基于CT数据颅骨有限元模型的建立及枕部坠落伤和打击伤应力分析的研究

发布时间：2018-04-12 15:41

本文选题：颅骨 + 有限元分析　；参考：《河北医科大学》2017年硕士论文

【摘要】：目的:颅脑是人体最重要的生命中枢,也是损伤后致死率和致残率最高的器官。在法医伤害案件中,头部常是主要打击的目标,因此对颅骨坠落伤和打击伤的鉴别,也一直是法医检案鉴定研究的重点和难点。本研究基于正常人体头部CT数据对颅骨进行三维重建并生成颅骨有限元模型。用该经过有效性验证后的有限元模型进行枕部坠落伤和打击伤模拟和力学分析。以数字技术为颅骨损伤中坠落伤和打击伤的鉴别提供理论参考。方法:1选取一名成年健康女性作为模拟对象,利用螺旋CT采集颅骨数据。2利用Mimics 15.0软件和Geomagic Studio 12.0软件建立颅骨三维几何模型3在Mimics 15.0的3-matic 7.0中和ANSYS Workbench 14.0的Explict Dynamics(LS-DYNA Export)模块构建颅骨有限元模型。4与Yoganandan尸体实验进行对比来验证模型有效性。5在ANSYS Workbench 14.0和LS-DYNA 971软件中模拟5.1 m/s、6m/s、10 m/s的速度下枕部坠落伤和打击伤。分析这两种工况应力传播途径,比较应力分布情况、接触力-时间曲线、冲击与对冲部位压力变化。结果:1成功地建立了除下颌骨、舌骨以外的颅骨三维几何模型。2在Mimics 15.0的3-matic模块中和ANSYS Workbench 14.0中生成了颅骨有限元模型。其中包括枕骨密质1个、枕骨松质2个、其余颅骨密质1个和其余颅骨松质10个,总节点数为238009个,总单元数为942663个。3依据Yoganandan的尸体实验对本研究所建立的颅骨有限元模型进行验证。尸体实验峰值接触力为14034N,本验证实验峰值接触力为13323N,比文献实验小了约5%。当接触力达到峰值后,曲线有下降趋势表明颅骨发生了塑性屈服。本研究得出的接触力-位移曲线与参考的验证实验测得的曲线在趋势上基本保持了相似性,证明了本实验构建的有限元模型的有效性,可以进一步进行颅骨损伤的生物力学分析研究。4联合ANSYS Workbench 14.0和LS-DYNA 971软件,模拟了在不同速度下颅骨枕部的坠落伤,同时输出了等效应力(Von Mises Stress)分布云图。由应力云图可知,枕部坠落伤时应力主要传播途径为枕部-颅底-额部;以5.1 m/s速度碰撞时,应力除主要集中于枕骨中部外,还在枕骨周围骨缝、枕内隆凸、枕骨大孔、枕骨基底部、颈静脉孔、乙状窦沟、内耳门、颞骨岩部尖端、破裂孔、卵圆孔、垂体窝、额骨眶板、翼点附近、颧弓、眶下裂及上颌骨处形成应力集中区;以6 m/s速度碰撞时,应力除分布于上述部位以外,还波及到视神经管和蝶骨小翼;以10m/s速度碰撞时,应力集中部位又增加了筛板以及额骨眉间部位。同时比较枕部在不同碰撞速度下接触力-时间曲线可得知:随着坠落高度升高,碰撞速度越大,接触面的峰值接触力越大,达到峰值接触力的时间越早。额部和枕部压力曲线表明:冲击处的枕部压力为正值,而对冲处的压力为正负值交替变化。5联合ANSYS Workbench 14.0和LS-DYNA 971软件,模拟了在不同速度下颅骨枕部的锤子打击伤,输出了等效应力(Von Mises Stress)分布云图。由应力云图可知,打击头颅枕骨中部时,应力也是主要沿着枕部-颅底-额部途径进行传播;以5.1 m/s速度打击时,应力集中部位出现在枕骨中部,枕骨周围骨缝、枕内隆凸、枕骨大孔、枕骨基底部、颈静脉孔、乙状窦沟、内耳门、颞骨岩部尖端、破裂孔、卵圆孔、垂体窝、额骨眶板、翼点附近、颧弓、眶下裂及上颌骨处;以6 m/s速度打击时,应力集中部位除上述部位以外,还波及到视神经管;以10 m/s速度碰撞时,应力集中部位也增加了筛板以及额骨眉间部位。但应力集中范围比同速度坠落的小。比较打击部位在不同速度下接触力-时间曲线,表明打击速度越大,则接触面的峰值接触力越大,达到峰值接触力的时间越早。额部和枕部压力曲线表明:冲击处的枕部压力为正值,而对冲处的额部压力为正负值交替变化。6同速度下,两种不同损伤的应力云图比较显示:坠落伤应力集中区域比打击伤更广;接触力-时间曲线比较显示:坠落伤峰值接触力比打击伤大;冲击处的枕部压力比较显示:坠落伤和打击伤所造成的枕部压力差别不大;对冲处的额部压力比较显示:坠落伤时额部正负压变化幅度比打击伤更大。结论:1基于正常人头颅CT数据,应用相应软件重建出解剖结构相似度高的人体颅骨三维几何模型和有限元模型。2与国外经典的尸体头部损伤实验进行比较,验证了本研究模型的有效性,可进行生物力学仿真模拟。3成功模拟了颅骨枕部的坠落伤和暴力打击伤并比较了两种损伤生物力学指标。可知枕骨中部受力时应力传播主要方向为枕部-颅底-额部。颅骨应力集中区域与临床上颅底骨折的好发部位一致。同工况下,速度越大,越易发生颅骨损伤。对冲性额部骨折的原因可能是由于正负压交替所致的疲劳性骨折。4同速度下,坠落造成的减速性颅骨损伤比无垫衬暴力打击造成的颅骨加速性损伤应力分布范围更广、后果更严重、更易发生对冲性骨折。
[Abstract]:Objective: the brain is the most important life center of human body after injury, and mortality rate and disability rate highest organ. In forensic injury cases, the head is often the main target of attack, so the skull fall injury and injury against discrimination, also has been the focus and difficulty of forensic inspection case identification. This study is based on the normal human head CT data reconstruction of skull and skull formation. The finite element model through finite element validation model after analysis and Simulation of mechanical injury against injury and fall to digital technology. The occipital skull injury in fall injury and identification of combat injuries and provide a theoretical reference. Methods: 1 selected a healthy adult female as the simulation object, using spiral CT acquisition skull data.2 using Mimics 15 and Geomagic Studio 12 software to establish the three-dimensional geometric model of the skull in 3 Mimics 15 3-matic 7 Workbench 14 and ANSYS Explict Dynamics (LS-DYNA Export) module to build the finite element model of.4 and Yoganandan of skull cadaver experiment validated the effectiveness of the.5 model in ANSYS Workbench 14 and LS-DYNA 971 software in the simulation of 5.1 m/s, 6m/s 10, m/s speed occipitalia falling injury and combat injuries. Analysis of these two conditions should be comparison of force transmission, stress distribution, contact force time curve, change of pressure impact and hedge positions. Results: 1 successfully established in the mandible,.2 three-dimensional geometric model of the skull hyoid outside in the Mimics 15 3-matic module and ANSYS Workbench 14 are generated in the skull. The finite element model including the occipital cortical 1, the remaining 2 cancellous and cortical skull 1 and the rest of the skull cancellous 10, the total number of nodes was 238009, the total number of units for 942663.3 according to Yoganandan's body experiment in this study The skull established finite element model is verified. The body experiment peak contact force is 14034N, the experiment of peak contact force is 13323N, than the experimental small when the contact force is about 5%. after the peak, the curve downward trend shows that the skull occurred plastic yield. Experimental verification of the contact force - displacement curve with reference to the measured curve in the trend to maintain the basic similarity, proves the validity of the finite element model of the constructed, can further biomechanical analysis of skull injury.4 combined with ANSYS Workbench 14 and LS-DYNA 971 software to simulate the skull at different speeds occipital falls, while the output. The equivalent stress (Von Mises Stress) distribution. By the stress nephogram of the falling occipital stress mainly transmitted occipital skull base - forehead; at a speed of 5.1 m/s collision, in addition to the main stress To focus on the central, still occipital sutures, internal occipital protuberance, foramen magnum, basilar part of occipital bone, jugular foramen, sigmoid sinus, internal auditory meatus, petrous bone, fracture hole, foramen ovale, pituitary fossa, orbital plate frontal, pterional near the zygomatic arch, inferior orbital fissure jaw and the formation of stress concentration area; at a speed of 6 m/s collision, in addition to stress distributed in the area outside, but also affects the optic canal and the sphenoids; at the speed of 10m/s collision, stress concentration increased and the frontal glabellar area. At the same time plate is occipital in different collision speeds contact force time curve can be found: the falling height increased with impact velocity increasing, the contact surface of the peak contact force increases, reaches the peak contact force earlier. Frontal and occipital pressure curve showed that the occipital pressure shock is positive, and the hedge at a pressure of alternating positive and negative value of.5 Combined with ANSYS Workbench 14 and LS-DYNA 971 software to simulate the skull at different speeds occipitalia hammer against injury, the output of the equivalent stress (Von Mises Stress) distribution. By the stress nephogram of the blow head occipital central, stress is mainly along the occipital skull bottom - - forehead way of communication at a speed of 5.1 m/s; blow when the stress concentration appears in the central part of the occipital, occipital sutures, internal occipital protuberance, foramen magnum, basilar part of occipital bone, jugular foramen, sigmoid sinus, internal auditory meatus, petrous bone, fracture hole, foramen ovale, pituitary fossa, orbital frontal plate. Pterional near the zygomatic arch, orbital fissure and maxilla; at a speed of 6 m/s blow when the stress concentration position in addition to the site, but also affects the optic canal; at a speed of 10 m/s when the collision stress concentration also increased and the frontal region between the eyebrows plate. But the stress concentration range than the same speed Fall. Small striking position of contact force under different velocity - time curve, hit that greater speed, contact the peak contact force increases, reaches the peak contact force earlier. Frontal and occipital pressure curve showed that the occipital pressure shock is positive, and the pressure on the forehead the positive and negative value for punching alternating with.6 speed under two different damage stress nephogram comparison shows: falling injury stress concentration area than against injury is wider; contact force time curve shows: falling injury peak contact force than combat injuries; occipital pressure shock comparison shows: pillow the pressure difference caused by falling injury and trauma; frontal pressure at the hedge comparison shows that when the amount of positive and negative pressure fall injury changes more sharply than combat injuries. Conclusion: 1 normal human brain CT data based on the application of the corresponding software to reconstruct anatomical structure similarity Comparison of human skull injury experimental three-dimensional geometric model and finite element model of.2 and foreign classic body head high, the validation of the research model, for biomechanical simulation.3 successfully simulated the occipital skull fall injury and violence against injury and compared two indicators. The biomechanics of the middle occipital when the stress propagation in the main direction for the occipital skull base - frontal skull. Stress concentration area and the clinical skull base fracture predilection site. Under the same operating condition, greater speed, more prone to injury. The causes of fracture of skull frontal may be due to fatigue fracture caused by alternating positive and negative pressure with the speed of.4, caused by the fall of the skull injury than deceleration pad violence strikes skull accelerated injury stress distribution in a wider range, more serious consequences, more prone to hedge fractures.

【学位授予单位】：河北医科大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R651.15

【参考文献】