考虑损伤时材料的断裂应力

工程结构的损伤分析、寿命预测及材料细观损伤机理与材料的强韧化研究，具有十分重要的工程意义，并具有广阔的发展前景。本文研究考虑损伤时材料的断裂应力，推导出了在表面能密度有限的情况下，损伤断裂应力的计算公式。     

F汽车方向机驱动轴的疲劳与断裂分析

F汽车进口后在索赔期内仅运行2800km,其方向机突然失灵,车与杨树相撞。在事故技术检查中发现方向机驱动轴破断。那么,该驱动轴是在车、树相撞中破断,还是在相撞前破断呢?本文对F汽车方向机驱动轴的破断进行了疲劳与断裂分析,其中有联接分析、受力分析、断口(宏观、微观和金相)分析,从而得出该件原为不合格件,断口为疲劳断口,是正常疲劳断裂的结论。致使索赔汽车谈判成功。     

S形内锁针张力带内固定治疗肩锁关节脱位

目的 :比较肩锁关节全脱位用S形内锁针张力带内固定法与传统克氏针固定法的效果。方法 :根据肩锁关节解剖学和生物力学特点 ,本文设计了S形内锁克氏针结合张力带内固定系统治疗肩锁关节全脱位 2 6例 (S形针组 ) ,并用传统克氏针张力带内固定 2 2例作为对照组 (传统组 )。结果 :S形针组优 2 2例 ,良 4例 ,差 0例。传统组优 13例 ,良 5例 ,差 4例 (P <0 .0 5 )。结论 :S形内锁针张力带内固定 ,为肩锁关节脱位的复位固定提供一种有效的方法     

Z-形钛合金钢板前路内固定术治疗胸腰椎爆裂性骨折的疗效观察

目的观察Z-形钛合金钢板前路内固度定术对胸腰椎爆裂性骨折患者的临床疗效。方法对60例胸腰段脊柱爆裂性骨折患者进行前方减压、椎体间植骨、Z-形钛钢板内固定,术后卧床3周,3周后戴支架起床活动。结果随访平均12.5个月,术后CT或MR显示椎管内压迫去除,植骨愈合。脊柱后凸Cobb角较术前改善12.7°,无继发脊柱后凸畸形。神经功能较术前有1~2级以上的改善。结论Z-形钛合金钢板前路内固定术对胸腰椎爆裂性骨折减压彻底,固定牢固,不破坏后稳定结构,并能一期重建脊柱系列。     

FRACTURES OF THE DISTAL PHALANX AND ASSOCIATED SOFT TISSUE AND OSSEOUS ABNORMALITIES IN 22 HORSES WITH OSSIFIED SCLEROTIC UNGUAL CARTILAGES DIAGNOSED WITH MAGNETIC RESONANCE IMAGING

Ungual cartilage ossification in the forelimb is a common finding in horses. Subtle abnormalities associated with the ungual cartilages can be difficult to identify on radiographs. Magnetic resonance (MR) imaging findings of 22 horses (23 forelimbs) with a fracture of the distal phalanx and ossified ungual cartilage were characterized and graded. All horses had a forelimb fracture. Eleven involved a left forelimb (seven medial; four lateral), and 12 involved a right forelimb (five medial; seven lateral). All fractures were nonarticular, simple in configuration, and nondisplaced. The fractures were oriented in an axial proximal to abaxial distal and palmar to dorsal direction, and extended from the base of the ossified ungual cartilage into the distal phalanx. The fracture involved the fossa of the collateral ligament on the distal phalanx in 17 of 23 limbs. The palmar process and ossified ungual cartilage was abnormally mineralized in all horses. Ligaments and soft tissues adjacent to the ossified ungual cartilages were affected in all horses. The routine site of fracture in this study at the base of the ossified ungual cartilage extending into the distal phalanx suggests a biomechanical cause or focal stress point from cycling. The ligamentous structures associated with the ungual cartilages were often affected, showed altered signal intensity as well as enlargement and were thought to be contributing to the lameness. In conclusion, ossified ungual cartilages may lead to fracture of the palmar process of the distal phalanx and injury of the ungual cartilage ligaments.     

THE USE OF COMPUTED TOMOGRAPHIC THREE‐DIMENSIONAL RECONSTRUCTIONS TO DEVELOP INSTRUCTIONAL MODELS FOR EQUINE PELVIC ULTRASONOGRAPHY

Ultrasonography has gained increased utility to diagnose pelvic fractures in horses; however, internal pelvic contours can be difficult to appreciate from external palpable landmarks. We developed three‐dimensional (3D) simulations of the pelvic ultrasonographic examination to assist with translation of pelvic contours into two‐dimensional (2D) images. Contiguous 1 mm transverse computed tomography (CT) images were acquired through an equine femur and hemipelvis using a single slice helical scanner. 3D surface models were created using a DICOM reader and imported into a 3D modeling and animation program. The bone models were combined with a purchased 3D horse model and the skin made translucent to visualize pelvic surface contours. 3D models of ultrasound transducers were made from reference photos, and a thin sector shape was created to depict the ultrasound beam. Ultrasonographic examinations were simulated by moving transducers on the skin surface and rectally to produce images of pelvic structures. Camera angles were manipulated to best illustrate the transducer–beam–bone interface. Fractures were created in multiple configurations. Animations were exported as QuickTime movie files for use in presentations coupled with corresponding ultrasound videoclips. 3D models provide a link between ultrasonographic technique and image generation by depicting the interaction of the transducer, ultrasound beam, and structure of interest. The horse model was important to facilitate understanding of the location of pelvic structures relative to the skin surface. While CT acquisition time was brief, manipulation within the 3D software program was time intensive. Results were worthwhile from an instructional standpoint based on user feedback.     

塑性土壤破碎方法的比较

用改装的三轴剪切仪对拉伸、扭转、弯曲、直剪、切割和纯切割等基本加载方式进行了详细研究。结果表明,弯曲加载是需要最小力及最少能耗使塑性土壤破碎的一种有效的加载方式。     

削片机主轴的断裂与研制

削片机是木材废料和林区剩余物综合利用的重要机械设备,给林区带来了显著的经济效益和社会效益。黑龙江省友好木材综合加工厂Ⅱ号削片机,使用43个月后其主轴完全破断。本文在实地调查分析的基础上,对主轴进行了受力分析和断裂失效分析,研制了新主轴。投产一年来,通过对主轴的径向跳动测试和刀盘端面跳动测试表明,新主轴较原主轴的结构合理,工作正常,给工厂带来了较大的经济效益。     

CONGENITAL DISLOCATION OF THE DEEP DIGITAL FLEXOR TENDON ASSOCIATED WITH HYPOPLASIA OF THE SUSTENTACULUM TALI IN A THOROUGHBRED COLT

An 11-month-old Thoroughbred colt was presented with a hard swelling at the proximal third of the right 4th metatarsal bone. A medial dislocation of the deep digital flexor tendon ( flexor digitorum profundus ) was also observed on the same leg. On the plantaroproximal-plantarodistal projection of the calcaneus, there was flattening and shortening of the sustentaculum tali. The smooth bony proliferation at the proximal third of the right 4th metatarus was compatible with a chronic splint bone fracture. This report describes a medial deep digital flexor dislocation associated with hypoplasia of the sustentaculum tali .     

A COMPARISON OF RADIOGRAPHY, COMPUTED TOMOGRAPHY, AND MAGNETIC RESONANCE IMAGING FOR THE DIAGNOSIS OF PALMAR PROCESS FRACTURES IN FOALS

The relative sensitivity of radiography, computed tomography, and magnetic resonance imaging for detecting palmar process fractures of the distal phalanx in foals was determined and the imaging findings were compared with histomorphologic evaluations of the palmar processes. Compared to radiography, computed tomography and magnetic resonance imaging did not improve the sensitivity for detection of palmar process fractures. Statistical agreement for palmar process fracture diagnosis was excellent among the three imaging modalities. Histomorphologic evaluations were more sensitive for diagnosis of palmar process fracture than any of the imaging modalities. Three-dimensional image reconstructions and volume measurements of distal phalanges and palmar process fracture fragments from computed tomography studies provided more complete anatomical information than radiography. Magnetic resonance imaging confirmed that the deep digital flexor tendon insertion on the distal phalanx is immediately axial to the site where palmar process fractures occur, and differentiated cartilage, bone, and soft tissue structures of the hoof.