Bolt Force Research Articles

数値解析と実験による低温流体用管フランジの熱・力学挙動の評価

Sealing of contained fluids is the primary criteria required for pipe flange connections. Recently, there is a rapid rate of increase in the use of low temperature fluids, and leakage related accidents have been reported. Its leakage mechanism seems to be different from the case in pipe flange connections at elevated temperatures. In this paper, it is examined how the leakage of low temperature fluids occurs, in which a pipe flange connection is cooled by liquid nitrogen. The variations of bolt temperature and bolt force are continuously measured. Experimental results show that the bolt force is reduced to as low as about 65% of the initial value. Next, a numerical method based on three-dimensional FEM is proposed to simulate the cooling process. Numerical results are in good agreement with those from experiments. Applying the numerical method to the pipe flange connections for LNG, showed a bolt force reduction of 70% of the initial value. The numerical method proposed in this paper is expected to be applied to cases of different low temperature fluids under various flow conditions.

Analytical Study on the Prying Action Force and Axial Tensile Stiffness of High-Strength Bolts Used in an Unstiffened Extended End-Plate Connection

단부판 접합부는 다양한 형태로 보-기둥 모멘트 접합부에 적용되고 있다. 이러한 단부판 접합부는 단부판의 두께 및 길이, 고장력 볼트의 개수 및 직경, 고장력볼트의 게이지 거리, 고장력볼트의 지레작용력, 용접부의 치수 및 길이 등에 따라서 상이한 거동특성, 강성 및 강도, 에너지소산능력의 변화를 나타낸다. 따라서 이 연구는 단부판의 두께 변화에 따른 인장측에 체결된 고장력볼트의 지레작용력 및 축방향 인장강성을 파악하고, 단부판의 거동특성에 영향을 미치는 이러한 변수들을 예측하기 위한 해석모델을 제안하기 위하여 진행하였다. 이를 위하여 이 연구에서는 단부판의 두께만을 변수로 선택하여 비보강 확장단부판 접합부에 대한 3차원 비선형 유한요소해석을 수행하였다. The end plate connection is applied to beam-column moment connections in various forms. Such end plate connection displays changes in the behavioral characteristics, strength and stiffness, and energy dissipation capacity based on the thickness and length of the end plate, the number and diameter of the high strength bolt, the gauge distance of the high strength bolt, prying action force of the high strength bolt, and dimensions and length of the welds. Accordingly, this study has apprehended the axial tensile stiffness and prying action force of the high strength bolt connected on the tensile side based on the difference in thickness of the end plate, and was conducted to propose an analysis model for the prediction of such variables that affect the operating properties of the end plate. To achieve this, this study has conducted a three-dimensional non-linear finite-element analysis of the unstiffened expanding end plate connection by selecting only the thickness of the end plate as the variable.

Research on the Assembly Pattern of MMC Bolted Flange Joint

In a Metal-to-Metal Contact (MMC) bolted flange joint the stress of sealing surfaces is constant. It canwithstand higherbolt load. So, under the operating conditions of high temperature, high pressure or their fluctuations, the sealing effect of MMC bolted flange joints is better than of floating (FLT) bolted flange joints. According to the structure characteristics of MMC bolted flange joints, a new tightening method (SH-Method) was recommended in this work.The bolt forces during the tightening process of a MMC bolted flange joint with SH-Method were calculated and analyzed with the finite element analysis Software ANSYS. The calculating model and results were experimentally verified. Both calculating and experimentally results showed, the new tightening method ‘SH-Method’has the advantages of fewer steps, simpler operation, more uniform bolt force, and better sealing effect, compared to the star pattern and the alternative pattern #3 of ASME PCC-1, in which only the pattern methods for FLT flange joints are recommended.

Bolt Pull-Out Tests of Anchorage Body under Different Loading Rates

Based on the force analysis and mechanical transmission mechanism of grouting bolts, the self-developed test apparatus for interfacial mechanics is used to study the distribution rule of axial force and interfacial stress of bolts in anchorage body. At the same time, pull-out tests of anchorage body are simulated with the particle flow code softwarePFC2D, and stress distribution and failure patters are researched under different loading rates. The results show that the distribution of axial force and interfacial shear stress is nonuniform along the anchorage section: axial force decreases, shear force increases first and then decreases, and the maximum value of both of them is closed to the pull-out side; with the increase of loading rates, both of axial force and interfacial shear stress show a trend of increase in the upper anchorage section but changes are not obvious in the lower anchorage section, which causes serious stress concentration; failure strength of pull-out and loading rates show a linear correlation; according to loading rates’ impact on the anchoring effect, the loading rates’ scope can be divided into soft scope (v<10 mm/s), moderate scope (10 mm/s <v< 100 mm/s), and strong scope (v>100 mm/s).

Mechanism Analysis of Anchor Bolt and Cable Synergistic Action in Coal Roadway Support

Aiming at the current situation of anchor bolt and cable arrangement in mine roadway support, the paper analysis the mechanical characteristics and mechanism of bolts and cables, and numerical simulation method is used to comparison and analysis of pre-tension distribution characteristics under different anchor bolt-cable arrangement. The research indicated that separate anchor bolt-cable layout in different sections, anchor bolt and cable force stable equilibrium, coordinate with each other, at this time roadway surrounding rock of shallow and deep pretension distribution more reasonable, can play a role of bolt anchor cable synergistic action, and form the best pre-tension load-bearing structure, which is helpful to keep the stability of coal roadway.

Proposal of Methodology and Calibration of Dynamometers for Quantification of Forces in Anchor Bolts

Anchor bolts in heavy machines of metallurgical plants are often, from the point of view of their carrying capacity, limiting factor in increasing productivity. This paper presents some possibilities of increasing strength of anchor bolts using numerical and experimental methods of mechanics. Proposed and verified procedures allow determining the actual stress states during tightening the anchor bolts and nuts and reduce dynamic loads in bolts as well as in operating machines.

토크전단형 고력볼트의 토크계수 변동에 따른 체결축력 확보방안에 관한 연구

Torque control method and turn of nut method are specified as clamping method of high strength bolts in the steel construction specifications. Quality control of torque coefficient is essential activity because torque control method, which is presently adopted as clamping method in domestic construction sites, is affected by variation of torque coefficient. The clamping of torque shear bolt is based on KS B 2819. It was misunderstood that the tension force of the TS bolt was induced generally at the break of pin-tail specified. However, the clamping forces on slip critical connections do not often meet the intended tension, as it considerably varies due to torque coefficient dependent on the environmental factors and temperature variables despite the break of the pin tail.This study was focused to evaluate the effect of environmental factors and errors of installing bolts during tightening high strength bolts. The environmental parameters were composed of 'wet' condition, 'rust' condition, 'only exposure to air' condition. And the manufacture of trial product was planned to identify the induced force into the bolts. The algorithm for a trial product was composed of the relation between electricity energy taken from torque shear wrench and tension force from hydraulic tension meter.

Ultimate tensile deformation and strength capacities of bolted-angle connections

This paper reports an experimental study of 31 bolted double-angle connections under a pure tension load. Failure modes such as angle rupture and bolt tension rupture were observed. The test results included load versus deformation curve, ultimate tensile deformation and strength. A new equation for predicting axial deformation capacity was proposed based on a regression analysis. The merits of a frame model and a truss model were investigated in predicting the ultimate tensile strength of the tested connections. A component-based model was then proposed to predict the load versus deformation curve of the connection. It was found that the current AISC equation on the prying action of bolts seriously underestimate the prying force of bolts when used with angles. A new prying equation was thus proposed for the design of bolts to ensure that the ductility of bolted-angle connections would be achieved.

Splitting capacity of bottom rail in partially anchored timber frame shear walls with single-sided sheathing

Plastic design methods can be used for determining the load-carrying capacity of partially anchored shear walls, where hold-downs are not provided. In order to use these methods, a ductile behaviour of the sheathing-to-framing joints must be ensured. Since the forces in the anchor bolts and the sheathing-to-framing joints do not act in the same vertical plane, the bottom rail will be subjected to bending and shear in the crosswise direction, and splitting of the bottom rail may occur. In this article, results of two experimental programmes on the splitting capacity of the bottom rail due to uplift in partially anchored shear walls are presented. Two brittle failure modes occurred during testing: (1) a crack opening from the bottom surface of the bottom rail; and (2) a crack opening from the edge surface of the bottom rail along the line of the sheathing-to-framing joints. The results show that the distance between the edge of the washer and the loaded edge of the bottom rail has a decisive influence on th...

Stress and fatigue life analyses of a five-piece rim and the proposed optimization with a two-piece rim

A five-piece rim and a two-piece bolt-connected rim were investigated to examine stress levels and fatigue lives on critical regions. The finite element models of the rim/tire assemblies were developed and validated through tire engineering data and previously validated modelling approaches. The rim/tire assemblies were simulated under two conditions, (1) application of a 23,100kg static load followed by a 24.14km/h travelling speed and an 82° wheel angle, and (2) application of a 26,900kg static load followed by an 8.05km/h travelling speed and an 82° wheel angle. The results revealed that travelling and steering speeds were the key factors in causing high stresses and bolt tension forces. Compared to the five-piece rim, the two-piece rim decreased the maximum stresses by over 30% for both loading conditions; consequently the fatigue lives were increased by over two orders of magnitude. The maximum bolt forces for the two-piece rim were estimated to be 195,680N and 111,360N separately.

Study on the Influence of Air Resistance on the Mechanical Structure Based on the Theory of Elastic-Plastic Mechanics

This paper establishes two-dimensional mathematical model and three-dimensional mathematical model of the mechanical structure elastic-plastic mechanics and according to Hooke's law and Drucker postulate analyzes the plastic relationship of the elastic-plastic mechanics. The first part of the paper introduces the parameter setting of finite element analysis of elastic-plastic mechanics. The second part establishes computer simulation model of elastoplastic. Finally, it analyzes bolt force using ANSYS software and applies it to computer simulation of elastoplastic force and air resistance of gymnast in the process of action showing which provides technical reference for the training of gymnasts.

Support technology for mine roadways in extreme weakly cemented strata and its application

For the engineering geology conditions of bad mine roadway roof and floor lithology in extremely weak cemented strata, the best section shape of the roadway is determined from the study of tunnel surrounding rock displacement, plastic zone and stress distribution in rectangular, circle arch and arch wall sections, respectively. Based on the mining depth and thickness of the coal seam, roadway support technology solutions with different buried depth and thickness of coal seam are proposed. Support schemes are amended and optimized in time through monitoring data of the deformation of roadway, roof separation, I-beam bracket, bolt and anchor cable force to ensure the long-term stability and security of the roadway surrounding rock and support structure. The monitoring results show that mine roadway support schemes for different buried depth and section can be adapted to the characteristics of ground pressure and deformation of the surrounding rock in different depth well, effectively control the roadway surrounding rock deformation and the floor heave and guarantee the safety of construction and basic stability of surrounding rock and support structure.

Effects of nonlinearity on determination of bolt forces for the operational state of a bolted flange connection

Modelling and calculations of an asymmetrical bolted flange connection at the operational stage are presented. The physical model of the joint is based on a flexible flange element that is connected with a rigid support by means of hybrid elements, which substitute bolts. Between the flange element and the support, the linear Winkler model of a contact layer is taken into account. The bolted flange connection is preloaded and then subjected to an eccentric normal load. The influence of nonlinearity of the contact layer between the joined elements on computational values of bolt forces has been investigated. Results of calculations for several different values of the joined element’s thickness are described

Interaction Mechanism between Two Large Rock Caverns

Long-term stability of geotechnical structures is critical to any engineering design. Design of underground structures is initially planned using empirical approaches based on the rock mass–classification system. This design is mainly based on limited data obtained from boreholes and surface geological mapping. However, this design needs to be continuously updated based on the information gathered as the excavation work progresses. Over the last few years, geotechnical monitoring has emerged as a major engineering tool for engineers to review and update their existing design configuration based on the actual behavior of excavated rock mass. This paper presents a case study of the interaction of two large unlined rock caverns that were excavated using a drill-and-blast technique with a heading-down benching approach. The mechanical response of the two caverns was numerically modeled and studied in terms of the stress-deformation behavior of the excavated caverns and rock support installed, taking into account the actual sequence of heading and benching followed during parallel excavation activity at one of the construction sites. It was observed from the analysis that the crown/wall junction is sensitive to displacements under both good and fair rock-mass conditions. Limited comparative study was also carried out between the measured and calculated displacements; this showed encouraging results. Progressive buildup of forces in the rock bolts and development of the stresses in pillars were also studied as part of the interaction response of two caverns.

654 温度変動時のガスケット付きフランジ締結体のボルト軸力変化に与える初期締付力及び温度サイクルの影響

654 温度変動時のガスケット付きフランジ締結体のボルト軸力変化に与える初期締付力及び温度サイクルの影響

Improving CNC Machine Tool Geometric Precision Using Manufacturing Process Analysis Techniques

With the ever increasing demands for higher and higher accuracy on modern CNC equipment, the manufacturing processes for machining and assembling the structural components are an increasingly important factor in establishing a geometrically correct machine tool. Specifically, flatness, perpendicularity, parallelism, and straightness of interfacing surfaces determine whether the machine tool's basic accuracy. Exhibiting less geometric error allows other errors such as thermal growth, ballscrew pitch error, and control error to be isolated and more easily corrected.The geometric errors are predominately a factor of the machine tool machining and assembly process. Multiple orientations during fixturing in both assembly and machining result in significant distortions to the final assembled product. These are a result of cutting forces, fixturing deformations, gravity deformations, and bolt force deformation. By analyzing each process in detail using virtual simulation techniques, a high-fidelity model of the corresponding error at each manufacturing step can be achieved that is not physically measurable due to constraints of measurement equipment. Using simulated data as offset data in the machining process as well as in the jig and fixture design ensures a geometrically accurate final product.

652 ボルト軸力のばらつきが内圧作用下の非石綿ガスケット付き管フランジ締結体の密封性能に及ぼす影響

652 ボルト軸力のばらつきが内圧作用下の非石綿ガスケット付き管フランジ締結体の密封性能に及ぼす影響

The Effect of Axial Bolt Force and Gasket Properties on Sealing Performance of Flange Connection

The Effect of Axial Bolt Force and Gasket Properties on Sealing Performance of Flange Connection

604 ガスケット締結体の高温時軸力挙動評価

604 ガスケット締結体の高温時軸力挙動評価

656 高温におけるフランジ締結体のボルト軸力変化とガスケット変形挙動

656 高温におけるフランジ締結体のボルト軸力変化とガスケット変形挙動