Elastic Interactions of Osteon-Crack Penetration in Longitudinal Fracture

Longitudinal fracture of cortical bone involves complex elastic interaction between interstitial matrix, cement line, osteon and Haversian canal. Based on Kachanov theory of microcrack and hole interaction, there is effective impact interaction between different elastic moduli, and interaction between stress risers. This paper aims to numerically evaluate the effect of different Young’s modulus in osteonal system structure for four-phase constituents (anterior, posterior, medial and lateral) in Haversian bone system particularly in longitudinal crack direction. The interaction between single crack and Haversian canal in crack-osteon penetration process is analysed based on linear elastic fracture mechanics (LEFM) with plain strain condition. Stress interaction intensities are compared to Brown and Srawley empirical formulation. The simulation results showed that the elastic interaction before the osteon penetration is consistent and stable

Leg Length Inequality Effects on Ground and Lower Extremity Joint Reaction Forces during Walking

Leg length discrepancy (LLD) is caused either due to functional disorder or shortening of bone structure. This disorder could contribute to the significant effects on body weight distribution and lumbar scoliosis to a certain extent. Ground reaction force and joint reaction force are the parameters that can be used to analyse the responses in weight distribution and kinetics changes on the body joints, respectively. The purpose of this study was to determine the effect of Leg Length Discrepancy (LLD) on ground reaction force (GRF) and joint reaction force (JRF) in subjects mimicking LLD. Plywood block was used to mimic the artificial LLD. The height of the plywood was increased up to 4.0 cm with 0.5 cm increment. Hence, eight different height of LLD was considered to investigate which height of LLD initiated the significant effect. The experiment was conducted on ten healthy subjects that are walking on the force plate in two conditions; without load and with a load of 2 kg. Qualisys Track Manager (QTM) system and Visual 3D Software were employed for data processing. The result showed that mean peak vertical GRF and JRF of the shorter leg was found carried more weight than the longer leg during walking without load and walking with the additional load, respectively. Also, mean peak vertical GRF and JRF were found carried more weight during walking with additional load compared to walking without load

Modelling of patient-specific femur with osteogenesis imperfecta to determine the fracture risk under various loads

Osteogenesis imperfecta (OI) is a fragile bone disease characterized by easy fractures. The femur consists of cortical and cancellous bone, each with different mechanical properties. Bone fractures often occur throughout patients’ lifetime. However, doctors still have no quantitative method to predict fractures. Therefore, this project’s purpose is to investigate the OI femoral fracture risk to help prevent fractures. The project consists of three sections; cortical and cancellous segmentation, reconstruction of 3D OI femoral model and finite element analysis (FEA) of the OI femur to obtain fracture risk. The fracture risk in daily activities and the fracture load were examined. All the stress values were judged by the fracture criteria, assumed as 115 MPa. The exercises that exerted force more than 6 times of body weight can cause fractures. In addition, the optimal compressive force and tensile force were 919.7 N and 912.1 N, respectively, while medial and lateral impact were 230.8 N. Cancellous bone was not affected even a fracture happen. Based on these findings, we can conclude that when the OI femur is subjected to lateral or medial forces, the femur breaks easily. The bone can be reconstructed into a solid body without having to separate bone into cortical and cancellous

Microwave Reflection Based Dielectric Spectroscopy for Moisture Content in Melele Mango Fruit (Mangifera Indica L.)

The Melele mango is one of the special local fruit Malaysia and it has high commercial value. However, the current methods are not efficient in determining optimum period to harvest. The optimum harvest time has close relationship with moisture content in fruit. The reflection based dielectric spectroscopic technique is conducted to measure moisture in Melele mango fruits. Dielectric and reflection measurements were conducted over a frequency range from 200 MHz to 8 GHz on clone Melele mango. Dielectric constant, loss factor and complex reflection coefficient of Melele mango with different moisture content were measured using an Agilent E8362B PNA Network Analyzer in conjunction with an Agilent 85070E High Temperature Probe over a frequency range from 200 MHz to 8 GHz. The measured reflection coefficient is presented in magnitude and phase. Dielectric constant and loss factor decreases when the moisture content in mango fruit decreases. The magnitude of the reflection coefficient descends due to increment of the dielectric constant. The results show that the measured dielectric properties and complex reflection coefficient provides the ability to predict fruit moisture content

Kinematic Analysis of a Screw Wheeled Omnidirectional Mobile Robot

This paper presents a study of an omnidirectional mobile robot based on a screw wheels mechanism. A concept design of an omnidirectional mobile robot propelled by four screw wheels approach is introduced. The forward and inverse kinematics equations for the proposed screw wheeled omnidirectional mobile robot are derived and verified via simulation. The results show the effectiveness of both forward and inverse kinematics to deliver 3-DOF omnidirectional movements