89 results about "Neutral axis" patented technology

The invention relates to the technical field of construction and the technical field of software, and discloses a fabricated structure evaluation method and device based on a toughness value and carbon emission, and the method comprises the steps: adding the damage volumes of all interfaces, and obtaining the damage amount of a fabricated structure; when the damage amount of the fabricated structure is within the damage range, a repair scheme of the fabricated structure is obtained, and the carbon emission amount of the repair scheme is generated; according to the length of each interface, the inertia moment of the complete part of each interface, the moving distance of the neutral axis of each interface and the contact surface rigidity model, the contact surface rigidity of the fabricated structure is generated, and according to the contact surface rigidity of the fabricated structure, the material elasticity modulus of the fabricated structure and the toughness model, the toughness value of the fabricated structure is generated. And performing specific value calculation on the carbon emission of the repair scheme and the toughness value of the fabricated structure to generate an evaluation value of the repair scheme. According to the invention, the evaluation efficiency of the repair scheme of the fabricated structure can be improved.

The invention relates to a tunnel lining external load inversion method and system based on a physical information neural network. The method comprises the following steps: acquiring monitoring data of the inner surface of a to-be-inverted tunnel lining; according to the curved beam theory, a control equation of external load and lining neutral axis deformation is established, and boundary conditions are determined; according to the material mechanics theory, the corresponding relation between the strain and displacement of the inner side surface of the lining and the strain and displacement of the neutral axis position is established; a physical information neural network is constructed, lining space coordinates serve as input of the physical information neural network, neutral axis normal displacement, tangential displacement and lining external load at different coordinates serve as output, and neutral axis displacement is converted into lining inner surface strain and displacement; the physical information neural network is trained, so that the input and output relation meets the control equation, boundary conditions and monitoring data of the external load and lining deformation, and the normal displacement, tangential displacement and lining external load of the neutral axis at the corresponding coordinates are obtained, namely, the inversion result is obtained.

The invention provides a method for calculating a flexural capacity characteristic value of a steel and UHPC (Ultra High Performance Concrete) composite structural beam. Different constitutive models are adopted according to performance characteristics of UHPC, a T-shaped steel beam and a steel bar in the composite structural beam, and the contribution of material strain hardening performance to the flexural capacity is fully considered; compared with an ideal elastic-plastic model, the real performance of the structure can be better obtained; meanwhile, the cross section curvature, the curvature iterative calculation increment and the neutral axis position iterative calculation increment are given for initial values of conventional bridge calculation, and the neutral axis position and the cross section curvature are searched by adopting an influence coefficient method, so that the search speed is increased, and the problem that convergence cannot be realized due to manual setting of the iterative increment is solved; and finally, the condition that the UHPC top strain reaches the UHPC compression limit strain or the T-shaped steel beam bottom strain reaches the steel limit strain is taken as a judgment condition, and two damage modes of UHPC crushing and the condition that the steel reaches the tensile ultimate strength can be considered at the same time.

The invention discloses a compression test clamping tool, system and method for a variable-thickness beveled laminated plate composite material, and relates to the technical field of aviation composite material mechanical property testing. The first long chuck and the second long chuck are respectively mounted on a variable-thickness side and an equal-thickness side of the beveled laminated plate sample, and the first long chuck mounted on the variable-thickness side is gradually thickened on a conical beveled layer and a thin section of the beveled laminated plate sample. According to the invention, the additional bending moment caused by eccentricity of a neutral shaft is effectively inhibited through the gradually-changed thickening design of the variable-thickness side long chuck in cooperation with gap control, and active inhibition of buckling instability of a beveling area is realized in combination with rigid fixation and surface roughening treatment of the short chuck; the method has the advantages that buckling instability is restrained, a failure area is accurately positioned, and samples of different configurations are adapted.

The invention discloses a method and system for calculating the longitudinal torsional rigidity effective rate of a rectangular pipe-jacking tunnel under combined acting force and a storage medium. The method comprises the following steps that S1, the bending-pressing-twisting combined acting force on a calculation unit of the rectangular pipe-jacking tunnel is obtained according to the stress condition of the rectangular pipe-jacking tunnel; s2, the stress state of the pipe jacking lining structure is judged according to the relation between the bending moment and the axial force, and the stress state of the structure is divided into two different conditions according to the position of a neutral axis; s3, for different stress states, according to deformation coordination conditions and mechanical equilibrium conditions, calculating the distance between a neutral axle on the section and the center of the section; s4, according to the torque balance condition and further according to the two different conditions, the position of the torsion center and the anti-friction torque generated by the concrete in the pressed area are calculated; and S5, calculating a joint torsion angle and equivalent torsional rigidity, and further calculating the effective rate of the torsional rigidity. The longitudinal torsional rigidity effective rate of the rectangular pipe-jacking tunnel under the bending, pressing and twisting combined acting force can be rapidly and accurately obtained, and a basis is provided for structural safety analysis of the rectangular pipe-jacking tunnel.

The invention discloses a composite beam capable of enhancing the ultimate strength of an ultimate concrete structure. The span of the beam is measured, a bending moment graph of the beam is drawn, according to analysis of the bending moment graph, UHPC is selected for a pure bending section (the middle of the span) above a neutral axis of the beam, the upper half part of the beam is covered, and common concrete is used for the rest parts; half of the beam height is selected to use UHPC on the upper portion, and the structural ultimate strength of the composite beam can be improved; the FRP rib is used on the lower portion of the beam, the tensile property and ductility of the lower portion can be improved, a sleeve grouting anchorage device (the inner wall of a metal sleeve is provided with threads) and a wedge-shaped anchorage device (the clamping section is wrapped with a copper sleeve) are adopted, the anchoring reliability is ensured through the double effects of chemical bonding and mechanical meshing, and due to the fact that the FRP rib can be subjected to brittle failure and is preset to be in a super rib failure mode, the tensile strength and ductility of the lower portion can be improved. The problem of brittle failure of the FRP rib is solved. The beam is simple in design, convenient to construct, reasonable in stress, high in structural ultimate strength, high in reliability, wide in application range and material-saving.

The invention relates to a method for verifying the positioning of a fibrous preform in a blade, the blade having been obtained by injecting a resin into a mould having the shape of a blade and in which a preform has been placed, the blade extending in an orthonormal blade frame of reference X, Y, Z, the blade comprising a blade root extending longitudinally along an axis X, a vane extending from the blade root along an axis Z, the blade having a thickness defined along an axis Y, the preform comprising glass tracers positioned at the surface of the preform, the centre of the tracers defining a neutral axis located at a height along the axis Z in the direction defined by the axis X, the method comprising the following steps: the acquisition (E31) of tomographic 2D projections of the blade using an imaging system comprising an X-ray source, each projection being acquired at a given orientation of the X-ray source with respect to the blade; the combining (E32, E32a, E32b) of the 2D projections in the direction of the axis Y so as to obtain a cumulative 2D image in the directions X and Z; the determining (E33), for each pixel column defined in the direction of the axis Z, of a greyscale profile; the processing (E34) of each of the profiles obtained so as to locate the position, in Z, of the neutral axis in the direction of the axis X.

The invention provides an improved CHM-based RC beam fatigue life prediction method and system, and relates to the technical field of RC beam fatigue life prediction, and the method comprises the specific steps: constructing a crack hinge model, splitting an RC beam into a midspan virtual crack hinge and elastic bodies at two sides, collecting section parameters and beam body basic parameters, and carrying out the construction of a crack hinge model; calculating the axial force of the stress component and the bending moment of each axial force to the neutral axis; setting a cycle block division rule, calculating strain and axial force increments, recording cycle times under the current cycle block, and obtaining a balance error value; using a genetic algorithm to optimize section parameters to obtain an optimal combination; and calculating an accumulated damage value, comparing the accumulated damage value with a threshold to judge failure, and if failure, accumulating cycle times to obtain the life. According to the method, the damage difference of different stress amplitudes under the same deflection is accurately distinguished, a reliable basis of a mechanical level is provided for life prediction, an evolution chain from crack propagation to stress redistribution to damage acceleration is truly restored, and the model is highly matched with the true damage process of the RC beam.

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.

The invention discloses a method and system for calculating the longitudinal torsional rigidity effective rate of a rectangular shield tunnel under combined acting force and a storage medium. The method comprises the following steps that S1, the bending-pressing-twisting combined acting force on a calculation unit of the rectangular shield tunnel is obtained according to the stress condition of the rectangular shield tunnel; s2, the stress state of the shield lining structure is judged according to the relation between the bending moment and the axial force, and the stress state of the structure is divided into two different conditions according to the position of the neutral axis; s3, for different stress states, according to deformation coordination conditions and mechanical equilibrium conditions, calculating the distance between a neutral axle on the section and the center of the section; s4, according to the torque balance condition and further according to the two different conditions, the position of the torsion center and the anti-friction torque generated by the concrete in the pressed area are calculated; and S5, calculating a joint torsion angle and equivalent torsional rigidity, and further calculating the effective rate of the torsional rigidity. According to the method, the longitudinal torsional rigidity effective rate of the rectangular shield tunnel under the bending, pressing and twisting combined acting force can be quickly and accurately obtained, and a basis is provided for structural safety analysis of the rectangular shield tunnel.

The invention discloses an arch bridge arch rib erection construction deflection monitoring method, which comprises the following steps that S1, an arch bridge arch rib is spliced, the arch bridge arch rib comprises two upper chords and two lower chords which are respectively distributed up and down, the upper chords and the lower chords are respectively provided with a plurality of distributed strain optical fibers, and two adjacent distributed strain optical fibers are connected to form a plurality of distributed strain optical fibers; connecting all the distributed strain optical fibers to form a path; s2, acquiring strain and temperature data of the distributed optical fiber online in real time; s3, temperature compensation axial strain and neutral axis axial strain are obtained through calculation according to the collected strain and temperature data, and the deflection of the arch rib is obtained through calculation. According to the method, the deflection of the arch rib in the erection construction stage can be monitored in real time, construction does not need to be interrupted, and the method can be applied to the whole construction process; multiple parameters such as deflection, strain and temperature can be measured at the same time; the system can run and cover full life cycle monitoring of the arch rib, and can be converted into structure health monitoring after construction is completed.

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.

To provide a calculation device and the like capable of calculating data usable for designing of a composite slab decreased in cost.SOLUTION: A calculation device 1 includes: a storage unit 12 which stores a position Ae of a first neutral axis NA1 of a cross section SF1 in a first direction X of a composite slab 100; a first calculation unit 13 which calculates a position Ac of a second neutral axis NA2 of a cross section SF2 in a second direction Y of the composite slab 100; and a second calculation unit 14 which calculates a proportion of a second force Pe applied to a component in the first direction X of the composite slab 100 among a first force Pm, to the first force Pm pressing the composite slab 100 in a thickness direction Z on the basis of the position Ae of the first neutral axis NA1 and the position Ac of the second neutral axis NA2.SELECTED DRAWING: Figure 2

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 a bending moment-curvature calculation and characteristic state recognition method and system for a UHPC composite beam and a storage medium, and the method comprises the steps: obtaining geometric parameters and material parameters of the UHPC composite beam, and building a nonlinear constitutive model of each material; unit layer division is carried out on the cross section of the UHPC composite beam, and an initial value of the curvature of the cross section is given; acquiring an approximate solution of the neutral axis by using a dichotomy, and acquiring an accurate solution of the neutral axis by using a Newton method based on the approximate solution of the neutral axis; calculating strain and stress of each unit layer based on plane section assumption, and judging whether the UHPC composite beam is damaged or not; if the UHPC composite beam is not damaged, calculating the bending moment value of the UHPC composite beam, identifying the current characteristic state and recording the curvature and the bending moment value, then updating the curvature of the cross section and recalculating the accurate solution of the neutral axis; and if the damage occurs, outputting a curve of the curvature-bending moment value of the cross section. According to the method, the requirements of calculation and analysis of the composite beam under the sagging moment and the hogging moment can be met.

To reduce the weight of a body component for a vehicle while securing required strength against bending moment.SOLUTION: Provided is a body component for a vehicle. The body component includes an annular portion having a hollow portion and formed in an annular shape. The hollow portion is formed in a cross section orthogonal to the longitudinal direction of the body component. The hollow portion is configured such that a neutral axis, with respect to a bending direction assumed in advance in the cross section passes through the hollow portion. Each of separation portions includes a thick portion that is thicker than a passage portion.SELECTED DRAWING: Figure 2

This invention provides a method and system for determining the longitudinal equivalent bending stiffness and deformation of a double-circular shield tunnel. The double-circular shield tunnel is an underground prefabricated composite slender cylindrical structure assembled from precast segments connected by high-strength bolts during the tunneling process of a tunnel boring machine. Its cross-section is formed by the joining of two large circular arcs. Based on the design parameters of the double-circular shield tunnel cross-section, the corresponding bolt average linear stiffness, neutral axis position, and neutral axis position angle can be determined. Then, based on the position of the neutral axis, the longitudinal equivalent bending stiffness of the double-circular shield tunnel can be calculated using the corresponding formula. The beneficial effects of this invention are: it improves the reliability and accuracy of the longitudinal equivalent bending stiffness of the double-circular shield tunnel, provides assistance for the longitudinal structural design of double-circular shield tunnels, is of great significance for assessing the impact of adjacent construction on the double-circular shield tunnel, and further obtains deformation and stress indicators, providing a reference for the deformation and stress safety monitoring of double-circular shield tunnels.

The invention relates to a method for calculating the flexural capacity of a hogging moment area of a reinforced concrete composite beam based on a UHPC thin layer. The method comprises the steps that a test piece is prepared, measuring points are arranged, a load strain curve and a loading result graph of the test piece are obtained through a pressure loading test, and flexural performance characterization is determined. Determining an associated stress area of the composite beam according to the bending resistance characterization, presetting a first assumption condition, and performing derivation based on a strain expression, an internal force expression and a force balance equation to obtain a calculation expression of a cracking bending moment; presetting a second assumption condition, deducing and determining the position of a plastic neutral shaft, establishing a moment balance equation, and deducing according to the section strain expression, the internal force expression and the moment balance equation to obtain a calculation expression of the flexural capacity of the composite beam.

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.

A force sensor comprising a beam having a longitudinal center axis and a neutral axis that extends along a beam surface parallel to the center axis. A first half-bridge includes tension resistors. A second half-bridge includes tension resistors. A third half-bridge includes compression resistors. A fourth half-bridge includes compression resistors. The half-bridges are arranged on the beam surface such that redundant measurements of orthogonal components of a force imparted to the beam can be made using four different combinations of three of the half-bridges. The redundant measurements can be used to identify a malfunction of one or more of the resistors.

The present invention proposes for the first time a cross-section design method for concrete beams for active CO2 storage. The method first calculates and obtains the vertical distance x from the neutral axis of the concrete beam specimen to the edge of the compression zone of the cross section. c ; Then according to the vertical distance x from the neutral axis of the concrete beam specimen to the edge of the compression zone of the section c , determining whether to design a single-reinforced rectangular cross-section or a double-reinforced rectangular cross-section; based on the determination, performing the single-reinforced or double-reinforced rectangular cross-section design, and verifying the designed single-reinforced or double-reinforced rectangular cross-section. This method fills a gap in the cross-sectional design of hybrid reinforced concrete beams for active CO2 storage, thereby promoting the production and manufacturing of such concrete beams.

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 application provides a continuum robot macro-micro motion device and method based on eccentric mechanism, which comprises a plurality of unit bodies connected in sequence, any unit body comprising a rigid section and a bendable section; the rigid section of the unit body is provided with a positioning block, the middle part of the positioning block is formed with a central cavity, and the positioning block is further provided with an eccentric macro drive cavity and an eccentric micro drive cavity; a drive rope is arranged in the macro drive cavity, and a bendable fiber with an eccentric cavity is arranged in the micro drive cavity. The motion ability of the robot is enhanced by rotating the bendable fiber with the eccentric cavity, two hot-drawing polymer fibers with eccentric inner cavities are inserted into the micro drive cavity of the continuum robot, the macro motion of the robot is completed by stretching the drive rope, the micro motion is provided by the rotation of the eccentrically arranged fiber, and the basic principle of the micro motion is to rely on the slight change of the neutral axis of the continuum robot.

Force / torque sensor (10), comprising: a tool adapter plate (WAP), wherein the WAP (12) is configured to be connected to a first object: a mounting adapter plate (MAP) wherein the MAP (14) is configured to be connected to a second object; one or more deformable supports (16) which connect the WAP (12) to the MAP (14); a first pair of deformation measuring elements (1-6) attached only to one side of each support, wherein the deformation measuring elements (1-6) are spaced apart on opposite sides from a neutral axis (18) of the support (16) and are configured to convert tensile and compressive forces on the surface of one side of the support (16), which are caused by a deformation of the support (16), into electrical signals; and a measuring circuit which is designed to measure, in response to electrical signals from all deformation measuring elements (1-6), the direction and magnitude of the force and torque between the first and second objects; and a relief cut (34), parallel to the upper surface, at a distance from the upper surface which is not greater than the depth of the blind recess, through the ring-shaped body (14) and the supports (16), but not through the central area (12), wherein the relief cut defines a base to which the central area (12), but not the ring-shaped element (14) and the supports (16) are connected, and leaving the ring-shaped element (14) connected to the central area (12) only by the support (16).

The invention discloses an online measurement method and system for the dynamic deformation of a distributed wing aperture antenna main beam structure based on an FBG strain sensor. The method comprises: determining the strain of any point on the surface of a wing main beam according to a constructed nine-degree-of-freedom displacement field to obtain a constitutive relationship; determining the order of an interpolation shape function according to the constitutive relationship, and establishing an interpolation function of an inverse unit displacement field of the wing main beam; determining the neutral axis strain function of the wing main beam based on the measured strain detected by the FBG strain sensor, and obtaining a measured neutral axis strain function of any point on the wing main beam; then constructing an online evaluation model for the deformation of the wing main beam, and obtaining unknown node degrees of freedom of the wing main beam through the online evaluation model for the deformation of the wing main beam; the invention ensures that the measurement result is more accurate by considering the influence of the in-plane distortion and out-of-plane warping deformation of the wing main beam on the spatial posture of the antenna unit of an airborne platform, and realizes the nine-degree-of-freedom online perception of the wing main beam based on the online measurement of FBG strain.

The invention relates to a method for checking the positioning of a fiber preform in a blade, the blade having been obtained by injecting resin into a mold having the shape of the blade and in which the preform has been placed, the blade extending in an orthogonal blade reference coordinate system X, Y, Z, the blade comprising a blade root and an airfoil portion, the blade root extending longitudinally along an axis X, the airfoil portion extending from the blade root along an axis Z, the blade having a thickness defined along the axis Y, the preform comprising a glass tracer positioned on a surface of the preform, the center of the tracer defining a neutral axis being positioned along the axis Z in a direction defined by the axis X. At a height, the method comprises the following steps: acquiring (E31) 2D tomographic projections of the blade using an imaging system including an X-ray source, each projection being acquired at a given orientation of the X-ray source relative to the blade; accumulating (E32, E32a, E32b) the 2D projections along the direction of the axis Y to obtain an accumulated 2D image in the directions X and Z; determining (E33) a grayscale profile for each column of pixels defined along the direction of the axis Z; processing (E34) each of the obtained profiles to locate the position of the neutral axis in the direction of the axis X in Z.

The present invention discloses a simplified calculation method and system for the shear force and opening of segment joints in immersed tube tunnels. The method comprises: determining basic assumptions; then setting the relative axial and vertical deformations and relative rotation angles at the neutral axis of the joint, and clarifying the calculation method for the deformation of the concrete end spring, Ω waterstop, and shear key; then performing force analysis on the concrete per unit area of ​​the end face, the shear key, etc., deriving force formulas, and clarifying the expressions and force mechanisms for the axial force, shear force, and bending moment; considering the extreme conditions of overall heating and cooling, deriving the heating using an elastic foundation beam model and treating the cooling as an articulated joint, and simulating using three-dimensional finite element software; finally, determining the influencing factors and assumptions based on longitudinal three-dimensional model parameter analysis, establishing and deriving a simplified theoretical calculation model, and verifying the formula by comparing the results of the three-dimensional calculation model. This method achieves efficient and accurate calculation of the shear force and opening of segment joints.