Removable hanging structure designed to hold the rope and Performance Optimization
|School||Central South University|
|Course||Mechanical Manufacturing and Automation|
|Keywords||detachable grip modal analysis stress and strain analysis kinematic analysis holding force|
To deal with the drawbacks of the existing gravity-based grip, such as heavy self-weight, bulky size, easy to get jammed when derailing, incapable of making turns on a slope and easily cracked reamed holes, as well as the lack of integral theoretical system to aid design procedure, the kinematics and structural characteristics of the grip is studied in this study. The operation principles of the 4-bar mechanism, the core part of the grip, are proposed. The holding force of the grip is designed based on the theoretical calculation and the force amplification efficiency of the 4-bar mechanism is characterized with the concept of lever ratio. The dimensions of the grip’s core parts are determined by the design of a proper lever ratio. The envelop angle is calculated with the jaw theory, where the grip performance is characterized with an envelop coefficient. A proper envelop coefficient ensures both the stability during the griping and the flexibility during the derailing. Wheel carrier and friction board are installed to supply the balance point and power for the grip to run after derailing. The reliability of the proposed theoretical calculation results is analyzed through both the simulation and the experiment, providing data and theory support to the development and design of grips.According to the requirement of system performance of detachable grip, assemble accuracy of digital model is assembled and its assembly accuracy is checked in Pro/E. It provides a spatial concept and assembly data for optimum grip design. The kinematics of the grip are analyzed in Pro/Mechanical to obtain the motion state of each part and detect the possible spatial interference or the excessive motion, which provides three dimensional data to the open angle of the movable clip to guarantee the realization of kinematics performance of the grip. Simulation is carried out with ANSYS software to investigate the distribution of stress and strain in the grip. According to the simulation results, the critical sections in the movable clip where stress concentration occurs are improved by thickening or increasing the transition angle to guarantee the reliability of the critical sections in the grip.In the experimental study, the concept of indirect force measurement is introduced to measure the distortion in the steel clip of the grip, corresponding to the pressure of the clip, which is equal to the gripping force of the grip. After a serial of measurements, the average lever ratio was calculated, which was used to verify the theoretical design and calculation, as well as the reasonableness of boundary condition settings for modal analysis simulation. Through the strain experiments, the total strain in key parts of inner and outer clip, i.e. clip head and reamed holes, were measured to check the stress and strain distribution obtained through the simulation and define the critical sections in the grip’s core parts. The measurements were also used to enhance the load capacity of the critical sections in later optimization process.The systematic analysis and investigation are carried out on the detachable grip through the theoretical, the simulation and experimental study to provide theoretical data for the optimization of movable clip. Theoretical calculations are used to guide the grip design. Simulations are carried out to optimize the structure and dimensions of the grip. Experiments are carried out to verify the optimized design and its accuracy. The work completed in this thesis provides a beneficial reference for the industry.