Seismic behavior of hybrid coupled shear wall with replaceable U-shape steel coupling beam using terrestrial laser scanning

The hybrid coupled shear wall (HCW) with replaceable coupling beam (CB) is an optimal component to recover buildings promptly after a severe earthquake. However, the reinstallation may be difficult or impossible with an identical CB because of the inelastic relative dislocation between two wall piers. This study proposes a novel HCW with different reinforcement ratios in the connection, which was tested under cyclic loading. After the test, the bolt holes can be located through terrestrial scanning, which is then utilized to fabricate a new CB that can accommodate the deformation between two wall piers. The newly replaced HCW system was also tested. As a result, all virgin test specimens fail in web fracture and show a significant inelastic chord rotation of 0.2 rad, exhibiting an excellent energy dissipation capacity. Meanwhile, the new method to locate the bolt holes after the test is feasible. The replaced HCW fails in the pull-off of anchor bars and shows poor seismic behavior due to the unpatched concrete cover in the connection. To improve the energy dissipation for the replaced HCW, high-strength grouting in the connection can be used and high-strength material can be used to replace the usual anchor bolts.

Automated optimum visualization system for construction drawing reading

The task of reading drawings on construction sites has significant efficiency and cost problems. Recent products utilising laser projectors attempt to address the issue of drawing comprehension by projecting full scale versions of the drawings onto 3D surfaces, giving an in-place representation of the steps required to complete a task. However, they only allow projection in red or green at a single brightness level due to the inherent constraints of using a laser-based system, which could cause problems depending on the surface to be projected on and the ambient conditions. Thus, there is a need for a solution that is able to adjust the visualisation parameters of the displayed information based on the surface being projected onto. This study presents a system that automatically changes the visualisation parameters based on the colour and texture of the current surface to make drawings visible under any planar-like surfaces. The proposed system consists of software and hardware, and the software algorithm contains of two parts 1) the optimisation run that computes and updates the visualisation parameters and 2) the detection loop which runs continually and checks if the optimisation run needs to be triggered or not. In order to verify the proposed system, tests on 8 subjects with 4 background surfaces commonly found on site were performed. The test subjects were timed to find 10 bolt holes projected onto the surface using the optimisation system, which was then compared to a control case of black lines projected onto a white background. The system allowed users to complete the task on the real-world backgrounds in the same time as the control case, with the system resulting in up to a 600% decrease in recognition time on some backgrounds.

Machining Path Optimization of 3C Locking Robots Using Adaptive Ant Colony Optimization

The motion smoothness of 3C locking robot directly affects the machining performance. Improving the motion smoothness can optimize the motion trajectory and reduce the processing time. In this paper, a novel machining path optimization model including motion smoothness is built by employing the coordinate boundary of velocity and acceleration after evaluating the machining motion smoothness of the 3C locking robot. Secondly, based on the creation of the ant colony of adaptive function algorithm, the optimization model of the 3C locking robot in the situation of fixed bolt hole position and floating bolt hole position is resolved. Lastly, the proposed approach collects and analyses a huge amount of data to enable robots to make on-the-fly decisions in the middle of production, even when faced with unexpected circumstances. In the Spark distributed environment, we use the conventional K clustering technique to improve the final output utilizing clustering means. The results show that the machining path optimization of fixed hole considering the motion smoothness improves the smoothness but extends the machining path; the cooperative machining path optimization of multiregion floating bolt holes can significantly improve the motion smoothness and effectively reduce the length of the path. The research results provide theoretical support and design guidance for designers.

PROBLEMS OF HIGH-SPEED RAIL FLAW DETECTION

The main factors that reduce the quality of non-destructive testing of rails during high-speed scanning are considered. The most significant factors are the quality and volume of obtaining primary information about the condition of the monitored rails. It is shown that, at high-speed (up to 120 km/h) control, the compression of the defect location zone is clearly manifested and the length of the areas with acoustic contact violations increases. Analysis of real flaw diagrams of diagnostic complexes shows that with an increase in the scanning speed, the length of the location zone even from such large reflectors in the rails, such as bolt holes, significantly decreases. The average length of the instability zone of the bottom signal over the welded joints of the rails also increases significantly. The compression of the location zones of the reflectors can be compensated by expanding the aperture of the ultrasonic transducers. Improving the quality of the acoustic contact requires further improvement of the design of the search system and the systems for supplying the contacting liquid to the transducers, depending on the scanning speed. The Magnetic Flux Leakage(MFL) method can effectively detect defects in the rail head up to 20 mm deep at high speeds. Mathematical modeling of the magnetic flux in the controlled rails is performed. This allows us to start creating a new rail magnetization system with an increased interpole distance for high speeds. The introduction of modern methods for processing a significant flow of flaw detection information using neural networks requires the formation of a large sample base of training signals from real defects in different sections of rails. This is a complex task in its own right. For the first time, the issues of checking the operability of flaw detection devices in real control conditions are raised. Testing of ultrasonic equipment at high speeds is proposed to be carried out with the help of special electronic-acoustic simulators of defects. They are installed on different surfaces of the rails on which the diagnostic complexes pass. Operational quality control of ultrasonic rail inspection can be evaluated by statistical analysis of signal parameters from structural elements (bolt holes). The choice between the monitoring performance and the required reliability of detecting rail defects must be made based on the results of real passes of diagnostic complexes at operating scanning speeds.

Nonlinear Dynamic Performance of a Bolt-Disc Rotor with the Position Error of Circumferential Bolt-Holes

The bolt-holes in the assembly discs are designed to limit the circumferential displacement of bolts for the bolt-disc rotor. The position error of circumferential bolt-holes is created in a three-dimensional model of bolt-disc rotor. The distribution of nonuniform stress and deformation is acquired according to finite element approach. Static results demonstrate that the position error of bolt-holes leads to obvious concomitant unbalances including constant mass eccentricity and speed-variant bending under the influence of large tightening force. When these unbalance factors are taken into consideration, dynamic performance such as instability areas and nonlinear motions are analyzed by Newton iterative process and a prediction-correction calculation method. Dynamic results show that rotor flexure enables the systematic stability decreased obviously because of this position error. There is a special phenomenon compared to monobloc rotor that the vibration amplitude proceeds to rise when rotating speed exceeds the critical speed. Moreover, the allowable position error of bolt-holes is obviously smaller than that of monobloc rotor and uneven tightening is a feasible way to reduce adverse effects on the dynamic properties when position error appears. This work proposes a static-dynamic approach to investigate the dynamics of imprecise bolt-disc rotor and establishes the relationship between machining error and dynamic features.

Анализ параметров ультразвуковых сигналов при высокоскоростном контроле рельсов

The results of studies of changes in the parameters of ultrasonic (US) signals with an increase in the speed of rail testing are presented. Signals from rail bolt holes were selected as test reflectors. It is shown that the holes closest to the rail joint are not fully sounded, and the signals from them cannot be used as test reflectors. For a full assessment of the decrease in the quality of non-destructive testing of rails with an increase in the scanning speed, it is proposed to use the integral parameter of the analyzed reflector. A noticeable decrease in this parameter at high speeds requires a trade-off when choosing between productivity and quality rail testing. The proposed technique can be used to assess the efficiency of operating and newly created flaw detection systems. The necessity of improving the methods of sounding the first bolt holes of joints and correcting regulatory documents for high-speed testing of rails is substantiated.

Structural Design Research Through Finite Element Method (FEM) for a Compressor Disc

Compressor Discs are subjected to various loads like pressure load, tensile, compressive, buckling, temperature, gravity, etc. during its operation. There are load bearing members and non-load bearing members. The load bearing members are critical components of the disc. Due to these loading condition radial and hoop stresses are generated in the discs. When these stresses exceed yield strength of the material failure occurs. To determine the various stresses acting on a gas turbine compressor disc rotating with constant velocity, initially the Disc is modeled and analyzed using Commercial FEA codes focused on bolt holes and nominal stresses on the cracked disc (a corner crack at a hole and then a through-thickness crack between two holes) are determined. These Stresses can be accounted for the development of advanced crack growth model which can predict the propagation of crack from the critical location of the rotating disc.