| The essence of the structure is to transfer the load from its point of application to the point at which it is reacted.At present,the commonly used method,finite element analysis method focuses on the stress and strain at discrete points of the structure and can not reflect the working mechanism in the structure.While the force flow method can directly describe the process of load transfer and distribution in the structure,reflect the working efficiency and guide the design and optimization of structures.In spite of this,there are few studies on force flow at home and abroad,and people’s knowledge of force flow is mostly on the conceptual level.Based on the background,the objective of this paper is to improve the existing method of force flow analysis to make it more suitable for practical engineering applications,and put forward evaluation indices of structure transmission efficiency based on the concept of force flow,which lays the foundation for quantitative evaluation of structure transmission efficiency and optimization of structural performance.Study in this paper presents the following parts of work:(1)The force flow analysis method and force transmission efficiency evaluation method of the continuum structure are proposed.By comparing and analyzing the characteristics of several existing force flow analysis methods,it is determined that the load path method is used as the basic method of this paper.In order to obtain the ideal planar structure force flow analysis method,improving the load path method to solve the problem that the original method needs to decompose the external force in the orthogonal direction to draw the force flow separately.Considering the characteristics of thin shell structure,the strain energy ratio is used to reflect the internal force of the thin shell element,and the force flow analysis of the thin shell structure is realized by combining the strain energy ratio and the force path.On this basis,putting forward evaluation indices based on the ratio of the shortest force transmission path to the actual force transmission path,and the effectiveness of this method is verfied by some examples.(2)The force flow analysis method and force transmission efficiency evaluation method of the rod structure are proposed.According to the force characteristics,the rod structure is divided into truss structure and rigid frame structure.For the truss structure,the concept of stress ratio is introduced,and the bar is divided into main components and secondary components based on the stress ratio,then by drawing the axial force of the main components,the force flow analysis of truss structures is realized.For rigid frame structure,ignoring the influence of torque and shear force,the influence of bending moment on structure is equivalent to axial force by using the principle of strain energy equivalence,and then the force flow analysis of rigid frame structure is realized by analyzing the equivalent axial force of main components.On this basis,based on the same concept of the ratio of the shortest force transmission path to the actual transmission force path,the evaluation method of transmission efficiency of truss structure and rigid frame structure is established.(3)The force flow analysis method is used to analyze the force flow and transmission efficiency of typical spatial single-layer reticulated shell structures and thin-shell structures respectively,and the main factors that affect the efficiency of structural transmission are discussed.Finally,a case study of power flow analysis shows the practicability and effectiveness of the force flow analysis method. |
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