11 results about "Shell theory" patented technology

The invention provides a method for evaluating the stability of an inner steel pipe of a round hollow interlayer steel pipe concrete member, and relates to the technical field of constructional engineering. An inner steel pipe buckling model of the concrete member is established through mechanical analysis of the concrete member; sandwich concrete can be regarded as an elastic foundation, an inner steel pipe is a thin-wall structure on the foundation for mechanical analysis, and compression resistance and tensile elastic foundation bed coefficients of the interlayer concrete regarded as the elastic foundation are deduced and simplified; introducing a bending wavelength calculation formula of the werkel elastic foundation long beam to calculate the bending wavelength of the inner steel pipe; and based on the thin-shell theory, a critical stress expression of the inner steel pipe is solved by utilizing an energy method. Therefore, the critical stress value of local buckling instability of the inner steel pipe in the circular hollow interlayer steel pipe concrete member can be determined, the stability of the inner steel pipe is evaluated, local instability of the inner steel pipe is prevented, the good mechanical property of the whole member is guaranteed, and design guidance is provided for engineering practice.

The present application relates to a kind of large section deep soft rock tunnel combined support system and construction method, the present application is combined with elastic shell theory and equivalent section method, a steel arch frame-grating combined support mode suitable for deep large section soft rock tunnel is proposed, the support rigidity of simply using steel arch frame or grid steel frame is overcome or supported, the disadvantage of lower in long-term large deformation unfavorable surrounding rock stability and deformation control, solve the problem that the stress of existing support structure is larger, the self-bearing capacity of surrounding rock cannot be fully exerted, cause material waste is serious, the safety factor of support structure is low, difficult to guarantee the stability of tunnel, and provide a simple and practical construction method for tunnel excavation and support.

The application discloses a rotating wing type variable cross-section crack blade fault characterization and dynamics analysis method, belongs to the field of rotating wing type variable cross-section crack blade fault characterization and dynamics analysis, and comprises the following steps: according to the finite element theory and the plate shell theory, based on centrifugal rigidification, rotation softening and the coriolis force effect, a motion differential equation of the wing type variable cross-section blade is established; according to the motion differential equation of the wing type variable cross-section blade, based on the crack existing in the blade, the breathing effect between crack surfaces is equivalent by adopting a spring unit, a rotating wing type variable cross-section crack blade dynamics model containing the breathing effect is established, vibration energy theory is adopted to convert the displacement response into energy response, based on the rotating crack blade crack diagnosis index with the breathing effect, the crack characteristics of the blade are obtained, and the application is more effective and accurate in analyzing the rotating crack blade fault, and can provide theoretical guidance for detection and diagnosis of the rotating crack blade.

This invention relates to a method for analyzing the turning stability of a truncated cone thin-walled structure, belonging to the field of machining technology. First, based on shell theory, a vibration differential equation considering the rotational effects of centrifugal force, Coriolis force, and initial ring tension is established. The cantilever-free boundary condition expression is substituted into the equation, and the natural frequencies and modal parameters of the rotating truncated cone thin-walled structure are obtained by solving the equation using a generalized differential quadrature method. Then, considering the vibration of the tool along the generatrix of the shell and the vibration of the workpiece perpendicular to the generatrix, a flexible workpiece-tool coupled turning dynamics model is established. This model simultaneously considers the influence of shell rotation and multi-mode vibration, achieving a more accurate prediction of the turning process of the truncated cone thin-walled structure.

The invention provides an underwater ribbed cylindrical shell sound radiation prediction method and system based on parametric modeling, and the method comprises the following steps: (1) constructing a parametric shell model, and determining geometric parameters, material parameters, rib parameters and fluid parameters; (2) establishing a vibration control equation on the basis of a Donnell-Mushtari shell theory; (3) solving a frequency domain vibration response by adopting a modal superposition method, and calculating a modal amplitude; (4) calculating a sound radiation field based on a Helmholtz integral equation, acquiring near-field sound pressure through numerical integration, and acquiring far-field sound pressure by adopting a modal expansion method; and (5) changing the shell thickness and the excitation amplitude ratio F2 / F1 by optimizing structural parameters and excitation configuration, and observing and analyzing the distribution condition of near-distance radiation noise and the amplitude change condition of a main peak of a long-distance radiation noise level frequency response curve. The calculation method is simple, the real-time analysis effect is good, and technical support can be provided for vibration radiation noise analysis and low-noise structure design of an underwater operation platform and a pipeline structure.

The invention provides a composite material plate shell multi-scale simulation method based on clustering order reduction, and belongs to the technical field of composite material multi-scale computational mechanics, and the method comprises the steps: building a voxelization 3D model and an associated 2D plate shell discrete model; constructing a single Lippmann-Schwinger control equation on the basis of a plate-shell theory and a periodic boundary, solving a macroscopic equivalent resultant force / bending moment of the single Lippmann-Schwinger control equation by adopting FFT (Fast Fourier Transform), and grouping discrete points through a clustering algorithm to realize order reduction; the method comprises the following steps of: clustering a plurality of plate shell models, disassembling an original equation into a cluster-level discrete equation based on a clustering result, constructing a constitutive updating scheme based on a 3D model, solving the model based on a Newton-Raphson iteration scheme, and distributing a cluster result to pixels of the plate shell model according to a solving result to obtain a mechanical response of the model. According to the method, the theoretical model is established through physical reasonable hypothesis; effective unit condensation of a real 3D model is realized by constructing a voxelization-based finite prism discrete scheme; and the elastoplasticity and damage failure analysis of the composite material is realized by constructing a 2D plan-3D solid model alternate solution scheme.

This invention discloses a calculation method for the shear failure classification of tunnel initial support structures, including: establishing a mechanical model of the tunnel initial support structure based on thin-shell theory, and obtaining the deflection expression to derive the internal force expression; analyzing the influence of the strength parameters and structural parameters of the initial support structure on the internal forces; analyzing the internal force distribution law of the initial support structure at different cross-sections; based on the analysis results, establishing a shear failure criterion for the initial support structure based on the Mohr-Coulomb strength criterion and the static equilibrium condition at any point of the initial support shell structure; proposing the concept of initial support structure failure classification; a method for selecting support parameters based on the failure threshold; and using C language to develop a shear program for the failure of any micro-element inside the shell, realizing a visual display of the failure area and failure ratio of the initial support structure, and revealing the mechanism of shear failure of the initial support structure. This invention solves the problem of quantitatively analyzing the overall stability of tunnel initial support structures from a mechanical perspective and establishing a reasonable and objective strength criterion.

The invention discloses a method for analyzing the dynamic response of a sandwich composite structure under blast shock. First, a blast shock model of a sandwich composite structure with multiple types of pores and various elastic substrate reinforcements is constructed. Then, based on the classical plate and shell theory, the sandwich composite structure models with different forms of elastic substrates are described. Subsequently, linear discretization is performed in the spatial and temporal domains respectively, and the iterative method is used to solve the problem. The invention discloses a method for analyzing the dynamic response of a sandwich composite structure under blast shock, which can accurately characterize the influence of material property parameters, structural geometric parameters, forms and action positions of multi-point blast shock loads, pore distribution types, types of elastic substrates and compensation capabilities on the dynamic response of a porous and elastic substrate FGM sandwich hyperbolic plate under multi-point blast shock in a thermal environment.

The invention discloses a high-precision Cosseerat model and method based on a coarsened shell. The high-precision Cosseerat model and method are used for solving the problem that an existing Cosseerat model is difficult to carry out high-simulation-precision elastic simulation on a heterogeneous material mixed cable. According to the model, a Cosseerat theory is adopted to carry out modeling on a slender cable, a Kirchhoff-Love shell theory is adopted to carry out modeling on cross section energy of the cable, and a material perception shape function is constructed to carry out numerical coarsening so as to reduce the degree of freedom; meanwhile, a multi-constraint condition module is introduced, and multiple constraint types such as fixed constraint, hinge constraint and sliding constraint are supported. The model combines the advantages of a Cosserat model and a Kirchhoff-Love shell theory, the calculation efficiency is improved through numerical coarsening, complex working conditions are accurately simulated through multiple constraint conditions, the simulation efficiency is improved with less freedom compared with a direct finite element method (FEM), the simulation precision is improved through a material perception energy function and the multiple constraint conditions compared with a traditional Cosserat model, and the simulation efficiency is improved. Local and global deformation of the hybrid cable under complex constraints can be calculated more accurately, and the method has important application value in the field of high-precision simulation of heterogeneous material hybrid cables.

The application discloses a kind of steel plate internal damage detection method based on guided wave and PINNs, the method includes the following steps, first, establish plane rectangular coordinate system, guided wave is applied to the surface of steel plate and guided wave receiving point is selected, guided wave is applied to the steel plate, select M time points of free vibration of the steel plate, and calculate the out-of-plane displacement of the steel plate at all guided wave receiving points, PINNs model and DNN model are constructed, PINNs model and DNN model are trained simultaneously using the out-of-plane displacement of the steel plate at all guided wave receiving points, coordinates and time, the steel plate is detected using PINNs model and DNN model, and the position of the steel plate damage is located.The application solves wave equation by physical information neural network, avoids complex finite difference method formula, thereby reduces the cost of calculation, and the physical equation based on plate shell theory is simpler than three-dimensional wave equation, reduces the cost of calculation, and improves the accuracy of internal damage positioning of the steel plate, and the internal damage position of the steel plate can be located.

The application discloses a lofted curved surface shell structure optimization design method based on mixed sensitivity. The method takes the offset amount of the initial section curve control vertex coordinates as the design variable, sorts the section curve, unifies the parameter direction, inserts nodes and the like, and generates an initial lofted curved surface through lofting. The initial lofted curved surface is refined, and a refined lofted curved surface model for structure analysis is constructed. Structural response analysis is carried out based on the equal geometry Reissner-Mindlin shell theory. The derivative of the objective function to the design variable is decomposed into the accompanying analytical sensitivity term and the finite difference sensitivity term. Under the geometric constraint, the minimum flexibility is taken as the optimization target for iteration, and the optimized section curve, the lofted curved surface and the corresponding structural response are output. The application can retain the design intention driven by the section characteristic curve, reduce the design space dimension, improve the realizability of the sensitivity analysis and the optimization efficiency, and realize the high-quality and efficient optimization design of the shell structure.