The Establishment Of A Three-dimension Finite Element Model Of Shoulder And Mechanical Analysis In Lateral Impact

In road accidents,vehicle lateral collisions accounted for about 1/3,and the improvement of vehicle front collision safety standards made lateral collisions one of the most important fatal causes in accidents.In the lateral impact,the shoulder was directly subjected to impact and charged with the main load,reducing the load applied to the thorax in some extent.On the one hand,the study of the shoulder impact helps to improve the protection of upper limbs.On the other hand,the protection function of the shoulder and upper limbs on the chest can be analyzed.At present,there are few reports on the establishment of the three-dimensional finite element model of the shoulder and its collision mechanics analysis in domestic.The purpose of this paper is to establish a three-dimensional finite element model of the shoulder and perform mechanical analysis.The main tasks are as follows:(1)The progress of shoulder modelling and injury research were reviewed.The biomechanical research methods were briefly summarized.The anatomy of the shoulder,common injuries and treatment were introduced.(2)Based on the principle of reverse engineering,the human shoulder geometry and finite element model(including bones,ligaments,cartilage,muscle,etc.)were constructed using commercial softwares.The image of the three-dimensional solid model is clear,the outer surface is smooth,and the spatial position is relatively accurate.The establishment of the model reflected the complex geometric shape of the shoulder and the unevenness of the bone density.The model can be used as a platform for shoulder biomechanical analysis or a universal tool for further research on the biomechanics of the shoulder.(3)Static tensile and dynamic impact verification were performed on the shoulder model.Lateral loading was used to obtain the displacements of key points.The displacements of key points were compared with the experimental data in the literature.The rigid mass lateral impact on the model at 1.5m/s was simulated and the changes of contact force were analyzed.The simulations were in agreement with experimental results,the model was validated finally.(4)The mechanical analysis of the shoulder lateral impact was performed at the speed of 3.5m/s and 6m/s,respectively.Von Mises stress distribution of the main bones obtained under the two working conditions were analyzed and compared.High-risk fracture positions were predicted.The main conclusions were as follows: Under different collision speed,repetitive and non-uniform changes occured in the stress of various bony tissues.With the increase of speed,the peak stress increased accordingly,and the peak stress growth rate was higher than the speed growth rate.Peak stress occurred in the neck of the scapula,the surgical neck of the humerus,and the inferior surface of the clavicle during the collision,and the magnitude of the stress peak decreased in this order.It was speculated that fractures were most likely to occur in the scapular neck,the surgical neck of the humerus,and the subclavicular surface in the collision.The scapular mainly beared the load.The scapular neck,scapular ridge and lateral border of the scapula played the role of stress transmission and dispersion.Both the upper and lower surface of the clavicle were prone to stress concentration,and the stress concentration on the lower surface was more obvious.When the fracture was fixed,the upper and lower surfaces should be supported.