| 1. |
- Jiang, X., et al.
(författare)
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An investigation of biomechanical mechanisms of occupant femur injuries under compression-bending load
- 2014
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Ingår i: Lixue Xuebao/Chinese Journal of Theoretical and Applied Mechanics. - 0459-1879. ; 46:3, s. 465-474
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Tidskriftsartikel (refereegranskat)abstract
- Occupant femur fractures occur frequently under compression-bending load in the frontal crashes of passenger cars. In order to explore the injury mechanisms and tolerances of occupants' femur in this load condition, a finite element model of the lower extremity in the sitting posture was developed based on the anatomy of a 50th percentile male. Then the model was validated against two types of cadaver tests, including three-point dynamic bending test of the femur and the axial impact test on the knee-thigh complex. A study of femur fractures under compression-bending load has been carried out using an analytical model of the curved beam. Furthermore, six virtual tests were conducted using the validated finite element model. The results show that the location of bone fractures and the tolerance of the femur depend on both bending load and axial compression. With the increasing preload of the bending moment from 0 to 676 Nm, the femur fracture location was shift from the femoral neck to the shaft. Regarding the tests with fractures occurring in the femoral neck, the tolerance of the femur is between 285 and 296 Nm. For the other tests with fractures located in the femoral shaft, the tolerance of the femur is between 381 and 443 Nm. The results indicated that the femur fractures always occurred at the femoral neck in axial impact tests on the knee-thigh complex, but in real world car frontal impacts the femoral shaft fractures can be observed frequently.
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| 2. |
- Wang, F., et al.
(författare)
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Finite element analysis of human rib fracture under various impact loading conditions
- 2014
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Ingår i: Lixue Xuebao/Chinese Journal of Theoretical and Applied Mechanics. - 0459-1879. ; 46:2, s. 300-307
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed at investigating the mechanism of the human rib fracture under various impact loading conditions based on different failure models. For this purpose, a validated FE thorax model was utilized for analysis of the rib fractures. Based on the human anatomical structures, the human thorax FE model consists of ribs, vertebras, sternum, costal cartilages, internal organs, and soft tissues. Material properties used in this model were based on the published literature. The phenomenon of human rib fractures was simulated in different configurations, including structural experiments of single rib and human thorax frontal crash experiments with a cylinder impactor. Based on different rib fracture failure models in human injury biomechanics, the rib fractures from simulations were analyzed and compared with the impact responses obtained from all of the experiments from the literature. The simulation results with the FE model showed that the applicability of rib fracture failure model would depend on the loading conditions. It was proved that the FE model could be used in research of human rib fracture biomechanics under various impact loading conditions in vehicle traffic accidents.
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| 3. |
- Wang, F., et al.
(författare)
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Numerical analysis of human thoracic injury responses in vehicle lateral and oblique crashes
- 2016
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Ingår i: Lixue Xuebao/Chinese Journal of Theoretical and Applied Mechanics. - 0459-1879. ; 48:1, s. 225-234
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Tidskriftsartikel (refereegranskat)abstract
- Vehicle lateral and oblique impacts account for a large proportion of traffic accidents resulting in serious occupant injuries. There is a lack of adequate investigations into the thoracic injury biomechanics in lateral and oblique impacts, compared to thoracic injuries in frontal impacts. Therefore, this article aims to study the biomechanical response and injury related parameters of the thorax under these two impact scenarios. First, an FE model of entire human body in sitting posture is established via combining previously developed FE models of the thorax, the head-neck and the lower extremities. Afterwards, the sitting human body FE model is used to simulate the 7 cadaver experiments by Shaw et al. in lateral and oblique impact to thorax. The calculated injury related response curves of the impact force, thorax deformation, and force-deformation are correspondingly within the biomechanical response curve corridors from experiments, which verified the validity of the sitting human body model. The peak value of impact force is close to the upper boundary of the test corridor, and the deformation approaches the lower boundary of the experimental results. Meanwhile, the peak of impact force from the lateral impact simulations is slightly larger than the resulting peak from oblique impact, and the peak of the timing is earlier. The peak of chest deformation in lateral impacts is smaller than that from the oblique impact, and the peak also appears earlier. This presents a trend consistent with the experimental results. Analysis shows that under the same intensity of impact load the thorax tolerance in lateral impact is higher than that in oblique impact. The thorax finite element model can accurately reproduce biomechanical response process in the lateral and oblique experiments. The model demonstrates good biofidelity to study the occupant thorax injury biomechanics.
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| 4. |
- Xiao, Sen, et al.
(författare)
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Analysis of chest injury in frontal impact via finite element modelling based on biomechanical experiment
- 2017
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Ingår i: Lixue Xuebao/Chinese Journal of Theoretical and Applied Mechanics. - 0459-1879. ; 49:1, s. 191-201
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Tidskriftsartikel (refereegranskat)abstract
- The usage of the seatbelt as a part of the vehicle protection system has immensely promoted occupant safety. However, recent accident investigation shows that it is necessary to increase the chest injury protective e_ciency in frontal impact condition. This study aims to investigate the influence of seatbelt system design variables on occupant chest injury related physical parameters at varying impact conditions, especially concerning with the chest deflection and distribution of rib stress/strain. The study is conducted by using human body FE model in combination with post mortem human subjects tests. An FE model of the belted occupant is therefore established by using a baseline human body FE model (GHBMC), which is validated according to detailed experimental data regarding kinematics, seatbelt force and chest deflection. A parameter study is implemented in terms of seatbelt position, seatbelt angle and impact speed to determine the influence of seatbelt utilization on occupant thoracic injury in frontal impact. The results show that the influence of seatbelt position on chest deflection and distribution of rib stress/strain is greater than that of the seatbelt angle. Meanwhile, the trends of chest deflections are the same with the trends of the rib stress/strain responses while the changes of seatbelt design variables. This study provides a virtual test method on investigation of the chest injury biomechanics related to the seatbelt design variables. Furthermore, the results from this study of chest injury mechanism will also provide a reference for optimizing of the occupant restraint system. © 2017, Editorial Office of Chinese Journal of Theoretical and Applied Mechanics. All right reserved.
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| 5. |
- Li, L, et al.
(författare)
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Damage coupled thermo-mechanical model for rock failure process and applications
- 2006
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Ingår i: CHINESE JOURNAL OF THEORETICAL AND APPLIED MECHANICS. - 0459-1879. ; 38:4, s. 505-513
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Tidskriftsartikel (refereegranskat)abstract
- Based on the heterogeneous characteristics of rock at mesoscopic level, the thermo-mechanical (TM) coupled behavior during the failure process of rock subjected to thermal stress is analyzed with elastic damage mechanics and thermo-elastic theory. A mesoscopic TM coupling model, implemented in rock fracture process analysis (RFPA), is proposed, which can be used to study the damage and failure process, as well as elastic stress for the coupled TM rock problem. With the numerical model, the damage and associated mechanical properties evolution of mesoscopic structure in rocks subjected to TM loading can be analyzed. Numerical simulation is carried out to investigate the stability of the rock pillar in a hard rock laboratory. The numerically obtained stress field, failure pattern of pillar rock and associated acoustic emission (AE) events all agree well with the in-situ data, which shows that the proposed model is reasonable and effective, and may provide guides for the experiment design and associated applications
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| 6. |
- Lundström, Niklas L.P., et al.
(författare)
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Dynamics in large generators due to oval rotorand triangular stator shape
- 2011
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Ingår i: Acta Mechanica Sinica. - Beijing : Science Press. - 0567-7718 .- 0459-1879 .- 1614-3116. ; 27:1, s. 18-27
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Tidskriftsartikel (refereegranskat)abstract
- Earlier measurements in large synchronous generatorsindicate the existence of complex whirling motion,and also deviations of shape in both the rotor and the stator.These non-symmetric geometries produce an attraction forcebetween the rotor and the stator, called unbalanced magneticpull (UMP). The target of this paper is to analyse responsesdue to certain deviations of shape in the rotor and the stator.In particular, the perturbation on the rotor is consideredto be of oval character, and the perturbations of the statorare considered triangular. By numerical and analytical methodsit is concluded for which generator parameters harmfulconditions, such as complicated whirling motion and highamplitudes, will occur. During maintenance of hydro powergenerators the shapes of the rotor and stator are frequentlymeasured. The results from this paper can be used to evaluatesuch measurements and to explain the existence of complexwhirling motion.
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| 7. |
- Tzuchiang, W, et al.
(författare)
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A crack perpendicular to and terminating at a bimaterial interface
- 1998
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Ingår i: Acta Mechanica Sinica. - 0567-7718 .- 0459-1879. ; 14:1, s. 35-36
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Tidskriftsartikel (refereegranskat)abstract
- Using dislocation simulation approach, the basic equation for a finite crack perpendicular to and terminating at a bimaterial interface is formulated. A novel expansion method is proposed for solving the problem. The complete solution to the problem, including the explicit formulae for the T stresses ahead of the crack tip and the stress intensity factors are presented. The stress field characteristics are analysed in detail. It is found that normal stresses
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| 8. |
- Xu, Yan, et al.
(författare)
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Reduced-order modeling of train-curved-slab-track dynamics with the effects of fastening failures
- 2022
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Ingår i: Acta Mechanica Sinica. - : Springer Nature. - 0567-7718 .- 0459-1879 .- 1614-3116. ; 38
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Tidskriftsartikel (refereegranskat)abstract
- Fastening failures have frequently been found on China high-speed railway curved tracks in recent years. Thus the influence of fastening failures on high-speed train-track interaction in curved track needs to be analyzed. A train-curved slab track interaction model is built, in which the real shape of the curved rail is considered and modeled with reduced beam model (RBM) and curved beam theory, and the slabs are modeled with four-nodes Kirchhoff-Love plate elements. The present model is validated at first with different traditional models. Then the influence of fastening failure in curved slab track on train-track interaction dynamics is studied. A different number of failed fastenings is assumed to occur at the curved track, and different types of fastening failure including the fatigue fracture of the clip structure and failure of the rail pad are considered. Based on the calculation results, the fatigue fracture of the clip structure has little influence on train-track interaction dynamics. But when rail pad failure happens and its equivalent vertical stiffness and damping are less than one-tenth of its original, the fastening failure seriously affects the high-speed train operation safety, and it must be prevented
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