WSP特殊螺纹接头油井管的研制

介绍了WSP特殊螺纹接头的基本结构和设计思想,运用有限元方法,重点论述了密封设计和连接强度设计的方法和准则,并通过全尺寸试验进行了验证。计算和试验结果表明,该接头具有先进的螺纹形式、合理的扭矩台肩和金属/金属密封结构,有效地克服了API圆螺纹和偏梯形螺纹的不足,螺纹达到了与管体等强度,气密封能力达到了管体的内壁屈服压力。研究结果可以为开发更多适合油气田实际的特殊螺纹接头油井管提供参考。     

A force control high-order single-step-β method (HSM) for substructure pseudo-dynamic testing

This paper proposes a new technique which introduces the high-order single-step-β method(HSM)into the experimental study on the substructure pseudo-dynamic testing(SPDT).The technique is based on the proposed concept of equivalent shear stiffness which can meet the requirement of the HSM algorithm.A study is done to theoretically validate the technique by the numerical analysis of two-storey shear building structure,in comparison of the proposed substructure pseudo-dynamic testing algorithm with the central difference method(CDM).Then,a full-scale SPDT model,the three-storey frame-supported reinforced concrete short-limb masonry shear wall structure,is designed and tested to simulate the seismic response of the corresponding six-storey structure and verify the proposed force control HSM technique.Meanwhile,the techniques of both stiffness correction and force control are suggested to control algorithmic error,control error and measurement error.The results indicate that the force control HSM can be used in the full-scale multi-degree-of-freedom(MDOF)substructure pseudo-dynamic testing before descent segment of structure restoring force properties.     

H型截面单层单跨钢框架火灾行为试验

对2榀H型截面单层单跨钢框架进行了火灾行为的足尺试验研究.全部试验采用自行研制的火灾试验炉,试验结果表明炉子性能稳定,使用方便.试验中考虑了不同受火工况对钢框架火灾行为的影响.通过试验得出了钢框架温度场分布和变形的变化规律.试验结果表明:火灾下,梁柱全部受火的单层单跨钢框架(节点受到保护)破坏方式为钢柱压屈破坏,破坏位置在受到保护的钢节点下部的钢柱上.试验研究为今后钢结构火灾行为的研究提供依据.     

底框砌体剪力墙震损房屋抗震加固拟动力子结构试验

在完成了3层足尺底框配筋砌块短肢砌体剪力墙震损房屋损伤程度的评估、加固的基础上,通过对加固后的3层房屋进行拟动力抗震性能试验,研究了震后受损结构构件所用加固方法的适用性和加固对恢复结构抗震性能的效果,为寻求震损结构加固修复的方法提供理论依据,并为汶川地震受损底框房屋的结构修复提供参考。     

Identification schemes for unmanned excavator arm parameters

Parameter identification is a key requirement in the field of automated control of unmanned excavators （UEs）. Furthermore, the UE operates in unstructured, often hazardous environments, and requires a robust parameter identification scheme for field applications. This paper presents the results of a research study on parameter identification for UE. Three identification methods, the Newton-Raphson method, the generalized Newton method, and the least squares method are used and compared for prediction accuracy, robustness to noise and computational speed. The techniques are used to identify the link parameters （mass, inertia, and length） and friction coefficients of the full-scale UE. Using experimental data from a full-scale field UE, the values of link parameters and the friction coefficient are identified. Some of the identified parameters are compared with measured physical values. Furthermore, the joint torques and positions computed by the proposed model using the identified parameters are validated against measured data. The comparison shows that both the Newton-Raphson method and the generalized Newton method are better in terms of prediction accuracy. The Newton-Raphson method is computationally efficient and has potential for real time application, but the generalized Newton method is slightly more robust to measurement noise. The experimental data were obtained in collaboration with QinetiQ Ltd.     

大直径焊接空心球节点足尺试验研究

通过对某体育中心屋盖拱形桁架支座的焊接空心球节点的足尺模型试验,获得了该节点的应力应变分布情况和极限承载力.为了探讨理论设计方法,采用AN SY S有限元分析软件,采用she ll143壳单元建模,同时考虑几何和材料双重非线性进行有限元分析.结合试验结果和有限元分析结果,验证有限元模型和分析方法的合理性,并对球节点的受力性能和承载力进行评价,同时为复杂节点设计提供参考.     

Fracture Assessment of Carbon Fibre/Epoxy Reinforcing Rings through a Combination of Full-Scale Testing, Small-Scale Testing and Stress Modeling

Carbon fibre/epoxy rings are used as radial reinforcement for polymer bearing elements with nominal diameter 250 mm functioning under 150 MPa. Full-scale static and dynamic testing revealed no catastrophic failure for loading to 400 MPa, although there was circumferential splitting of carbon fibres at the machined top edge causing counterface wear under sliding. A combined numerical–experimental analysis was applied for design improvement with a representative small-scale qualification test on the real ring geometry, inducing additional stress concentrations compared to ASTM standards. Full-scale modelling revealed high radial–axial shear stresses (33 MPa) in non-hydrostatically loaded zones, while it increased towards 104 MPa under hydrostatic load conditions. The former is the most critical and should be simulated either on a small-scale unidirectional compression test or on a representative short beam shear test, respectively, measuring the radial–axial or radial–tangential shear strength. A relation between both small-scale states of stress was experimentally and numerically studied, experiencing that the composite ring has lower radial–tangential shear stress compared to radial–axial shear stress as a different hydrostatic stress state is observed in the bulk of the composite ring. As a compressive test is however more difficult to perform than a short-beam-shear test, a representative design criterion for shear fracture is determined from failure at 27 kN normal load in a short-beam-shear test. Finally, fracture is avoided by optimising the cross-sectional geometry of the composite reinforcing ring and close control of the processing parameters.     

Large-eddy simulation of wind effects on a super-tall building in urban environment conditions

A combined study of large-eddy simulation (LES), wind tunnel testing and full-scale measurement is conducted for the evaluation of wind effects on a super-tall building in a complex urban area. To validate the numerical simulations, the wind tunnel experiments including synchronous multi-pressure and high-frequency force balance model tests are conducted in a boundary layer wind tunnel laboratory. The numerical predictions are then compared with the experimental results, demonstrating that the LES can provide comparable predictions of the wind effects on the super-tall building. Furthermore, the cross-validation of the predicted displacement responses by the LES against the wind tunnel and full-scale measurements are presented and the agreement among them is reasonably good. The main objective of this study is to explore an effective numerical approach for the accurate estimation of wind effects on tall buildings in urban environment conditions and promote the practical use of the LES in the wind-resistant design of complex structures.     

Comparing rutting of airfield pavements to simulations using Pavement Analysis Using Nonlinear Damage Approach (PANDA)

This study presents the rutting performance results of full-scale pavement test sections subjected to F-15E and C-17 aircraft wheels at two different temperatures. Pavement structures for the tests were constructed under shelter in the U.S. Army Engineer Research and Development Center's (ERDC) pavement test facility. The full-scale test results are used to validate viscoelastic, viscoplastic and hardening-relaxation constitutive relationships implemented in the Pavement Analysis Using Nonlinear Damage Approach (PANDA) model. PANDA is a mechanistic-based model which incorporates nonlinear viscoelastic, viscoplastic, hardening-relaxation, viscodamage, moisture-induced damage and ageing constitutive relationships. Results of dynamic modulus and different repeated creep-recovery laboratory tests are analysed to extract the parameters associated with viscoelastic, viscoplastic and hardening-relaxation constitutive relationships implemented in PANDA. Once calibrated, PANDA is used to predict the rutting performance observed in full-scale pavement test sections. The simulation results illustrate that PANDA is capable of predicting the rutting of airfield pavements subjected to heavy aircraft wheel loads at intermediate and high temperatures. It is shown that PANDA successfully predicts the effect of shear flow and upheaval at the edges of the wheel. The data from simulation suggested that PANDA, once calibrated, can provide insight into the critical locations of tensile and compressive stresses within the pavement structure. PANDA simulations not only provide a tool for evaluating existing structures, but also can be used in designing more sustainable pavement structures and materials.