Provided is an apparatus for fatigue testing a bulge tool having a WH-type skeleton, the apparatus including: a fixing bracket having tool holes penetrated through opposite sides thereof; a tool housing coupled to the tool hole of the fixing bracket and having the bulge tool inserted and installed therein; a moving rail installed at one side of the fixing bracket in a lengthwise direction of the tool housing and providing a reciprocating movement path facing the tool housing; a moving bracket reciprocating along the moving rail; a pusher protrudingly installed from the moving bracket toward the tool housing and moving in and out of the bulge tool; a measurement means installed between the pusher and the moving bracket, measuring a load applied to the bulge tool; and a drive means for generating power reciprocating the moving bracket on the moving rail.

The present invention relates to alternating stress fatigue testing equipment. The alternating stress fatigue testing equipment includes a pedestal on which linear guide rails are arranged; a deflection loading device which is arranged on the pedestal and configured to, in response to a clamped to-be-measured object being driven to slide to a first position, enable the to-be-measured object to be bent to a target degree and keep the to-be-measured object after the to-be-measured object is bent to the target degree, wherein the deflection loading device is rotatably connected to the to-be-measured object; two hinged shaft supports which are arranged on the linear guide rails, wherein the hinged shaft supports are symmetrically arranged about a longitudinal center line of the deflection loading device, connected to both ends of the to-be-measured object respectively, and configured to be adjusted obliquely to adapt to the bending of the to-be-measured object to the target degree.

The present invention discloses a multiaxial creep-fatigue prediction method based on ABAQUS, which comprises: S1: establishing an ABAQUS finite element model, and defining the viscoplastic constitutive equation of the material to be tested by means of the user subroutine UMAT; S2: determining the model parameters required by the viscoplastic constitutive equation; S3: establishing the fatigue damage calculation model and creep damage calculation model of the multiaxial stress-strain state of the material to be tested; S4: establishing an ABAQUS finite element model under the multiaxial stress-strain state, and calculating the stress-strain tensor of each cycle based on the defined viscoplastic constitutive equation and the model parameters; S5: calculating the equivalent stress and equivalent plastic strain by means of the user subroutine USDFLD, and superimposing the fatigue damage and creep damage of each cycle according to the linear cumulative damage criterion to obtain the crack initiation life of the material to be tested based on the fatigue damage calculation model and creep damage calculation model in combination with the stress-strain tensor.

An apparatus for introducing a test load to a rotor blade test specimen for fatigue testing includes a body extending along a longitudinal axis in a first direction from a first end to a second end, and the body having an internal cavity with an opening at the second end configured to dispose a tip portion of the rotor blade test specimen.

A tension load fixture for applying tension or loading forces to a specimen comprises a pair of tension arms and an imaging device. The pair of tension arms are configured to releasably couple to opposite end regions of a specimen and to apply tension or loading forces to the specimen. The specimen is configured to be positioned between the pair of tension arms and defines a notch between the opposite end regions of the specimen. The notch extends from a side of the specimen to a middle region of the specimen. The imaging device is configured to capture one or more images of the middle region of the specimen and is configured to rotate about a central axis of the tension load fixture that is proximate to the middle region of the specimen to facilitate generation of a three-dimensional image of the middle region of the specimen as the specimen is subjected to tension or loading forces.

Discussed is a fatigue failure verification device that can include a module housing including a welding portion, a cell stack including a plurality of battery cells accommodated in the module housing, at least one main flexible tube located in a central portion of the cell stack in a stack direction of the cell stack, a main flexible tube frame in which the at least one main flexible tube is accommodated. The main flexible tube frame can include a pair of opening portions formed on opposite sides so that the at least one main flexible tube faces the plurality of battery cells, and a pump can be provided, which is configured to adjust a pressure applied by the at least one main flexible tube to the plurality of battery cells by supplying a fluid to the at least one main flexible tube.

An evaluation method for corrosion damage evolution of underwater concrete structures includes performing the time reversal test on the concrete beam specimen placed in the water, performing the uniaxial compression test on the concrete cube specimens; immersing the concrete beam specimen and the concrete cube specimens in a hydrochloric acid solution, and performing the time reversal test on the concrete beam specimen on the 10th, 20th and 30th days respectively. At the same time, a concrete cube specimen is taken out to perform the uniaxial compression test on the 10th, 20th and 30th days respectively; and using the above calculation results to evaluate the corrosion evolution process thereof without damaging the underwater concrete structure.

A method for evaluating damage-healing characteristics of paving asphalt based on energetics principle includes: obtaining a numerical integral A.sub.H of a stored pseudo strain energy required by asphalt to compensate damage-healing to loading times and obtaining local life compensation ΔN of the asphalt benefiting from damage-healing characteristics; calculating an average stored pseudo strain energy Q.sub.H of the asphalt according to the following

[00001]$Q_H=\frac{A_H}{\Delta N};$

and evaluating the asphalt damage-healing characteristics according to the average stored pseudo strain energy Q.sub.H of the asphalt. This method is based on the evolution law of the average stored pseudo strain energy required to compensate the damage-healing to explore the damage-healing characteristics of asphalt. As a characteristic index of materials, this energy evaluation index has nothing to do with the damage state and the rest periods, but only depends on the strain load, which improves the testing efficiency.

A method for quickly predicting a fatigue life of a wrinkle defect-containing main spar in a wind turbine blade is provided. The method includes: S1: testing a tensile property of a wrinkle defect-containing main spar to be tested; S2: calculating, according to surface temperature data of the specimen obtained in step S1, intrinsic dissipated energy of the main spar specimen under different loading stresses; S3: plotting a relational graph between intrinsic dissipated energy of the specimen and a corresponding ultimate tensile strength (UTS) level; S4: establishing, based on a change of the intrinsic dissipated energy in a fatigue process, a normalized residual stiffness model containing parameters to be determined, and putting fatigue test data into the model; S5: deducing a fatigue life prediction model for the wrinkle defect-containing main spar specimen according to the normalized residual stiffness model with determined parameters; and S6: obtaining a normalized failure stiffness.

Due to geometric discontinuities introduced by welding and joining processes, stresses or strain cannot be calculated reliably calculated using modern analytical and computer methods as result of stress or strain singularity at joint locations, which leads to severe mesh sensitivity. Design and fatigue evaluation of these structures remain empirical. This disclosure addresses mesh insensitivity of stress/strain calculations for welded structures through a cut-plane traction stress method through a novel post processing of conventional finite element computation results, as well as provides a unified fatigue evaluation procedure for fatigue design and structural life evaluation for both low-cycle and high cycle fatigue regime subjected to either proportional or non-proportional multiaxial fatigue loading, as well as a simple and reliable method for treating spot welds.