基于有限元分析方法的连杆螺栓改进设计

根据生产企业的实际情况,提出了在应力集中严重的连杆螺栓头部与杆部过渡圆弧处进行局部滚压的改进措施,并通过有限元分析手段,得出当滚压力达到20kN时,就能使连杆螺栓在不改变原结构的前提下满足疲劳寿命的要求。     

趋势面分析在滑坡防治工程设计中的应用

滑坡治理工程的设计主要依据滑坡面及滑体方量,滑坡的上表面一般很容易得到,而下表面则可以根据地形图中等高线来确定,但是要得到准确的滑坡面则相对较难,常用的方法是选择适当的个别点进行钻探,测得该点处滑坡厚度,再由此模拟滑坡面。以四川省古蔺县蔺双公路K1＋100滑坡的滑动面（带）为例,采用多元统计的趋势面分析方法将滑坡面模拟成空间的一个曲面,求出曲面后则可计算滑坡推力、设计相应的加固方法,还可以通过滑动曲面计算滑坡的总方量。     

膨胀性岩质边坡加固方案的数值试验研究

膨胀性岩质边坡,由于其复杂性,加固方案不易确定。运用有限元方法对膨胀性岩体边坡的加固措施进行了较全面的数值试验研究,得出了坡顶超载与竖向位移、节理间距与坡顶变形及锚杆对坡顶变形影响的规律。该成果可为膨胀性岩质边坡加固方案的确定提供科学依据。     

海岸立式油罐设计问题的探讨

位于台风区海岸立式油罐的设计应考虑如下问题：风速的取值应以该地区台风风速作为瞬时风速计算瞬时风压值，若以３０ａ 一遇时距为１０ｍｉｎ的基本风压计算除乘以转换系数Ｋ２外，宜加大２０％－４０％；罐底是否设置地脚螺栓应按风压引起的倾覆力矩校该其稳定稳定性，当倾覆力矩大于固定载荷抵抗力矩的三分之二时才考虎设置地脚螺栓；油罐盘梯方位应放在背风方位，盘梯结构应带有三角架及内外侧板结构，罐体的防腐应以防止海水中     

桂梧高速公路高边坡加固中的框架锚索技术

针对公路工程高边坡治理技术中的锚索框架加固方法,通过相应设计和施工工艺在实践中的运用,达到经济上合理,技术上可行的验证。从工程实践中说明了锚索框架加固高边坡技术的有效性,为高边坡的防护治理设计及施工提供了可靠的技术经验。     

YQM预应力锚固体系挤压锚施工技术

通过工程实例介绍了挤压锚的施工原理、操作工艺，并提出在施工过程中应严格控制挤压锚的质量。     

In vitro evaluation of screws and suture anchors in metaphyseal bone of the canine tibia

OBJECTIVE: To compare ease of insertion, load to failure, and mode of failure of cortical and cancellous screws, BoneBiter, IMEX, and TwinFix suture anchors in canine metaphyseal tibial bone. STUDY DESIGN: Experimental biomechanical study. ANIMALS: Canine cadaveric tibias. METHODS: One investigator inserted all anchors and subjectively evaluated ease of placement. Anchor systems were loaded to failure along axis of insertion with audio-video recording to determine failure mode. RESULTS: BoneBiter was the most difficult anchor to insert successfully. Mean+/-SD loads to failure were cancellous screw (711+/-193 N), IMEX 4.7 mm 18 g wire (661+/-163 N), IMEX 4.0 mm 18 g wire (661+/-165 N), cortical screw (635+/-184 N), BoneBiter #5 Kevlar suture (393+/- 109 N), and TwinFix 5.0 mm #2 polyester (267+/-73 N). No significant differences were noted among the cortical screw, cancellous screw, IMEX 4.7 and 4.0 mm, all of which were significantly (P<.001) greater than BoneBiter and TwinFix . Failure modes were pullout of bone, suture-wire breakage, eyelet breakage, or no failure to 1000 N: screws (18,0,0,2), IMEX (18,1,1,0), BoneBiter (2,8,0,0), and TwinFix (0,10,0,0). CONCLUSIONS: Fixation devices were user friendly, with the exception of BoneBiter. Mode of failure is dependent on suture material and anchor design. Cortical and cancellous screws, and IMEX anchors with 18 g wire have significantly greater load to failure compared with BoneBiter and TwinFix suture anchors. CLINICAL RELEVANCE: Based on load to failure, ease of use, design characteristics, and cost, IMEX anchors may have advantages over other comparable soft tissue fixation devices.     

An in vitro study to determine the effectiveness of a patellar ligament/fascia lata graft and new tibial suture anchor points for extracapsular stabilization of the cranial cruciate ligament-deficient stifle in the dog

OBJECTIVE: (1) To determine whether an extracapsular patellar ligament/fascia lata graft would provide stability in the cranial cruciate ligament (CrCL)-deficient stifle comparable with that of the intact stifle. (2) To determine if different tibial anchor points would enhance stability of the CrCLdeficient stifle when compared with the standard fabellar-tibial suture (FTS) placement. STUDY DESIGN: Experimental. ANIMALS: Twenty-eight canine cadaver hind limbs. METHODS: Stifles were mounted in a jig and tested between loads of -65 and 80 N. After testing the intact CrCL, 4 stabilization techniques were tested after CrCL transection: lateral graft technique (LGT) and 3 FTS with different tibial anchor points. RESULTS: There were no significant differences in displacement between the LGT and standard FTS, between the LGT and the intact CrCL, or between the FTS and the intact CrCL, in either the Securos or the Screw-washer experiments. Stiffness of the intact CrCL was significantly greater than that of any stabilization technique and the cut CrCL. The standard FTS showed the least displacement of all suture stabilization techniques. Differences in stiffness were not significant between the suture stabilization techniques. CONCLUSIONS: Securely anchored, the LGT results in a reduction in drawer motion similar to that of the intact CrCL and the standard FTS. Altering the tibial anchor point for the FTS does not improve stiffness or enhance stabilization of the CrCL-deficient stifle. CLINICAL RELEVANCE: The LGT could be used for the treatment of CrCL ruptures in the dog. A clinical study is recommended.     

Mechanical performance of a screw-type veterinary suture anchor subjected to single load to failure and cyclic loads

OBJECTIVE: To characterize the mechanical performance of a veterinary bone anchor under static and cyclic loads. STUDY DESIGN: Mechanical testing study. ANIMALS: Cadaveric canine humeri. METHODS: Humeri (6 pairs) were collected from skeletally mature dogs (mean [+/-SD] age, 17.2+/-2.1 months; weight, 20.8+/-1.5 kg). Bone anchors were inserted in the proximal metaphysis using nylon, and were longitudinally extracted. For the opposite humerus, anchors were subjected to longitudinal cyclic load (50% of the load at failure of their pair) for 1200 cycles then longitudinally loaded to failure. Anchors were then installed in a similar and adjacent area of these 2(nd) humeri with nylon and cyclically tested perpendicular to the axis of anchor insertion (100% of the longitudinal holding power of their pair) for 1200 cycles, then perpendicularly loaded to failure. Paired t-tests were used to compare holding power before and after longitudinal cyclic testing. RESULTS: Longitudinal holding power of the screw-type anchor in the proximal humerus was 385+/-30 N. Anchor pullout was the only mode of failure. Anchors in the paired humeri did not fail after 1200 cycles of 50% longitudinal loading, and post-cycle holding strength was not different (335+/-87 N; P=.32). Perpendicularly loaded anchors did not fail after 1200 cycles of 100% of opposite longitudinal holding strength, and had post-cycle perpendicular holding strengths of 514+/-72 N. Suture breakage was the mode of failure. CLINICAL RELEVANCE: Bone anchor holding strength is dependent on orientation of suture load. Screw-type bone anchor holding strength was not affected by longitudinal cyclic loading, and holding strengths of approximately 385 N can be expected in metaphyseal bone of large-breed mature dogs. Perpendicularly loaded anchors have higher failure loads, and holding strength of approximately 514 N can be expected in metaphyseal bone of the proximal humerus.     

Two techniques for supplementing interlocking nail repair of fractures of the humerus, femur, and tibia: results in 12 dogs and cats

OBJECTIVE: To describe 2 devices for improving stabilization of inadequately stabilized interlocking nail (ILN) repairs of the humerus, tibia, and femur in dogs and cats. STUDY DESIGN: Prospective study. ANIMALS: Twelve client-owned dogs and cats. METHODS: Two devices to further stabilize ILN repair of inadequately stabilized diaphyseal fractures were developed. Device 1 was an axial extension for the ILN that was connected to a conventional type I external skeletal fixator (ESF) with a short connecting bar. Device 2 had hybrid ILN bolt/ESF pins that were used to lock the ILN and serve as the pins for a type I ESF. Devices were used at the initial surgery when the stability of ILN repair was considered inadequate based on palpable fracture segment movement, insufficient medullary canal filling of the ILN at the fracture site, or when the ILN was used in a buttress mode. Outcome was obtained by recheck examinations, radiography, and telephone interview. RESULTS: Device 1 was applicable to fractures of the humerus and femur, but was not used for fractures of the tibia because the ILN extension would have interfered with the stifle. No gross loosening of the ILN/ESF extension connection to the ILN occurred. Device 2 was easily placed and used in the humerus, femur, and tibia. Device 2 allowed removal of the ILN interlock to one or both main fracture segments non-invasively. Clinically, both devices added stability compared with ILN repair alone. Both devices facilitated controlled destabilization of the fracture repair as healing progressed. Complications of pin tract infection, and premature hybrid bolt/ESF pin loosening resulting in premature ESF removal each occurred in 1 patient. Four of 28 hybrid ILN/ESF pins were grossly loose at 4- or 6-week postoperative recheck examinations. Outcomes were excellent (9), good (1), fair (1), and poor (1). CONCLUSIONS: Inadequately stabilized ILN repair of fractures can be stabilized by use of either device, both of which also permit controlled destabilization of the repair during healing. Device 2 can be used when non-invasive removal of the ILN interlock is desired during healing. CLINICAL RELEVANCE: These 2 devices should be considered as alternative methods for stabilization of inadequately stabilized ILN repairs in dogs and cats, or when controlled destabilization of an ILN fracture repair is desired.