Influence of dent on residual ultimate strength of 2024-T3 aluminum alloy plate under axial compression

Drop-weight impact tests were conducted on 2024-T3 aluminum plates with five types of impactors, and then the effects of the dent on the residual ultimate strength of the 2024-T3 specimens were investigated through axial compression tests. Results indicate that with increase in dent depth, the five types of dents affect the ultimate strength of the plate in different trends. Nevertheless, other than the plate global deflection caused by impacting, the dent itself has unremarkable effect on the ultimate strength. The mathematical expressions are derived regarding the relationship between impact energy factor and the dent depth factor as well as the compressive ultimate strength reduction rate and the dent depth factor.

A Biomechanical Comparison of Conventional versus an Anatomic Plate and Compression Bolts for Fixation of Intra-articular Calcaneal Fractures

The purpose of this study was to compare the biomechanical stability obtained by using our technique featured an anatomical plate and compression bolts versus that of the conventional anatomic plate and cancellous screws in the fixation of intraarticular calcaneal fractures.Eighteen fresh frozen lower limbs of cadavers were used to create a reproductive Sanders type-Ⅲ calcaneal fracture model by using osteotomy.The calcaneus fractures were randomly selected to be fixed either using our anatomical plate and compression bolts or conventional anatomic plate and cancellous screws.Reduction of fracture was evaluated through X radiographs.Each calcaneus was successively loaded at a frequency of 1 Hz for 1000 cycles through the talus using an increasing axial force 20 N to 200 N and 20 N to 700 N,representing the partial weight bearing and full weight bearing,respectively,and then the specimens were loaded to failure.Data extracted from the mechanical testing machine were recorded and used to test for difference in the results with the Wilcoxon signed rank test.No significant difference was found between our fixation technique and conventional technique in displacement during 20-200 N cyclic loading(P=0.06),while the anatomical plate and compression bolts showed a great lower irreversible deformation during 20-700 N cyclic loading(P=0.008).The load achieved at loss of fixation of the constructs for the two groups had significant difference:anatomic plate and compression bolts at 3839.6±152.4 N and anatomic plate and cancellous screws at 3087.3±58.9 N(P=0.008).There was no significant difference between the ultimate displacements.Our technique featured anatomical plate and compression bolts for calcaneus fracture fixation was demonstrated to provide biomechanical stability as good as or better than the conventional anatomic plate and cancellous screws under the axial loading.The study supports the mechanical viability of using our plate and compression bolts for the fixation of calcaneal fracture.

Locking compression plate+T-type steel plate for postoperative weight bearing and functional recovery in complex tibial plateau fractures

Complex tibial plateau fractures can seriously affect quality of life and physical and mental health of patients.The anatomical relationship between the proximal tibial bone and soft tissue is complex,resulting in different types of tibial plateau fractures.Violent trauma can lead to displaced fracture,serious soft tissue injury,and potentially,dislocation of the knee joint.Therefore,tibial plateau fractures are extremely unstable.AIM To assess the use of locking compression plate(LCP)+T-type steel plate for postoperative weight bearing and functional recovery of complex tibial plateau fractures.METHODS Ninety-seven patients with complex tibial plateau fractures who underwent surgery at our hospital were selected for retrospective study.Forty-nine patients had been treated with LCP+T-type steel plate limited internal fixation(study group),and 48 patients with bilateral ordinary steel plate support(control group).The operation process index,postoperative rehabilitation related index,Rasmussen score of the knee joint,tibial plateau varus angle(TPA),tibial plateau retroversion angle(PA),and surgical complications of the two groups were compared.RESULTS The operation time and intraoperative bone graft volume in the study group were lower than those in the control group(P<0.05).There were no significant differences in surgical bleeding,anterior external incision length,postoperative drainage,hospital stay duration,and fracture healing time between the groups(P>0.05).There was no significant difference in the TPA and PA angle between the groups immediately and 18 mo after surgery(P>0.05).At 12 mo after surgery,the Rasmussen scale score was higher in the study group than in the control group(P<0.05).There was no significant difference in the Rasmussen scale score at 18 mo after surgery,and the radiology score at 12 and 18 mo after surgery,between the two groups(P>0.05).The postoperative complication rate in the study group(3.77%)was lower than that in the control group(15.09%;P<0.05).CONCLUSION LCP+T-type steel plate internal fixation has advantages in terms of minimizing trauma and enabling early postoperative functional exercise,promoting functional recovery and lower limb weight-bearing,and reducing postoperative complications.

Supracutaneous Locking Compression Plate for Grade I &II Compound Fracture Distal Tibia—A Case Series

Background: Supracutaneous plating using a locking compression plate (LCP) as an external fixator in compound periarticular areas is facilitated by the development of anatomical plates. The soft tissue around the distal tibia is easily compromised by trauma and subsequent operative fracture treatment posing a definitive challenge in the distal tibia compound fractures. The purpose of this report is to describe our successful results using the metaphyseal locking compression plate (LCP) as an external fixator in the treatment of Grade I & II compound fractures of distal tibia. Methodology: A total of five (05) patients underwent “supracutaneous plating” of the tibia using a metaphyseal locking compression plate. Average age was 36 years. Regular screw tract dressings were done. Average period of follow-up was 15 months. Results: The plate was in situ for an average of 24 weeks. There were no clinically significant screw site infections. In all five patients the plate was kept in place until there was complete consolidation both clinically and radiologically. At the latest follow-up (average 15 months), all patients were fully weight bearing with a fully healed tibia. All patients were infection-free with well-healed wounds. Conclusion: Routinely, after initial debridement and temporary bony stabilization is provided by external fixation in compound fractures of the distal tibia with significant soft tissue injury. Most external frames for the lower leg are bulky and cumbersome, causing significant problems for the patient. To circumvent these issues, we have successfully used an anatomically-contoured supracutaneous metaphyseal locking compression plate as external fixator in a series of five patients for grade I & II compound fracture of the distal tibia.

The Effects of Bone Screw Configurations on the Interfragmentary Movement in a Long Bone Fixed by a Limited Contact Locking Compression Plate

The locking compression plates (LCP) are efficient tools in open reduction and internal fixation (ORIF), especially in osteoporotic bones. Two important factors of screw density and screw position can affect the functionality of the bone plate. Several studies have assessed the influence of the screw configurations on the bone-plate stiffness, but the effects of screw positions on the interfragmentary strain, εIF of LCP construct have not been investigated yet. In this study, finite element method was used to investigate the influence of screws number and position on the interfragmentary strain of LCP-femur system for a mid-shaft fracture. Results of this study showed that by insertion of screws closer to the fracture site, εIF decreases by 2nd degree polynomial function versus screw position, but by adding the screws from the ends of the plate, or by moving and placing the screws towards the fracture site, the reduction of εIF will be linear. Results of this study were compared and are in agreement with some studies in the literature, even though their scope was mostly stability of the bone-implant system, whereas our scope was focused on the interfragmentary strain.

A Simple Empirical Formula for Predicting the Ultimate Strength of Ship Plates with Elastically Restrained Edges in Axial Compression

An investigation is conducted on the static ultimate limit state assessment of ship hull plates with elastically restrained edges subjected to axial compression.Both material and geometric non-linearities were considered in finite element(FE)analysis.The initial geometric imperfection of the plate was considered,while the residual stress introduced by welding was not considered.The ultimate strength of simply supported ship hull plates compared well with the existing empirical formula to validate the correctness of the applied boundary conditions,initial imperfection and mesh size.The extensive FE calculations on the ultimate strength of ship hull plates with elastically restrained edges are presented.Then a new simple empirical formula for plate ultimate strength is developed,which includes the effect of the rotational restraint stiffness,rotational restraint stiffness,and aspect ratios.By applying the new formula and FE method to ship hull plates in real ships,a good coincidence of the results between these two methods is obtained,which indicates that the new formula can accurately predict the ultimate strength of ship hull plates with elastically restrained edges.

Application of proximal femur locking compression plate for unstable four part intertrochanteric fractures

Objective To evaluate the clinical results of proximal femur locking compression plate (LCP) for unstable four-part intertrochanteric femoral fractures.Methods Clinical data of53patients wiith unstable four-part intertrochanteric

Comparison of effect of locking compression plate internal fixation and reconstruction plate fixation for treatment of mid-shaft clavicular fracture

Objective:To compare the effect of locking compression plate internal fixation and reconstruction plate fixation for the treatment of mid-shaft clavicular fracture.Methods: In this study, the medical records of 68 patients with mid-shaft clavicular fractures treated in our department from May 2014 to May 2017 were retrospectively analyzed. 32 patients in the control group received the reconstruction plate fixation, while 36 patients in the observation group received the locking compression plate internal fixation. Patients were followed up for 12 months, thereafter, various indicators including operative indexes, Constant-Murley (CM) score, disability of arm shoulder and hand (DASH) score, activities of daily living (ADL), and complications were compared between groups.Results: The incision length, intraoperative blood loss, operation time, and fracture healing time of the observation group were significantly lower than the control group (P<0.05). The postoperative CM scores of the two groups were significantly increased, moreover, the scores of muscle strength, daily life and activity were significantly in the observation group were higher than those of the control group (P<0.05), and no difference was found in the pain degree (P>0.05). There was a decrease trend in the DASH score and an increase trend in the ADL score in both groups, while both indexes were better in the observation group than in the control group (P<0.05). The total incidence of complications in the observation group was significantly lower than that in the control group (8.33% vs 18.75%,P<0.05).Conclusion: Compared with the reconstruction plate fixation, locking compression plate internal fixation has the advantages of more mini invasive, better amelioration of shoulder joint function and less complication for patients with mid-shaft clavicular fractures.

Effect of locking compression plate internal fixation on the injury extent and bone metabolism of Robinson 2A and 2B middle clavicular fractures

Objective:To investigate the effect of locking compression plate internal fixation on the injury extent and bone metabolism of Robinson 2A and 2B middle clavicular fractures.Methods:Totally 80 cases of patients with Robinson 2A and 2B middle clavicular fractures admitted to our hospital between March 2017 and January 2019 were divided into the control group(n=41)receiving conventional kirschner wire internal fixation and the observation group(n=39)receiving locking compression plate internal fixation according to the operation plans.The differences in serum contents of inflammatory factors,oxidative stress indexes and bone metabolism indexes were compared between the two groups of patients before patients entered operating room,24 h after surgery and 48 h after surgery.Results:Before patients entered operating room,there were no statistically significant differences in the serum contents of inflammatory factors,oxidative stress indexes or bone metabolism indexes between the two groups(P>0.05).At 24 h and 48 h after surgery,serum inflammatory factors interleukin-1(IL-1),interleukin-17(IL-17),high-sensitivity C-reactive protein(hs-CRP)and tumor necrosis factorα(TNF-α)contents in the observation group were lower than those in the control group;serum reactive oxygen species(ROS)and lipid hydroperoxide(LHP)contents were lower than those in the control group,while catalase(CAT)and glutathione peroxidase(GSH-Px)contents were higher than those in the control group;serum N-terminal propeptide of procollagen type I(PINP),bone gla protein(BGP)and alkaline phosphatase(ALP)contents were higher than those in the control group,while N-telopeptide of typeⅠcollagen(NTX),C-telopeptide of typeⅠcollagen(CTX)and tartrate-resistant acid phosphatase 5b(TRACP5b)contents were lower than those in the control group(P<0.05).Conclusion:Locking compression plate internal fixation can reduce the postoperative trauma extent and help promote the fracture healing in patients with Robinson 2A and 2B middle clavicular fracture.

Effect of Locking Compression Plate on the Treatment of Limb Fracture and the Effect of Operative Success Rate and Postoperative Recovery Time

Objective:To analyze the effect of locking compression plate on the success rate of operation and the time of postoperative recovery.Methods:120 patients with limb fractures from March 2018 to March 2020 were randomly divided into control group(60 cases)and observation group(60 cases).The control group was treated with plate screw internal fixation,The observation group used locking compression plate internal fixation,Compare the effect of treatment,the success rate of operation and the time of postoperative recovery.results:compared the effective rate of the two groups,the observation group(93.33%)was significantly higher than the control group(75.00%).Compared with the two groups,the success rate of operation and the time of postoperative recovery,the observed composition power was higher than that of the control group,and the postoperative recovery time was lower than that of the control group,P<0.05.Conclusion:The use of locking compression plate for the treatment of limb fracture can significantly increase the probability of successful operation,shorten the recovery time after operation,the overall curative effect is ideal,and the clinical popularization value is high.

Postoperative Fracture Healing Effects of Locking Compression Plate for the Treatment of Limb Fractures

Objectives To study the effects of applying locking compression plates in the treatment of patients with limb fractures on postoperative fracture healing.Methods:115 patients with limb fractures who were treated in our hospital from November 2019 to November 2020 were selected.In order to study the effective treatment method,the random-number table method was used in this study to divide the patients into two groups,namely the experimental group and the control group,and the locking compression plate treatment method and the pure plate and screw internal fixation treatment method were administered respectively to study their clinical application effects.Results:Compared with the control group,patients in the experimental group had a lower incidence of complications,shorter hospitalizations and shorter recovery time.Meanwhile,the experimental group had a better quality of recovery,and all data were significantly different from those of the control group,P<0.05,the intervention effect of the experimental group was better.Conclusion:The application of the locking compression plate in the treatment of patients with limb fractures is more conducive to promoting the postoperative healing of the patients'fractures,reducing the incidence of postoperative complications,and promoting the rapid recovery of patients,which has positive significance for clinical development.

Ultimate Compressive Strength Computational Modeling for Stiffened Plate Panels with Nonuniform Thickness

The aim of this paper is to develop computational models for the ultimate compressive strength analysis of stiffened plate panels with nonuniform thickness.Modeling welding-induced initial deformations and residual stresses was presented with the measured data.Three methods,i.e.,ANSYS finite element method,ALPS/SPINE incremental Galerkin method,and ALPS/ULSAP analytical method,were employed together with existing test database obtained from a full-scale collapse testing of steel-stiffened plate structures.Sensitivity study was conducted with varying the difference in plate thickness to define a representative(equivalent)thickness for plate panels with nonuniform thickness.Guidelines are provided for structural modeling to compute the ultimate compressive strength of plate panels with variable thickness.

Compressive Behavior of Steel Members Reinforced by Patch Plate with Welding and Bonding

Repair and reinformcement of aged civil steel structures is one of the important issues for maintaining and using them for a long term. For repair and reinforcement of deteriorated civil steel structures due to fatigue and corrosion, patch plate reinforcement is widely applied. Bolting is generally used because of easy quality control and many construction achievements. However, bolting has downsides including holes made and weight increase. Welding is considered to overcome these demerits but in reality the application of welding is unsatisfactory due to the possibility of fatigue crack occurring from the welded part. In this study, a patch plate strengthening system of welded joint assisted with bonding has been proposed. The compressive behaviors of weld-bond jointed specimen were investigated by a series of experiments and FE analysis. It was confirmed that use of welding and bonding was effective to enhance compressive strength of specimen, due to better load-carrying capacity of patch plate compared with sole use of welding.

VIBRATIONS OF STEPPED ONE-WAY THIN RECTANGULAR PLATES SUBJECTED TO IN-PLANE TENSILE/ COMPRESSIVE FORCE IN Y-DIRECTION ON WINKLER'S FOUNDATION

Differential equations of free/forced vibrations of n_step one_way thin rectangular plates subjected to in_plane tensile/compressive force in y_direction on Winkler's foundation are established by using singular functions, their general solutions solved for, expression of vibration mode function and frequency equation on usual supports derived with W operator. Influence functions for various cases deduced here may also be used to solve problems of static buckling or stability for beams and plates in relevant circumstances.

Vibration of a Two-Layer“Metal+PZT”Plate Contacting with Viscous Fluid

The present work investigates the mechanically forced vibration of the hydro-elasto-piezoelectric system consisting of a two-layer plate“elastic+PZT”,a compressible viscous fluid,and a rigid wall.It is assumed that the PZT(piezoelectric)layer of the plate is in contact with the fluid and time-harmonic linear forces act on the free surface of the elastic-metallic layer.This study is valuable because it considers for the first time the mechanical vibration of the metal+piezoelectric bilayer plate in contact with a fluid.It is also the first time that the influence of the volumetric concentration of the constituents on the vibration of the hydro-elasto-piezoelectric system is studied.Another value of the present work is the use of the exact equations and relations of elasto-electrodynamics for elastic and piezoelectric materials to describe the motion of the plate layers within the framework of the piecewise homogeneous body model and the use of the linearized Navier-Stokes equations to describe the flow of the compressible viscous fluid.The plane-strain state in the plate and the plane flow in the fluid take place.For the solution of the corresponding boundary-value problem,the Fourier transform is used with respect to the spatial coordinate on the axis along the laying direction of the plate.The analytical expressions of the Fourier transform of all the sought values of each component of the system are determined.The origins of the searched values are determined numerically,after which numerical results on the stress on the fluid and plate interface planes are presented and discussed.These results are obtained for the case where PZT-2 is chosen as the piezoelectric material,steel and aluminum as the elastic metal materials,and Glycerin as the fluid.Analysis of these results allows conclusions to be drawn about the character of the problem parameters on the frequency response of the interfacial stress.In particular,it was found that after a certain value of the vibration frequency,the presence of the metal layer in the two-layer plate led to an increase in the absolute values of the above interfacial stress.

预应力螺栓连接钢板约束混凝土圆柱轴压性能研究

螺栓连接钢板(BST)约束混凝土圆柱,由于钢板可拆卸及更换,较钢管约束混凝土具有更好的可恢复性。以BST约束混凝土圆柱为研究对象,提出在两片拼装钢板间预留间隙,并拧紧螺栓而对其施加预压应力的方法。以施加的预压应力和径厚比为参数,对6根BST约束混凝土圆柱及1根无约束混凝土圆柱进行轴心受压试验。结果表明,预留间隙并拧紧螺栓的方法能对核心混凝土有效施加预压应力,使钢板在加载前即对核心混凝土形成有效约束。相较于无约束混凝土圆柱,同条件的施加预压应力的BST约束混凝土圆柱峰值应力最大提高74.5%,且残余强度最大能保持在峰值应力的92.3%。相较于未施加预压应力的BST约束混凝土圆柱,施加预压应力的BST约束混凝土圆柱预压应力越大,峰值应力越大,最大可提高18%;径厚比越小,BST约束混凝土圆柱峰值应力越大,但随着预压应力增大,峰值应力提高的幅度降低。

3D打印导板定位微球囊压迫术治疗原发性三叉神经痛的临床随机对照研究

目的 分析3D打印导板定位微球囊压迫术(PMC)与常规PMC治疗原发性三叉神经痛(PTN)的临床疗效及安全性。方法 选择廊坊市人民医院神经外科2020年1月—2022年12月收治的80例PTN患者作为研究对象,使用随机数字表法分成观察组与对照组各40例。对照组行常规PMC治疗,观察组行3D打印导板定位PMC治疗。比较两组手术一般情况、术后即刻疗效、手术前后不同时点疼痛视觉模拟量表(VAS)评分、术后12个月复发情况及术后并发症情况。结果 观察组首次穿刺成功率97.50%显著高于对照组27.50%(P<0.05)。观察组穿刺成功时间、手术总时间、住院时间、住院费用均显著优于对照组(P<0.05)。观察组术后即刻总有效率97.50%与对照组95.00%比较,差异无统计学意义(P>0.05)。两组术前及术后1、2周的VAS评分组间比较(P>0.05)显示,观察组术后4周时疼痛VAS评分显著低于同期对照组(P<0.05)。术后12个月,观察组合计复发率5.00%显著低于对照组合计复发率20.00%(P<0.05)。观察组术后面部麻木、咬肌无力、口唇疱疹发生率与对照组比较,差异无统计学意义(P>0.05)。结论 3D打印导板定位PMC较常规PMC能显著提高首次穿刺成功率,缩短穿刺时间与手术总时间,且术后即刻疗效及远期疗效均显著。

装配式带夹芯保温槽型玻璃钢-钢板-槽钢-混凝土组合剪力墙轴压性能研究

提出一种装配式带夹芯保温槽型玻璃钢-钢板-槽钢-混凝土组合剪力墙,设计3个具有不同配筋形式和混凝土种类的墙板试件进行轴心受压试验,获得墙板在轴压作用下的破坏模式、荷载-位移曲线、荷载-应变曲线、承载力储备系数、延性系数、材料利用率等性能指标。通过ABAQUS有限元分析软件对墙板进行参数化分析,研究内嵌钢板强度和厚度对其轴压性能的影响。结果表明,墙板具有良好的承载力储备能力和延性性能;混凝土中掺入1%体积比的钢纤维可显著提高墙板内混凝土的抗拉性能,使混凝土强度得到更加充分的利用,布置钢筋可以显著提高墙板延性;墙板的承载力和延性随内嵌钢板厚度和强度的增加而增大,强度为Q355、厚度为4、6mm时,墙板材料利用率更高。提出适用于该类墙板的轴压承载力设计公式,考虑钢板屈曲和截面组合效应的墙板轴心受压承载力设计公式计算结果较精确。

压燃式二冲程对置活塞转盘发动机一维性能仿真

二冲程对置活塞转盘(2S-OPCP)发动机是一种新型发动机.该发动机使用凸轮转盘机构替代了传统发动机中的曲柄连杆机构,这种特殊的结构使转盘发动机具有功率密度高、体积小和结构简单等优点.发动机两侧的凸轮转盘存在相对转角,通过改变凸轮相对转角θ可以改变发动机的有效压缩比及换气正时,从而影响发动机的性能.根据转盘发动机的结构特点及工作过程搭建了一维热力学仿真模型,并使用试验数据对模型的缸内压力曲线进行了标定.随着θ改变,发动机的扫气过程及性能表现都会发生变化.当θ在0°~10°内变化时,发动机的换气过程有所改善,给气比在θ=7°时最高,提升了3.5%.同时,在θ达到4°后,指示燃油消耗率(ISFC)开始逐渐增加,ISFC最高增加了3.5%(θ=10°);而平均有效压力(IMEP)最高增加了3.3%(θ=4°),之后随着θ的上升,IMEP开始降低.

基于能力保护的新型拉压双向限位装置设计方法研究

为保护通航渡槽结构缝之间止水不被破坏,提出替代止水受力的新型拉压双向限位装置.此装置力学特征类似销轴耳板连接结构,此类结构有多重破坏模式的弱点.为克服此弱点,结合《钢结构设计标准》(GB 50017—2017)中销轴耳板连接结构设计方法,在该装置的静力设计中,基于能力保护的设计思想提出了以单一销轴弯曲破坏为该装置破坏模式的设计方法.基于实体有限元数值模拟,分析了加载过程中此装置整体与各部件的受力-变形曲线特点.结果表明:以外荷载-整体变形量曲线不出现塑性特征为依据,判定装置的静力承载力大于设计外荷载、设计方法偏于安全;通过销轴的外荷载-弯曲变形量曲线与限位装置的外荷载-整体变形量曲线显现的非线性特征相一致以及板的外荷载-整体变形量曲线在加载过程中基本保持线性状态,说明板是被保护构件、装置破坏模式为单一的销轴弯曲破坏.研究结果表明此设计方法现实可行.