The Research Of Fretting Behavior Of Medical Magnesium Alloy Bone Plate

Plate internal fixation is one of the most effective method of the treatment of bone trauma, it has been widely used in clinical practice, and to reduce the pain for patients. Bone plate and bone screw is the key component of internal fixation. Magnesium alloy bone plate can not only corrosion and degradation, and the proportion and the bones very similar, a sense of weight-bearing light, free magnesium ion is conducive to bone healing, harmless to the human body, stress shielding effect, no secondary surgery, has good biocompatibility, mechanical compatibility and so on. These characteristics make magnesium alloy become the best choice for the traditional bone plate substitute. So researched of micro motion behavior of medical magnesium alloy bone plate using the existing problems of bone plate in the clinical application and Characteristics of magnesium alloys.There are a lot of friction pairs in the bone plate system, which can not be ignored in the effect of the blood supply and the destruction of the surface layer of the bone plate. The analysis results of the ball/plate contact pair in the bone plate system with ABAQUS software are very close to the Hertz theory. Therefore, it is reasonable to analyze the behavior of micro motion by finite element simulation technology; In addition, the stress change of the contact surface of the ball plate provides a basis for the analysis of the mechanism of the magnesium alloy material.Forceing to stop the body of the lesion is in order to prevent the occurrence of the bone plate with excessive force lead to deformation or fracture and other accidents,after the bone plate is implanted in the human body. Moderate rehabilitation training is in order to prevent the occurrence of joint adhesion, bone necrosis or osteoporosis and other phenomena. Through the modal analysis, it is found that the ability of the bone plate to resist external disturbance and the vibration characteristic parameters can be improved effectively by increasing the preload and increasing the number of the bone nail; In the case of vibration and other external interference, the position of far away from the pre tightening bone screw hole, easy to occur fretting friction. In the bone plate design, attention should be paid to improve the optimization.Magnesium alloy has many advantages compared with titanium alloy and stainless steel, but the mechanical properties of magnesium alloy are relatively poor. In this paper, the fatigue life, safety factor, maximum stress and fatigue cumulative damage parameters of magnesium alloy bone plate in large plane bending, lateral bending and torsion deformation are explored by fretting fatigue analysis. Through the analysis and comparison of the experience and the maximum stress value, it is a determine to the most prone to large plane bending easily.The surface texture of a variety of density is designed on the inner surface of the bone plate is In order to facilitate the storage of drugs, improve the stress state, and improve the fatigue life of the bone plate. Through the analysis of the micro motion of the texture bone plate, it is found that the sparse texture bone plate is the best one.The hardness of magnesium alloy material than the titanium alloy and stainless steel, in the early stage of the magnesium alloy protection, it also need micro-arc oxidation. In micro situation, to explore the extent of damage and damage mechanism of the bone plate surface. In this paper, we design the experiment of tangential fretting friction and take into account the load factor. In order to increase the contrast, the large dynamic test with the surface texture is also designed. The morphology of wear scar was observed by microscope and scanning electron microscope, the data were analyzed by Origin software. Through the analysis and comparison, it is found that the dynamic degree, the load and the operation mode are the law of damage. It is also known that the design of the surface texture is beneficial to reduce the friction coefficient, on the basis of optimizing the structure of the surface texture and density.According to the characterization of wear scar and the fretting wear mechanism of other materials, the mechanism of WE43 tangential fretting wear was established. Finite element simulation technology, is explained from the Angle of the stress distribution change damage mechanism, and illustrates the design of surface texture to improve the mechanism of surface friction. Based on the experimental data, the F-D characteristic curve of a single cycle was constructed, and the relationship between the friction force, the dynamic degree and the frequency were analyzed, and the mathematical model of the three-dimensional characteristic of F-D-N micro motion cycle was established.