23 results about "Neutral axis" patented technology

The application discloses a pipeline connecting piece deflection experiment device, which comprises an experiment table and further comprises a movable mounting frame arranged above the experiment table and used for driving a distance measuring sensor to move and avoid the loading path of a lifting test head; the lifting test head is arranged above the movable mounting frame and used for testing and pushing the connecting piece and simultaneously driving the movable mounting frame to move; and the adjustable placing frame is arranged below the lifting test head and used for placing the connecting piece and simultaneously adjusting the placing height of the connecting piece. Through the cooperation of the adjustable placing frame, the distance measuring sensor and the control device, the distance measuring sensor can detect the initial distance on the upper surface of the connecting piece in real time, the control device can drive the second hydraulic rod according to the thickness judged according to the distance, the placing block can be lifted along the opening outer sleeve, and the neutral axis of the connecting piece and the loading axis of the test head can be accurately matched, so that the stress deviation problem caused by the fact that the traditional fixed support cannot be adapted to connecting pieces with different thicknesses is solved.

The invention belongs to the technical field of bridge steel structure design, and discloses a method and system for determining the arrangement positions of multiple longitudinal stiffening ribs of a steel bridge web, and the method comprises the steps that constraint of a steel top plate, a steel bottom plate and two transverse stiffening ribs on a mother plate is simply supported; dividing the stiffening plate into four-side simply supported sub-grids according to the longitudinal stiffening ribs, calculating bending and shearing buckling coefficients and obtaining critical buckling stress; a bending and buckling coefficient is expressed as a function of a clear distance between longitudinal stiffening ribs based on geometric similarity; and adopting a bending and shearing interaction buckling criterion, recursively solving the position of each longitudinal stiffening rib from a pressed edge, and carrying out constraint screening according to monotonically increasing distance, arrangement not crossing a neutral axis and the like. According to the method, reasonable arrangement can be directly output, and design consistency and efficiency are improved.

To specify a damage form and a damage place of a member level of a steel structure building, and to accurately monitor damage.SOLUTION: A strain detector is directly provided on a surface of a column and a beam of a multi-story steel structure building having a steel column and a steel beam, (1) First information on yield and local buckling of the column and (2) second information on buckling, cracking, breaking, and a neutral axis position in combination with a slab of the beam are obtained, a degree of damage of the steel column and beam is evaluated based on the first information and the second information, and determination on restoration is made based on the evaluation.SELECTED DRAWING: Figure 1

This invention discloses a method for strength calculation of a detachable support device. The method includes: obtaining the supporting force and radial force per unit length of the detachable support device; calculating the bending moment and horizontal tensile force at the connecting section based on the supporting force and the radial force per unit length; establishing the static moment equilibrium equation of the connecting section and determining the neutral axis position of the connecting section through iterative calculation; calculating the moment of inertia of the connecting section based on the neutral axis position; and calculating the maximum tensile stress borne by the fastener based on the moment of inertia, the bending moment, and the horizontal tensile force, so as to perform strength verification of the connecting section. This invention derives the strength verification formula and judgment criteria for key stress sections in detachable support structures, which is convenient for engineering technicians and ensures operational safety.

The invention provides a method for analyzing the optimal installation position and the vibration reduction effect of a gear damping ring, and the method comprises the steps: S1, carrying out the modal analysis of an initially designed unslotted spiral bevel gear shaft, and determining a dangerous vibration mode and the corresponding modal displacement; s2, damping ring design is carried out aiming at a dangerous vibration mode which cannot be avoided by frequency modulation, a position with large modal displacement is selected for slotting, and gear shaft strength checking is carried out; s3, a damping ring is installed in the slotted gear shaft, and modal analysis is conducted on the bevel gear shaft assembly; s4, the maximum radial displacement, the axial displacement and the neutral axis radius of the dangerous vibration mode at the damping groove position are obtained through analysis; s5, according to the damping ring vibration attenuation principle, drawing a curve graph of the resonance amplitude coefficient Q and the initial displacement, and evaluating the vibration attenuation effect; and S6, checking the strength of the damping ring. According to the invention, timeliness and economical efficiency of gear shaft damping ring design are taken into consideration, and structure adjustment is completed before a test, so that engineering cost is saved.

The application provides a packaging structure based on secondary Bessel function simple branch modulation, an anti-vibration fiber laser and a packaging method, and belongs to the technical field of fiber laser packaging. The packaging structure comprises a metal base, the metal base is provided with a groove, the groove is provided with a fiber grating area near the neutral axis of the bottom of the groove, the bottom of the groove is provided with a convex structure, the shape of the convex structure is an asymmetric arc shape, and the curve of the arc shape is generated by a secondary Bessel curve. The groove is provided with a fiber, and the two ends of the fiber are fixed on the bottom of the groove. The fiber remains in a relaxed state in the middle segment area of the groove. A gap is left around the middle segment of the groove, or low modulus material is filled in the gap. The application effectively improves the lateral equivalent stiffness, multi-step improves the structure natural frequency in multiple directions, and further improves the overall first-order natural frequency, so that excellent frequency noise suppression capability is shown in the vibration test, and the stability of the fiber laser under acceleration disturbance is greatly improved.

The invention relates to the technical field of support-free calculation, in particular to a 4D steel fiber concrete thin laminated slab support-free calculation method, which comprises the following steps of: acquiring structural parameters and material parameters of a laminated slab, calculating a neutral axis position and converting a cross-sectional inertia moment; based on the characteristic value of the steel fiber content and the influence coefficient of the steel fiber content on the axis tensile strength, the concrete axis tensile strength is corrected, and the cracking bending moment is calculated; respectively calculating the contribution of a truss web member to the equivalent flexural rigidity according to a truss binding mode; combining the influence coefficient of the steel fiber on the short-term rigidity of the flexural member and the contribution value to obtain the short-term rigidity before cracking; and the cracking bending moment and the short-term rigidity are compared with the corresponding threshold values respectively, and if the requirements are met, it is judged that support-free construction of the laminated slab can be achieved. According to the method, whether the laminated slab can be constructed without support or not is accurately judged.

The present application relates to a tunnel lining external load inversion method and system based on a physical information neural network, obtaining monitoring data of the inner surface of the tunnel lining to be inverted; according to curved beam theory, establishing a control equation of external load and lining neutral axis deformation, and determining boundary conditions; according to the theory of material mechanics, establishing the corresponding relationship between the strain and displacement of the inner surface of the lining and the strain and displacement of the neutral axis position; constructing a physical information neural network, taking the spatial coordinates of the lining as the input of the physical information neural network, and taking the normal displacement, tangential displacement of the neutral axis at different coordinates and the external load of the lining as the output, and converting the neutral axis displacement into the strain and displacement of the inner surface of the lining; through training of the physical information neural network, the input-output relationship satisfies the control equation of the external load and the lining deformation, the boundary conditions and the monitoring data, and the normal displacement, tangential displacement of the neutral axis at the corresponding coordinates and the external load of the lining are obtained, which are the inversion results.

The present application relates to a kind of prestressed steel wood combination node stress performance analysis method and device, method includes the following steps: S1, the key parameter of prestressed steel wood combination node is obtained;S2, based on the direct balance method of beam-column interface and key parameter, wood beam stress balance equation is established, wood beam stress balance equation is solved, the control function of beam end neutral axis height is obtained, control function is the function about beam-column interface opening angle;S3, the parameter of control function of beam end neutral axis height is changed, and the different critical angle in the opening angle change process of beam-column interface is obtained by calculation;S4, based on the control function of beam end neutral axis height, critical angle and node bending moment, bending moment-angle curve is obtained.Compared with prior art, the present application has the advantages of accurate and fast analysis.

The invention discloses an anti-eccentric loading tool device for an axial loading test of a stiffened plate. The device belongs to the technical field of ship and ocean engineering structure tests and is composed of a stiffened plate test piece, a steel head assembly, an end loading clamp, a side clamp and a supporting base. The steel head is welded to the end of the stiffened plate according to the neutralizing shaft, the loading clamp is adopted for clamping, it is ensured that loading force acts along the neutralizing shaft of the stiffened plate, and end face bending moment is avoided; meanwhile, adjustable clamps are arranged on the two sides of the stiffened plate, flexible adjustment and clamping are conducted according to the position of the test piece, accurate simulation of the four-side simple support boundary conditions is achieved, and the loading precision and the test reliability are improved; according to the invention, high-precision loading path control and real boundary condition reproduction are realized through a fixed loading end, centering steel head welding, an adjustable side clamp and a rigid base; the device can prevent loading eccentricity, eliminate end face bending moment and improve loading precision and repeatability; and meanwhile, the device is suitable for buckling and ultimate bearing capacity tests of different types of stiffened plates.

The application provides a kind of fatigue life prediction method and system based on improved CHM RC beam, it is related to RC beam fatigue life prediction technical field, specific steps include: crack hinge model is built, RC beam is split into virtual crack hinge in midspan and two sides elastomer, section parameter and beam body basic parameter are collected, the bending moment of stress component axial force and each axial force to neutral axis is calculated;Set cycle block division rule, calculate strain and axial force increment, record the cycle number under current cycle block and obtain the balance error value;Optimize section parameter with genetic algorithm to get optimal combination;Calculate cumulative damage value, compare with threshold value to determine failure, if failure, add cycle number to get life.The application accurately distinguishes the damage difference of different stress amplitudes under the same deflection, provides reliable basis at mechanics level for life prediction, truly restores the evolution chain of crack propagation to stress redistribution and then to damage acceleration, makes the model highly match with the real damage process of RC beam.

The invention discloses a concrete box girder nonlinear damage identification method considering a shear hysteresis effect, and the method comprises the steps: estimating the position of a neutral axis of a box girder through long gauge length strain and material performance, and then determining the curvature distribution, bending rigidity and deflection. A simulation result shows that the evaluation parameter (bending rigidity) can clearly and quantitatively reflect the degradation process of the box girder. Meanwhile, the long gauge length strain can reflect global response and can also capture local changes, and the structural response obtained through inversion is highly consistent with the actual measurement result. Compared with a finite element model correction method, the method does not need a finite element model, and can consider nonlinear and shear hysteresis effects; meanwhile, the method is suitable for the whole process of structure failure.

The invention discloses a wind power blade buckling test vector bending moment calculation method and device based on a neutral axis, and relates to the field of wind power blade component testing. The method comprises the following steps: completing coordinate conversion from a full-size blade to a blade section according to a neutral axis, an elastic axis and an elastic axis coordinate system of the full-size blade; calculating the strain value of the blade section through the structural characteristics of the blade section and the coordinate conversion bending moment variable; calculating to obtain a neutral axis and an inclination angle according to the strain value of the blade section, and generating a trailing edge section section; calculating the position of a load shaft of the trailing edge section, further calculating the strain and vector force of a specific position, and finally obtaining the vector bending moment of the trailing edge section. The device comprises a steel structure tool, a vector bending moment loading device and an electrical control system. The loading device controls the loading direction of a loading oil cylinder through four small electric cylinders, and application of the vector bending moment is achieved. According to the method, the full-size test is mapped through the part-level test of the trailing edge section, and the vector bending moment borne by the trailing edge section is analyzed, so that the load matching degree of the blade test and the real stress working condition is improved.

This invention relates to a test method for determining the direct tensile strength of concrete based on a tension-compression bar model. The method includes the following steps: preparing a concrete beam specimen, wherein the concrete beam specimen is constructed with a stepped opening at mid-span, and tension and compression bars are sequentially arranged from bottom to top within the stepped opening; applying pressure to the stepped opening of the concrete beam specimen until the specimen fails, and recording the pressure load; determining the mid-span bending moment of the concrete beam specimen based on the pressure load; and determining the direct tensile strength of the concrete based on the elastic modulus, neutral axis height, moment of inertia of the concrete beam specimen, and a predetermined tension-compression bar model. This invention has the advantages of enabling the specimen to operate under approximately uniform tensile stress, producing test results close to the direct tensile strength, and being simple to operate.

This invention relates to the field of tunnel and underground engineering design technology, specifically to a method for identifying weak areas in tunnels and providing differentiated support based on asymmetric load evolution. The method involves collecting pressure distribution and deformation data of the tunnel cross-section and constructing a continuous arc-length coordinate system along the neutral axis of the support structure. Based on the data and coordinate system, the geometric, stress, and energy states of the tunnel cross-section are analyzed to obtain geometric deformation analysis results, eccentricity evaluation results, and toughness judgment results at any point on the support section. A multi-index collaborative judgment model is constructed based on the above multi-dimensional index results to generate a weighted index distribution map of the tunnel cross-section's weakness. Based on the multi-dimensional results and the index distribution map, differentiated support decisions for the tunnel are designed. This invention identifies weak areas in tunnel support based on multi-dimensional physical indicators of deformation, stress, and energy, and conducts asymmetric differentiated support parameter decisions, realizing the transformation from traditional equal-strength design to asymmetric targeted support, thereby enhancing the stability and safety of the eccentrically loaded side structure.

The application discloses a computer mechanical analysis method for single-side bolt connection joint of fabricated component, which comprises the following steps: 1, inputting parameters in the computer; 2, judging the joint bending moment M and joint axial force N, and initially calculating the height x of the outer edge of the compression zone to the neutral axis, the joint section rotation angle θ, the bolt tension T and the outer edge stress σ0 of the compression zone of the component; if the joint axial force N is a compression force, the initial calculation result is output; 4, under the condition that N is a compression force, comparing x and h, if x < h and T > 0 are obtained through the initial calculation, the initial calculation result is correct, and the initial calculation result is output; if not, x, θ, T and / or σ0 are modified; 5, outputting the modified data. The application can quickly and effectively analyze the stress state of the connection joint and the bolt through the computer, can liberate the designers from the mechanical checking calculation and further improves the design efficiency.

The invention discloses a box type hull structure and a design method, and the box type hull structure comprises a cabin body which extends in the longitudinal direction and is provided with an inner cabin; the first reinforcing plate is arranged in the inner cabin and extends in the longitudinal direction; the second reinforcing plate is arranged in the inner cabin and extends in the longitudinal direction, the second reinforcing plate and the first reinforcing plate are spaced in the transverse direction, and the second reinforcing plate and the first reinforcing plate are symmetrically arranged along the middle longitudinal section of the cabin body; the first reinforcing plate and the second reinforcing plate divide the inner cabin into a left cabin, a middle cabin and a right cabin which are sequentially arranged in the transverse direction. The neutral axis of the cross section structure of the cabin body is located at the geometric midline position of the cross section structure of the cabin body in the height direction. The first reinforcing plate and the second reinforcing plate are symmetrically arranged along the middle longitudinal section at intervals, and the structure neutralizing shaft of the cross section of the ship body structure is located at the geometric center line position of the cross section structure in the height direction, so that under the condition that the same bearing requirement is met, the using amount of structural materials can be remarkably reduced, the ship body is lightened, and the construction cost is effectively reduced.

The invention discloses a method for analyzing the bending performance of a steel-concrete sandwich panel based on strain monitoring, and relates to the technical field of structural performance evaluation, and the method comprises the following steps: S1, collecting cross section distributed strain data, and reconstructing a continuous strain field along the height direction of a cross section based on a spatial interpolation algorithm; based on the continuous strain field, dynamically tracking the position of a neutral shaft, and performing staged calculation to obtain a macroscopic bending moment-curvature relation and full-field deflection distribution; and S2, based on the continuous strain field, extracting strain data of paired sensors at the steel-concrete interface. According to the method for analyzing the bending performance of the steel-mixed-steel sandwich panel, the stress state of the cross section is finely described by reconstructing the continuous strain field, deviation caused by traditional discrete point monitoring and fixed assumption is overcome, and therefore the response process of the structure under the load effect is more truly reflected, and the bending performance of the steel-mixed-steel sandwich panel is improved. The dynamic quantitative evaluation of the steel and concrete bond slip behavior is realized.

The invention belongs to the technical field of structural safety detection, and discloses a concrete box girder bridge section stiffness distribution updating method which comprises the following steps: (1) acquiring strain data required for updating the section stiffness of a box girder; (2) establishing a stress-strain analysis theory; (3) discretizing the cross section of the box girder to establish a numerical model; and (4) updating the rigidity distribution of the cross section of the box girder. Based on the problems that the rigidity distribution of the cross section of the box girder bridge is uneven and the stress-strain distribution of the cross section is complex, a generalized girder theory and a model updating method are used for inverting the rigidity distribution condition in the cross section of the box girder, and the stress-strain in the cross section of the box girder when the rigidity is uneven is accurately calculated. According to the method, a rigidity updating strategy taking the inertia moment and the neutral axis as constraint conditions is applied, the section rigidity distribution can be well updated, and the rigidity updating calculation efficiency is improved. Meanwhile, the method considers the special deformation mode of the cross section of the box girder, obtains the proportion of various deformation modes in the total stress, and is more beneficial to the evaluation of the stress condition.

The invention provides an offshore wind turbine tower deformation monitoring method, and belongs to the technical field of ocean engineering structure monitoring based on computer data processing. Strain sensors are pasted at specific positions of the inner surface of the segmented tower drum structure to collect data, so that the influence of a severe external environment on the sensors is avoided. Different from an iFEM requiring a large number of measuring points, the method utilizes sparse discrete strain data, converts discrete strain into discrete curvature in combination with the distance between the measuring points and a neutral axis, and generates a continuous curvature function through interpolation, thereby solving the problems that a DST matrix is difficult to construct in a traditional modal method and accumulative errors are large in a Ko displacement theory. And finally, through a curvature displacement inversion method and recursive splicing, deducing an overall outer surface deformation curve of the segmented tower drum structure. According to the invention, the number of required sensors and the layout complexity are reduced, and the dependence of a non-contact method on the environment and the limitation of a modal method and a Ko displacement theory on the segmented variable cross-section tower drum are overcome.

The invention discloses a wind power blade sandwich structure variable cross-section section shear strength calculation method, which comprises the following steps: step 1, determining the chordwise position and length of a wind power blade sandwich structure variable cross-section section, and selecting a plurality of chordwise cross sections from the determined wind power blade sandwich structure variable cross-section section; step 2, determining a neutral axis position of each chordwise section and a material layer attribute at the neutral axis position; step 3, calculating an equivalent inertia moment of each chordwise section about a neutral axis of the chordwise section; step 4, calculating shear stress at a neutral axis in each chordwise section; 5, calculating the shear stress at the centroid position of each material layer in each chordwise section; and step 6, checking the shear strength. According to the invention, the intensity distribution can be rapidly analyzed, and the damage form can be identified. In addition, the position of the neutral axis of the variable cross-section section of the wind power blade sandwich structure is automatically and accurately calculated based on the whale optimization algorithm, and then high-precision shear strength checking is completed.

The invention discloses a concrete box girder non-linear deflection identification method considering a shear hysteresis effect, and the method comprises the steps: estimating the position of a neutral axis of a box girder through long gauge length strain and material performance, and then determining the curvature distribution and bending deflection; meanwhile, the shear hysteresis effect is considered, the additional deflection is calculated, and finally the corrected deflection after the pure bending deformation and the shear hysteresis effect are considered is obtained. By means of the method, the deformation state of the box girder structure can be accurately recognized in different load stages, and good adaptability is still achieved after concrete cracks. According to the method, the shearing force hysteresis effect and the material nonlinear characteristics are considered at the same time, limitation of traditional plane section assumption is avoided, and the deflection recognition accuracy is remarkably improved. Meanwhile, additional reference points do not need to be arranged, deflection identification can be achieved only by depending on strain monitoring data, and application and popularization in a bridge health monitoring system are facilitated.

The application provides a kind of offshore wind turbine tower deformation monitoring method, belong to the ocean engineering structure monitoring technical field based on computer data processing;Through the data collection of strain sensor pasted in the specific position of the inner surface of segmented tower structure, avoid the influence of sensor by bad external environment.Different from iFEM which needs a large number of measuring points, this method uses sparse discrete strain data, combines the distance between measuring points and neutral axis to convert discrete strain into discrete curvature, and then generates continuous curvature function through interpolation, which solves the problem of difficult construction of DST matrix in traditional modal method and large cumulative error in Ko displacement theory.Finally, through curvature displacement inversion method and recursive splicing, the overall outer surface deformation curve of segmented tower structure is derived.The application not only reduces the number of sensors required and the complexity of layout, but also overcomes the dependence of non-contact method on environment and the limitations of modal method and Ko displacement theory on segmented variable cross-section tower.