International Journal of Experimental and Computational Biomechanics (10 papers in press)
Non-Newtonian Blood Flow and Coupled Blood-Wall Oxygen Mass Transport in a 180
by Mohammadamin Raoufi, Hamid Niazmand, Mahdi Pourramezan
Abstract: In contrast to straight blood vessels, more complicated flow patterns in tortuous vessels lead to a disruption of a regular distribution of oxygen on the vessel walls. This disturbance correspondingly plays a significant role in the origin and worsening of clogged arteries. In this study, oxygen mass transport in blood flow through a 180
Keywords: Hemodynamics; Mass transfer; Hemoglobin; Non-Newtonian fluid; Artery.
The effects of trabecular architectures on transferring dynamic loads to the brain.
by Siavash Hashemi, Ali Sadegh
Abstract: The SEM study revealed that the trabecular architectures in the subarachnoid space (SAS) are in the form of tree-shaped rods, pillars, plates or a complex network. In this paper the effects of pillar and tree-shaped trabeculae on transferring an impact load and a pressure wave to the brain have been investigated. Primarily, the validated global 3D FE model of the head and the neck was subjected to two cases of loading conditions; a Friedlander profile shock wave and a velocity (blunt) impact profile. Comparatively, both loadings had almost similar effect on the dura mater. The global model was employed and the pressure distributions on the dura mater (below the skull) for the blast and the blunt impact scenarios were extracted. On the other hand, two sets of local 3D FE models, including dura mater, gray matter and the SAS, were created. The first set of the local models consists of one model with no trabeculae in the SAS and two models with SAS having rod trabeculae with different diameter of their cross sections. The second set of local models consists of tree-shaped trabeculae, i.e., upright tree-shaped and inverted ones. Finally, the pressure histories, obtained from the global model for the blast and the blunt impact scenarios, were placed on the dura mater of the local models and the maximum principle strains in the brain for each case were calculated. The results indicated that the thickness, shape and architecture of the trabeculae would not affect the severity of loads transferring to the brain from shock waves. For the local models of set one, having rod trabeculae subjected to the blunt impact loading condition, not only the presence of trabeculae in the subarachnoid space, regardless of their constructions, would reduce the load transferring to the brain, but the thicker rod trabeculae created lower strain, hence provided more protection for the brain. Moreover, in cases of blunt impact scenario the upright tree shaped trabeculae perform stronger and more advantageous in protecting the brain when compared to the inverted ones.
Keywords: Brain Trabeculae; shockwave; blunt impact; load transfer; Finite Element.
FINITE ELEMENT ANALYSIS FOR KNEE IMPLANTS WITH SUITABLE MATERIAL COMBINATIONS
by Bhaskar Kumar Madeti, Chalamalasetti Srinivasa Rao
Abstract: Implants are compared with suitable material combinations. UHMWPE material is
used for interface component and TZP is used for Tibia plateau component (lower component)
and intercondylar groove (upper component) in knee joint. The finite element analysis is
performed for the Knee Implant for 600 N and for knee implant components for 600 N and
1000N body weights are considered. This study reveals the fact in case of any misalignment of components; the finite element analysis is performed for components individually in order to determine maximum possible von-Mises stresses. Grid convergence is performed in the present analysis.
Keywords: Knee implant; biomaterials; titanium alloys; UHMWPE; TZP,Stress Deformation.
HIGH RATE FAILURE PROPERTIES OF HUMAN AORTIC TISSUE UNDER LONGITUDINAL EXTENSION
by Piyush Gaur, Khyati Verma, Anoop Chawla, Sudipto Mukherjee, Sanjeev Lalwani, Rajesh Malhotra, Christian Mayer, Pronoy Ghosh, Ravi Kiran Chitteti
Abstract: Though traumatic rupture of the aorta (TRA) continues to be a major cause of fatality in motor vehicle crashes, its underlying mechanism at tissue level is still not well understood. A step towards gaining insight into the failure mechanism is to understand the failure properties of human aortic tissue at high strain rate loading. This study reports 18 uniaxial tensile tests performed on human aortic tissue in the longitudinal direction. Rectangular specimens were obtained from fresh human aortic tissue. Uniaxial quasi-static and dynamic tensile tests were performed at target strain rates of 0.001 s-1, 65 s-1, 130 s-1and 190 s-1 to failure. High-speed video tracking markers were used to measure the gripper to gripper displacement. Failure stress and strain were calculated at the location of failure in the gauge length of the specimen. The results of the study showed that the load-deformation relationship of aorta tissue is nonlinear and strain rate dependent with higher rate giving higher failure engineering stress and lower effective failure engineering strains. Across tests, the failure stress ranged from 0.86 MPa to 1.86 MPa and effective failure strain from 13.52% to 10.80 %. The data reported in this study can be used to develop strain rate dependent based constitutive models where high loading rates are of interest.
Keywords: Human soft tissues; Aorta; Impact; Strain rate dependence; Tissue failure; Tissue Tensile characterization.
HIGH STRAIN RATE COMPRESSIVE BEHAVIOUR OF HUMAN HEART
by Khyati Vema, Sudipto Mukherjee, Piyush Gaur, Anoop Chawla, Rajesh Malhotra, Sanjeev Lalwani
Abstract: Thoracic injuries incurred during automotive crashes constitute a significant portion of all fatal and nonfatal injuries. Understanding the underlying mechanisms of thoracic injuries is an important step in improving the crash safety of vehicles. Finite element human body models are becoming a valuable tool to analyse automotive related injuries to soft tissues. The human heart is one of the most important organs which can cause serious and fatal injuries in motor vehicle crashes (MVCs). In road crashes, the loading on the heart tissues is often at strain rates going up to strain rates of 100/s. A major step to gain insight into the mechanisms of heart injuries is to understand the compressive behavior of the human heart at these strain rates. This study reports a total of 20 compression tests performed on heart tissues at various strain rates ranging from 0.001/s to 200/s. High-speed videos recorded in the tests were analysed to calculate the displacement which was subsequently used to calculate green strain. Engineering stresses were calculated from the force measured and the initial cross-sectional area. The results of the study showed that the response of the human heart tissue in compression is non-linear and strain rate dependent, with the modulus variation with strain rate. The elastic modulus for all the tests at different strain rates ranged from 1.79e-3 MPa to 3.34 MPa in an effective compression strain of 15 % to 49%.
Keywords: Human Heart; Human soft tissues; Impact; Strain rate dependence; Compressive characterization.
Special Issue on: Recent Developments in Biomechanics and Biomechanics-focused Processes/Product Analysis/Development
EXPERIMENTAL STUDIES AND EFFECTIVE FINITE ELEMENT MODELLING OF FOOT DEFORMATION IN STANDING
by Shudong Li
Abstract: In this work, a full scale subject specific FE foot model is developed to simulate the deformation of human foot under a standing position similar to a Navicular Drop Test. The model used a full bone structure and effective embedded structure method to increase the modelling efficiency. Navicular drop tests have been performed and the displacement of the navicular bone is measured using 3D image analysing system. The experimental results show a good agreement with the numerical models and published data. The model is verified by comparing the numerical data for simple standing against subject specific navicular drop test. The detailed deformation of the navicular bone and factors affecting the navicular bone displacement and measurement are discussed.
Keywords: FE modelling; Navicular Drop Test.
EFFECTS OF ATHLETIC FOOTWEAR ON PLANTAR FORCE DURING ROPE SKIPPING
by Haibin Yu
Abstract: The purpose of this study was to investigate the plantar force and ground reaction forces of different rope skipping conditions with different sport shoes. Ten subjects were instructed to skip rope with one leg condition (OC) and two legs condition (TC).The conditions included the Novel Pedar-X system was used to collect plantar force information beneath the foot inside the sports shoes. Vertical ground reaction forces (VGRF) of each skip were measured on a force platform. The mean values of each group were calculated for comparison. It was found that the vertical ground reaction force TC (4.46 BW run- shoe and 4.27 BW jump-shoe) were greater than OC (3.18 BW run- shoe and 3.51 BW jump- shoe) (p<0.001). The results showed that OC with two shoes were significant higher than TC in all the variables of interest of Novel Pedar -X system. The force distribution patterns among two shoes were similar. During landing of rope skipping, plantar force occurred mainly at metatarsal head and hallux and lateral toes.
Keywords: Biomechanics; jumping rope; landing; plantar kinetics.
KINEMATIC ANALYSIS ON SLIDING SHOT PUT
by Peng Li
Abstract: In this paper, a comprehensive three-dimensional kinematic quantitative analysis has been applied to analyse the movement and biomechanics of throwing technology of a Chinese excellent women's shot. The filming is conducted with a multi-camera 3D imaging system during the championship. A Star high titanium 3-D signal TEC V1.0C three-dimensional video analysis software system is used for parsing with the RBI web parsing resolution. The human body model applied is Japan Matsui (16, 22 key parameters).The throwing operation is divided into five main stages: the Oscillating acceleration phase, the sliding stage, the transition phase and the Last Stage of Throwing. Research analysis for each phase has focused on different biomechanical characteristics and parameters. The key parameters for the throwing of the subject in this work critically compared to other data of related parameters of the domestic and foreign excellent athletes with reference to the general rule of shot put techniques. The key issues associated with the throwing and future biomechanical training is discussed.
Keywords: Biomechanics of throwing; Glide shot put technique; Speed shot.
ANALYSIS ON THE GAIT OF LOWER LIMBS IN DIFFERENT WALKING SPEED
by Xin Wang
Abstract: In order to find out the change of loading on lower limbs associated with different walking speeds, 15 young males and 15 females were tested in different walking speeds with barefoot. The kinematics and kinetic dates were collected by Codamotion capture system, ATMI force platform. Knee forces (KF) were calculated by Anybody software. The results shows that with increase of walking speed, the heel reaction force in sagittal and vertical axis increases, which results in weaker stability. The forces on the knee in three directions becomes significantly higher when walking at a faster speed, which results in an increase in the load and the risk of knee cartilage and ligament injury was increased too.
Keywords: gait; walking speed; lower limbs.
STUDY OF ISOKINETIC STRENGTH TRAINING'S REHABILITATING EFFECTS ON ELITE ATHLETES AFTER KNEE JOINT ALC RECONSTRUCTION SURGERY
by Zhanle Gao
Abstract: Anterior cruciate ligament (ACL) injury is one of the common knee injuries for most athletes and sports-active people. Arthroscopic reconstruction ACL is the preferred treatment. Rebuilding ACL for the rapid return to pre-injury level movement and function is an important goal for athletes. In this paper, the use of isokinetic strength training methods for athletes after ACL injury rehabilitation effect is reported. Thirty - one knee anterior cruciate ligament reconstruction athletes were divided into two groups, and were respectively subjected to 12 weeks traditional rehabilitation training and isokinetic strength training. It was found that constant strength training of the knee joint could improve the muscle strength of the athletes more quickly which provides better rehabilitation training for the postoperative recovery of athletes to return to the track.
Keywords: isokinetic exercise; anterior cruciate ligament reconstruction; rehabilitation.