Railway Crane Boom’s Bionic Design Based On Bamboo’s Cross-Sectional Microstructure

With the changing from Rectangle, Keystone, Polygon, large rounded rectangle to oval, now we have a consensus that oval cross-section is the best form for crane boom, and this form is much like the shape of bamboo stalks. From a macro perspective, the improvement process of crane boom’s cross-section structure is the process of mimicking bamboos’oval shape. Conversely, if we take bamboo stalks as the perfect design objects, this can give a good reason why we have a bottleneck in crane boom’s design and why we couldn’t have a more effective boom’s cross-section structural, because the oval cross-section is nearly to perfect. Thus, the author decides to change the way of traditional design thought, and consider the design of boom’s cross-section from the microscopic view. Based on the cross-sectional microstructure of bamboo, the author designs a bionic boom, and then, uses ANSYS Workbench as the computing, comparing, optimization tool, proved the validity of this paper’s bionic ideas. The main contents are as follows:Based on the similarity analysis between crane boom and bamboo, the author has a conclusion that crane boom’s bionic design meets the basic requirements. Then the author studies the mechanical properties and microstructure of bamboo, and the relationship between them, and has a conclusion that the key point for bamboo’s perfect mechanical properties is the microstructure of bamboo having multilayered vascular bundles. Based on the characteristic of boom and bamboo’s microstructure, the author designs two bionic booms, one is the boom with two layers of steel and each layer having same sectional shape, another is the boom with two layers of steel and each layer having different sectional shape. According to some reasons, the author finally chooses the boom with two layers of octagon steel as the basic analysis model.In the Geometry module of ANSYS Workbench, the author builds the bionic boom and traditional boom with the same parameters; then in the Static Structural module, the author calculates the two boom with same methods, including same meshing parameters, same loads, and same supports; by analyzing the strength parameters, the author finds that bionic boom is better in this indexes:maximum stress, average stress and overall stress; by analyzing the Stiffness and Local Stability, the author finds that the bionic boom is also better than traditional boom. So, through the comparison, it’s clearly that the bionic idea is useful.Based on the Design Explorer module of ANSYS Workbench, the author makes some optimizing for bionic boom. In the optimizing process of each steel layer’s thickness, the author sets the thickness as independent variable, sets the minimum stress difference as optimization target and chooses CCD method to create test sample points, chooses Standard Response surface-full 2nd order Polynomials method to create response surface, chooses Screening method to iterative calculation. The results show that the optimization analysis is necessary and it can make the materials more effective. In the optimizing process of stiffeners’ thickness, the author sets strength and local stability as compare index content, then designs some experiments, In the experiments, the author make the thickness changes from 5mm to 20mm, and generate an experiment point every 0.5mm, then summarizes the calculation results, it shows that the strength follows the thickness linearly, but the local stability nearly has no relationship with stiffeners’ thickness.A preliminary study on stiffeners arrangement. In the study of stiffeners angle, firstly, according to boom’s real work situation and overall stability, the author chooses the boom’s webs to set different angles stiffeners, then creates the boom models with 0°,30°,45°,60°, 90° stiffeners. After calculation, the author finds that boom with 0° stiffeners has best performance on overall stability. In the study of stiffeners density, the author builds two models, one is boom with stiffeners uniformly distributed, and another is boom with stiffeners unevenly distributed. The study results show that the stiffeners density has a great influence on boom’s overall stability.