Xiaohao Li

Bio: Xiaohao Li is an academic researcher from Northeastern University (China). The author has contributed to research in topics: Truss. The author has co-authored 1 publications.

Impact Resistance Analysis and Optimization of Variant Truss Beam Structure Based on Material Properties.

Abstract: In order to meet the increasing application requirements with regards to structural impact resistance in industries such as mining, construction, aerospace engineering, and disaster relief and mitigation, this paper designs a variant truss beam structure with a large shrinkage ratio and high impact resistance. Based on the principle of the curved trajectory of scissor mechanisms, this paper conducts a finite element simulation analysis of the impact load on the truss beam structure, a theoretical analysis of the impact response and a relevant prototype bench-top experiment, completing a full study on the impact resistance mechanism of the designed variant truss beam structure under the impact load. In the paper, the buffer effect of the external load impact on the variant truss beam structure is analyzed from the perspective of the energy change of elastic–plastic deformation. This paper proposes an optimization strategy for the variant truss beam structure with the energy absorption rate as the optimization index through extensive analysis of the parameter response surfaces. The strategy integrates analyses on the response characteristic analysis of various configuration materials to obtain an optimal combination of component parameters that ensures that the strength of the truss beam structure meets set requirements. The strategy provides a feasible method with which to verify the effectiveness and impact resistance of a variant truss structure design.

Investigation and Analysis of Stress and Deformation Monitoring of Long-Span Steel Roof Trusses

Abstract: Structural stress and deformation monitoring and analysis were carried out for the 54 m long-span steel roof truss. To ensure the safety of the construction process, the stress and deformation of the steel roof trusses were monitored throughout the construction process. The numerical modeling of the structures with six different working conditions was carried out, and the points with the most critical values of stress and deformation were found. This work provides a theoretical basis for field monitoring during and after construction. The results show that the maximum vertical displacement of a steel roof truss during all modeled working conditions and the maximum measured displacement are within the Chinese building code’s requirements. The maximum value of stress found during analysis of the structure during the construction process and the maximum measured stress are much less than the yield stress. The structural stress remains in the elastic range. The reasons for the differences between the calculated and measured results were analyzed.

Dynamics and Application of Modern, Smart, and Active Elements or Structures

Abstract: The Special Issue (SI) "Dynamics and Application of Modern, Smart, and Active Elements or Structures" is focused on covering all of the newest outcomes and trends in the nonlinear mechanics of systems and structures with smart, active, and modern materials [...].

Implementation of the Weak Link Problem for Trusses

Abstract: This article examines the application of the theory of critical strain energy levels to the determination of the limiting states of rod systems. A redundant truss is chosen to illustrate the peculiarities of changes in the self-stressing states of the structure at critical strain energy levels. The removal of ties when they reach their stress or strain limits leads to a change in the state of self-stress in the structure, which is illustrated by the removal of the rods in the trusses. The matrix notation of the governing equations for the structure allows us to visualize both the formulation of the problem and the course of its solution. We present the formulation and algorithm for solving the problem of a weak link in the structure by the example of a five-core redundant truss. The basic equations of matrix structural mechanics are given, allowing us to implement the algorithm and to determine the unknown parameters of the problem in the form of the method of displacements and the method of forces. The mathematical model of the problem is presented in the form of an eigenvalues problem, which allows us to investigate the extreme properties of the structure’s strain energy in the whole area of admissible parameter values, including the boundaries. The eigenvalues and eigenvectors make it possible to determine the extreme values of the nodal reactive forces of the structure or displacements, depending on the chosen formulation of the problem. The internal forces and deformations in the rods depend on the nodal vectors of external influences. The applied design load is balanced by the internal forces of the system and remains unchanged. This follows from the equality of the work of external forces to a part of the potential energy of the structure. The remaining part of the strain energy allows us to find the limit values of the reactive response of the structure to external actions. Additional actions on the structure can lead to the bearing capacity lost if they exceed the limits of the structure’s response. Examples show an algorithm for finding the weak link in a structure and identifying the rods that will be the first to fail under external loads. The matrices of stiffness and flexibility are formed, and the eigenvalues and vectors are found, which allow for the construction of the limit surface of allowable influences on the structure.

Design and Mechanical Characterisation of a Large Truss Structure for Continuous Manufacturing in Space

Abstract: In this paper, large space structures are essential components of significant equipment in orbits, such as megawatt-class solar power plants and long baseline interferometry. However, to realize the in-space fabrication of such megastructures, the primary consideration is the continuous fabrication of the structure. In this paper, we propose and design a structural form that differs from the minimum constituent unit shape of conventional truss structures by using an efficient winding and weaving method to construct truss structures. The continuously buildable one-dimensional truss’s structural design and mechanical properties are investigated. The parameters affecting the fundamental frequency of the truss structure are analyzed through modeling, simulation and experimental verification of the continuously buildable 1D truss. It is concluded that this configuration truss can be built continuously in space. The most influential factors on the fundamental truss frequency are the truss section spacing, the total truss length and the truss-specific stiffness. The simulated and theoretical values of the truss’s static stiffness and vibration frequency have minor errors, which provide a basis for the configuration design for the continuous manufacturing of large truss structures in space.