In order to strengthen the seismic design and diagnosis of glulam building structures, and improve the accuracy and reliability of building modal analysis, this paper uses the designed glulam frame structure as a research object to conduct experimental investigation on its dynamic properties. On the one hand, a computational modal analysis is carried out using ANSYS to determine the modal shapes and modal parameters of the glulam frame structure. On the other hand, transient excitation, steady-state contact excitation and steady-state non-contact excitation methods are used to test and analyze the experimental modalities of the field-built larch glulam frame structure. The research results show that the three experimental modal methods can all measure the biaxial(xy-) first-order bending, first-order torsion, and second-order bending modes of the glulam frame structure. The vibration shapes and modal frequencies are all consistent. The results of computational modal analysis and experimental modal analysis are combined in this article. Since the elastic constant input of components is measured by grading, the frequency values of the computational mode are larger. The error of the two analyses is about 15%. In the first-order bending mode in the x- and y-directions, both the computational and experimental modes show the characteristics of greater local stiffness in the gusset. In the uniaxial (x- or y-) torsional mode, the computational mode not only reflects the torsional characteristics of the upper beam region, but also shows first-order bending mode of the column, which is also consistent with the experimental mode.
According to the characteristics of ploughing extrusion forming and the theory of metal cutting, the wear and damage mechanism, common wear and damage forms and causes of multi-tooth tools in ploughing extrusion forming are analyzed. Then, the correctness of the analysis of tool wear and damage mechanism and common wear and damage forms is verified by field cutting experiments. At the same time, the phenomena and causes of workpiece stagnation and cracks in the process of ploughing and extrusion forming were obtained through experiments. Finally, the reasonable processing parameters of ploughing and extrusion forming multi-tooth cutting tool were obtained.
Sliding experiments lubricated with hydroxyl silicate magnesium particles as additive were performed under ambient condition and different loads by using an AMSLER friction and wear tester. The surface topographies and compositions of worn surface of 45 steel rings were analyzed by SEM and EDAX. The experimental results show that the friction load had great effect on generation of the frictionally-formed protective coating. No protective coating formed on the worn steel surface under lower friction load. However, a smooth and continuous protective coating can be developed on the worn surface of the steel when the friction load is high enough. The chemical composition of the protective coating is roughly the same as the additive. The additive can be fractured, stretched and flowed along the sliding direction under high contacting stress and instantaneous flash temperature, which result in coating being formed.
Wooden packaging boxes and pallets are used in a wide range of applications. In this work, LVL from the same source and batch were used as the base material. After dynamic detection and grading, they were divided into two grades (A and B), according to their differences in elastic modulus. The packaging boxes and pallets of the same specifications were designed and manufactured as the research objects. Four mechanical properties studies and related analyses were performed. The three mechanical tests showed different deflection values of the two packaging boxes A and B, and the maximum error was 6.93%. In the rotational edge drop test, the edges of the nether end rails of the two grades of LVL boxes were damaged to varying degrees. Additionally, the nails at the connection between the middle longitudinal beam and the bottom plate also appeared to be pulled out, and the parts made of B-grade LVL were more obvious. The results show that the dynamic detection and quality grading for LVL can effectively distinguish the material grade. The grading results were consistent with the mechanical properties of the LVL packaging boxes and pallets of corresponding grades, which are suitable for use in production lines.
Aiming at the problems of sway and collision caused by tilt, swing and uneven distribution of wire rope tension in the hoisting process of hoisting in the well, this paper designs a control system of wire rope tension balance and attitude adjustment of the hoisting disk based on the inverse kinematics model and the force feedback balance model. Through the position information of the hanging plate, the wire rope displacement information and the wire rope force feedback information to adjust the length and tension of the wire rope, and the finite element software Adams is used to establish the lifting plate balance mechanism pulley sling model, which simulates the lifting plate during the lifting movement. The attitude leveling and tension balancing process. Simulation results show that: in the process of lifting the sling, the wire control sling balancing mechanism can quickly level the sling and effectively reduce the swing of the sling. IntroductionAt present, lifting equipment is mainly divided into four types: light and small lifting equipment, bridge type, boom type and cable type according to the structure.Flexible steel wire rope not only has high tensile strength, but also has good receiving capacity, which is convenient for storage and transportation. However, in the operation platform of multi-rope synchronous hoisting, the swing of flexible steel wire rope and uneven force often lead to the tilt of the operation platform, which may easily lead to the safety accident of the collision between the hoisting platform and the shaft wall. In recent years, a lot of research work has been done on the leveling and anti-sway lifting of vertical lifting platforms in China, and some research results have been obtained. On the leveling problem of the platform, Zhu Bao [1] used the spatial geometric decomposition method to establish a spatial model and derived a horizontal decomposition algorithm, which would automatically level the rotary platform without re-adjusting the sensitive orientation of the horizontal sensor. Zhai yujian[2] and zhang fang[3] both adopted multi-point support platform for attitude leveling, and established PLC control system for leveling by controlling Angle error and position error analysis. Yi jianqiang [4] designed a fuzzy controller by using the four-rope suspension mechanism, which can adjust and even the tension of the suspension platform. Shao Xingguo [5] designed the attitude leveling and wire rope tension equalization controller based on the inverse kinematics model, and realized the attitude leveling and tension balance of the hanging plate by adjusting the running speed of the four stable motor. Zhang Fuming [6] uses the PLC control system to synchronously lift and suspend the five lifting points on the disc. In the anti-swing aspect of the platform, Du Wenzheng [7], Wang Xiaojun [8] designed a method for crane positioning and anti-sway based on fuzzy control. Wang Keqi [9] regards the crane as a non-linear coupling system with insufficient excitation, decoupling and linearizing i...
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