# Optimization Method for Stiffened-Plate Layout in Box Structures Based on Load Paths
## 1 Introduction
Aiming at this kind of problem, [PERSON] et al. [15] proposed a method for the design of stiffener layouts in large box structures under moving load conditions based on multi-case topology optimization. They utilized the principle of equivalent force to partition the model into functional sections for dimension reduction and subsequently conducted multi-case topology optimization to obtain the stiffener layout. Some scholars have tried to use the structural bionics method to achieve the lightweight design of the box structure. [PERSON] and [PERSON] et al. [16; 17] designed the internal reinforcement plate layout of the structure based on the adaptive method of the natural branching system growth mechanism. They optimized the spindle box, column, and bed of the machine tool by combining them with the dynamic sensitivity analysis, and the simulation and experimental results showed that the overall structure of the machine tool has been greatly improved. [PERSON] et al. [12; 18], based on an adaptive growth method inspired by natural branching phenomena, initiated growth from a sowing line and gradually expanded based on design sensitivity. The optimal reinforcement layout is finally obtained with superior performance over the original machine. However, in the selection of biological prototypes and structural design, the design ideas are more subjective and lack a theoretical basis. Additionally, the layout adaptive computation based on the natural branching growth mechanism is relatively complex, leading to very high manufacturing costs, especially for large box structures subjected to moving loads. In order to solve the troubles caused by the above problems, the load path originating from the civil engineering field provides a new idea. The load path can be seen as the search for the optimal load-transferred skeleton of truss structures to evaluate the force-transferring performance and rationality of the structure. However, this concept cannot be directly applied to the design of solid mechanical structures. [PERSON] et al. [19] proposed a method of force transmission path extraction for force flow based on the principle of elastic mechanics equilibrium on this basis, which provides a basis for the analysis and evaluation of structures. It has been studied in structural design in recent years. [PERSON] et al. [20] considered that dynamic factors should not be neglected in analyzing the load-carryingcapacity of complex structural components and analyzed the load-carrying characteristics of engine cylinder heads using load path theory. [PERSON], [PERSON] et al. [21] used the load function method to obtain the load path of a plate-shell structure, providing crucial insights for the structural design of aerospace components. [PERSON] and [PERSON] et al. [22; 23; 24; 25] optimized and improved automobile rims and control arms based on the load path analysis method. They combined biomimetic design methods to guide the shape optimization of skeletal structures, resulting in significant improvements in both lightweighting and structural strength [26]. These studies effectively demonstrate that load paths can accurately reflect internal load flow within structures, and the arrangement of materials according to the load path can effectively enhance structural stiffness. In summary, based on the above issues and conclusions, this paper proposes an optimization method for the internal stiffener layout of large box structures guided by load path. Firstly, the box structure is decomposed into functional sections to achieve dimension reduction. Then, on the basis of the working condition analysis, the load path method is used to visualize the path of each functional section. Finally, the layout of the reinforcement plate on each section is determined based on the force flow distribution and path analysis. The remaining parts of this paper are outlined as follows. The optimization methodology proposed in this paper with specific details is given in Section 2.