology behaviour to reduce the possibility of wear rate and reduce the friction of objects, respectively. Thus, in this study, the fundamental of micro bearing concept was imparted as the Ultra High Molecular Weight Polyethylene (UHMWPE), which is a low density filler, will float onto the surface of the composite system to become a solid lubricant upon curing. UHMWPE filler, which is commonly known for its dominant properties of high tendency to resist wear and has low coefficient of friction were fabricated alongside epoxy resin in the composite system to achieve the desired strength and durability to perform over time. However, there are limitations of UHMWPE during processing upon the dispersion of the fillers with the matrix particles due to epoxy resin that has relatively high in viscosity. Therefore, acetone has been selected as a diluent with ratio of 1:1/4, 1:1/3, 1:1/2, 1:1 to dilute the high viscosity epoxy resin. The surface profile measurement were examined using Alicona Infinite Focus and Polarized Optical Microscope. Based on the results observed, EpUPE3 (epoxy and UHMWPE with acetone ratio of 1:1/2) showed better surface distribution and morphology with relatively low value of surface roughness (Ra) which is 1.41 µm and low pseuodocolour value of surface height which is around 6.76-6.77 cm compared to other formulation ratio. In near future, these surface topography and morphological analysis are important to relate with tribological, physical and mechanical properties of the micro bearing layers for bearing applications, specifically.
External fixator has played an important role in repairing fractured ankle bone. This surgery is done due to the several factors which are the bone is not normal position or has broken into several pieces. The external fixator will help the broken bone to grow and remodel back to the original appearance. However, there are some issues regarding to the stability of this fixation. Improper design and material are the major factor that decreased the stability since it is related to the deformation of the external fixator to hold the bone fracture area. This study aims to design a stable structure for constructing delta frame ankle external fixator to increase the stability of the fixation. There are two designs of external fixator with two types of material used in this present study. Both external fixators with different materials are analyzed in terms of von Mises stress and deformation by using a conventional Finite Element Analysis software; ANSYS Workbench V15. The result obtained shows the Model 1 with stainless steel has less stress and deformation distributions compared to the Model 2. Hence, by using Model 1 as the external fixator, the stability of the fixation can be increased.
Bamboo is well known as the oldest structural material that possess unique anatomical structure and superior mechanical properties. It has become a subject of interest worldwide and research is being conducted for its structural applications including safety, durability and also mechanical properties. Many studies carried out previously indeed have shown superior strength of bamboo. Most of the research circulate on the mechanical properties improvement using chemical, plasma, enzyme, fungi and nanocellulose coating treatment. However, despite the conventional treatments’ advantages, but they are impractical, costly and it able to change the structure of the treated materials. This study aims to evaluate the morphological properties of untreated and treated of Semantan bamboo culm (Gigantochloa scortechinii) after subjected to a simple and cost-effective epoxy treatment. By using Alicona Infinite Focus 3D profilometer machine, the comparison between the untreated and treated surfaces of bamboo can be obtained under profile surface roughness test. Meanwhile, the depth formation of the treated surfaces also can be obtained by using the same machine under profile form management test. Next, optical microscope was used later to examine the epoxy matrix treatment formation of the untreated and treated bamboo surfaces. The result revealed that the application of epoxy treatment gave a better surface roughness and structure as it treat the bamboo strips and concurrently gave a thin layer of coating to the bamboo strips. The findings of this study suggest that epoxy treatment can be an effective and economical approach to treat natural fiber as it resulting in good surface structure which simultaneously increase the chemical and mechanical interlocking; thus, the bond between matrix and natural fiber become stronger.
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