Applied Mechanics and Materials Vols. 670-671

Abstract: Joint member stiffness in a bolted connection directly influence the safety of a design in regard to both static and fatigue loading as well as in the prevention of separation in the connection. Thus, the accurate determination of the stiffness is of extreme importance to predict the behavior of bolted assemblies. In this paper, An analytical 3D axisymmetric model of bolted joints is proposed to obtain the joint stiffness of Bolted Joints. Considering many different analytical models have been proposed to calculate the joint stiffness, the expression based force equilibrium can be a easy way to choose the best expression for the joint stiffness as a judgment criteria.

Abstract: The CA method of how to select target equipment in a whole plant for a PdM program is proposed in the paper. A set of evaluation standards using criticality analyzing approach are established. This method is applied in many plants and is verified with the actual condition of plant requirement. The evaluation results fit for the criticality of all plants and will be different in different plants because of service and functional role played even for the same type machine.

Abstract: Relationship between bolt rib type, rib height, rib spacing and anchor performance have been studied through laboratory drawing test method. Bolt rib type plays a significant impact on the bolt anchor performance. The bigger of the bolt rib height and higher of the drawing force, the better of the anchor performance, but when the rib reach a certain height, drawing force will not increase obvious with the continue increase of rib height. Drawing force will different if the rib spacing is different, and with the increase of rib spacing, drawing force will increase at first and then reduce. When the rib spacing is about 30mm, the drawing force will get the maximum and the best of the anchor performance.

Abstract: Pretension is the critical factor for cable supporting, but phenomenon of pretension loss exists in engineering practices. Tests of pretension loss carried out in Luan Zhangcun Mine show that the length and diameter of cables, anchorage, and degree of tension, tensioning equipments, and other factors will affect pretension loss of cables; the appropriate solution to reduce pretension loss is proposed. Ultra-tensioning 25% can ensure that the pretension meets the design requirements.

Abstract: A damage evolution model is presented for fatigue life prediction of metallic structures. This model is formulated based on damage mechanics and the irreversible thermodynamics framework developed by LEMAITRE and CHABOCHE. Using this model, the fatigue lifetime can be predicted both in the high cycle fatigue (HCF) regime and the low cycle fatigue (LCF) regime. Based on the energy theory and material fatigue test data, the plastic strain threshold for damage initiation was modified for HCF and LCF respectively. The damage evolution parameters were determined according to the fatigue test results of standard specimens. A damage mechanics-finite element full-couple method was adopted to simulate the process of fatigue damage evolution. The numerical simulation of fatigue lives were compared with the fatigue tests of 2A12-T4 open-hole plates and good agreement was obtained.

Abstract: In the aeronautic field, ductile structure usually undergoes local fracture under complicated service loading conditions, which may triggers collapse of a structure. As a result, it is very essential to study the mechanism of fracture initiation and propagation of ductile materials especially under complex stress states. In this paper, a comparative study of fracture patterns of a load-bearing lug joints structure under several loading conditions with two ductile fracture models is performed by using the commercial finite element platform ABAQUS/ Explicit through a user material subroutine VUMAT. The numerical comparisons using two ductile fracture models in predicting failure of load-bearing lug joints structure shows that modified X-W fracture model agrees well with the experimental observation under complex stress states.

Abstract: This in-plane behavior of two one-half scale reinforced concrete (RC)-brick masonry walls with opening before and after retrofitting with basalt fiber reinforced polymer (BFRP) is investigated. One specimen was served as the reference without any strengthening scheme; another one was first tested to the severely damaged level, and then retrofitted with BFRP in a mixed strengthening configuration on two sides. Both of these specimens were tested under in-plane constant vertical load and cyclic lateral load. Test results are analyzed in terms of failure mode, maximum shear strength, ultimate drift, energy dissipation and equivalent viscous damping coefficient, which indicated that the use of BFRP composite material can effectively improve both the strength and deformation capacity of the damaged masonry wall as well as changing failure mode and maintaining the wall’s integrity.

Abstract: Xinchang tailings dam is used as an object and the software named Slide is utilized to operate numerical simulation, and then the three conditions (normal operating mode, flood conditions, the special conditions) of tailings dam are analyzed to determine the stability. The conclusions are as follows: tailings dam have been built to 80m height, both to meet regulatory requirements, so the dam is stable; but if continue to increase the height to 85m, tailings dam stability coefficient reduced to special conditions 1.032, less than the standard value 1.05, does not meet the national regulatory requirements, the maximum limit of a height of about 80m.

Abstract: In this paper, the key technique involved in life prediction of aeroengine’s high temperature component for creep and fatigue/creep interaction, namely, the life prediction methods for high temperature component are discussed systematically. The essential thinking、features and development direction of the theories are commented in detail. All the results obtained are valuable to engineering applications.

Abstract: The research of fatigue properties of the butt welded joint, though a large number of fatigue tests are need to be carried out, has significant influence to hoisting equipment’s design, development and using safety. This paper conducted a study on simulating the fatigue properties of widely used steel Q345 butt welded joint’s by finite element method based on the improved linear equivalent structural stress theory. The originally massive amount of fatigue tests and data processing could be saved. In order to ensure the accuracy of the fatigue modeling, a batch of Q345 butt welded joints were prepared for the fatigue tests which is used to contrast with the modeling result. The stress distribution under different load situation and the fatigue life of the joints, which have profound reference significance to hoisting machinery industry, can be acquired through modeling.