Abstract:The parellel light measurement and analysis system was designed and manufactured for research on kinematics of the whole lumbar spine.A loading frame was improved to decrease interference of experiment equipment for movement of lumbar spine.Along with load was changed,fresh human ligamentous specimens of lumbar spine were presented the different motion;The movement of three marks,which fixed in vertebrae,were separately projected to light screen of the system,kinematically recorded with video camera,inputted to image processing system.Then,according to prineiple of rigidity movement we proceeded with calculation,and obtained three-dimensional motion measurement of marks and kinematic characteristic of the whole lumbar spine.
1994, 9(4):196-201. DOI: 10.3871/j.1004-7220.1994.4.201.
Abstract:This paper reports first our comparative study on the qualitative performance of varied prosthetic valves in current use It showed that the bileaflet mechanical valve is the optimum valve prostheses,but with disadvantages of a narrow central channel and big peak backflow.The author based on the above results designed a model of downstream direction bileaflet mechanical valve and used finite bulk method to calculate the velocity and shear stress profiles of this valve.The results showed that both the velocity and shear stress profiles obtained were of much better quality.
1994, 9(4):202-206. DOI: 10.3871/j.1004-7220.1994.4.206.
Abstract:In this study,each mandibular tooth was loaded vertically,the strains of apical alveolar bone surfaces of the loaded tooth and the adjacent teeth were measured.The data were interpreted in order to find the occlusal force transmission pattern by polynomial regression fit method.The result indicates that under loading condition the occlusal force is transmitted to alveolar bone by peridental membrane and dispersed in the adjacent area.The force transmission and dispersion of the bilaterally same teeth on both sides follow the same rule and cloud were be described by 3 powers polynomial regression curve.The nearer the loaded tooth,the higher the strains of the alveolar bone and vice versa The force gradually tapers off to zero in the position of the third adjacent tooth.
1994, 9(4):212-216. DOI: 10.3871/j.1004-7220.1994.4.216.
Abstract:The objective of this study was to perform theoretical analysis involving the head-neck of 4 cases human head with sufficient precision and reliability so that a validation of the analytical model can be made for the impact situation,and to determine the skull-brain injury tolerance in the human head analysis from the engineering data obtained from the theoretical results.When the skull-brain is impacted directly,the brain also deforms and skull internal pressures increase at the site of local skull deformation.Research is currently being conducted by AISA to develop a comprehensive finite element method(FEM)representation of the entire head and neck capable of simulating the role of skull deformation,skull stresses,gross head motions,and stresses waves in the skull and brain.These parmaeters include translational and rotational acceleration,rotational velocities and contact forces,and procedures are now available to assess the complete dynamics response of the head in test dummies subjected to impact.Here,the main emphasis is an analysis of three dimensional FEM for skull-brain response to pact drawn on automatic formulated picture.
1994, 9(4):217-221. DOI: 10.3871/j.1004-7220.1994.4.221.
Abstract:It is important to reveal the biomechanical responses of connective tissue to the physical activity,especially for the intensive exercise.The purpose of this work is to investigate the histologic,radiographical and biomechanical responses of connective tissues to intensive physical activity.Rabbits put in an electric cage with high voltage,which made the animals jump and run for 360 times daily.Along with exercise,the X-ray pictures of rabbit tibiae were taken weekly,and the histologic changes of tibiae,insertions of Achilles tendon were examined.The mechanical properties of tibiae under three bending test and biomechanical properties of Achilles tendon,flexor digitorum profundus and medial collateral ligament of the knee under axial loading were determined at 4,21,42 days of exercise.The observations of radiography revealed that a lot of periosteitis of tibia e occured in the early stage of exercise,and these periosteal reactions developed into the new bone tissues at 21,42 days of exercise,so the sectional area of tibiae increased and the tibiae can bear a more heavy burden.The results of biomechanical testS of soft tissues showed that the failure loads,linear loads and energy absorptions increased followed 4,21,42 days of execrcise.These observations indicated that the connective tissues can adapt to the intensive exercise according to Wollflaw.The increase of mechanical properties of connective tissues are benificial for the athletes to prevent sports injuries in physical trainings and competitions.
1994, 9(4):222-226. DOI: 10.3871/j.1004-7220.1994.4.226.
Abstract:The biomechanics of the conjoined tendon(the short head of the biceps and the coracobrachialis muscle) to anterior stability was investigated in 8 cadaver shoulders.Translation tests at 90°abduction and 90°external rotation of the arm were performed by a 1.5 Kg anterior force.The position of the humeral head was monitored by a trimensional tracking device with the conjoined tendon at the original position of transfered under the subscapularis muscle;with 0 Kg,1.5 Kg Or 3 Kg loads applied on the conjoined tendon;and with the capsule intact or damaged by a Bankart lesion.the anterior displacement of the humeral head under 1.5 Kg force was significantly decreased with increasing conjoined tendon loading,especially when the conjoined tendon transfered in the capsular-damaged shoulder.