14 results about "Crack tip opening displacement" patented technology

The invention relates to the field of test methods, in particular to a method for estimating the fatigue crack growth rate of a corrosion-resistant metal composite material, which comprises the following specific steps: S1, preparing a sample, and measuring and recording the thickness B, the width W and the machining notch length am of the sample; s2, prefabricating fatigue cracks; s3, selecting test parameters; s4, carrying out a fatigue crack growth rate test; s5, calculating the opening displacement variation (delta delta) of the crack tip; s6, forming a data group, analyzing a distribution rule and establishing a mathematical model; and S7, carrying out damage tolerance design and fatigue life check. According to the method, the crack tip opening displacement variation delta delta is used as a driving parameter to describe the fatigue crack propagation rule of the corrosion-resistant low-strength high-plasticity metal material and the composite material of the high-strength low-plasticity metal material; the method can solve the crack propagation problem that K is only suitable for elastic or small-range yield and r cannot be fully covered under the condition of plastic yield.

The invention discloses a fracture toughness prediction method for a non-continuous bionic Brini-gang structure, and belongs to the field of bionic composite material design. The prediction method comprises the following steps: S1, acquiring geometric and material parameters of a discontinuous bionic Belii Vagina structure; s2, constructing a fracture mechanics theoretical model of the structure; s3, solving the opening displacement of the fracture tip of the bionic Belii gang structure by adopting a numerical method; and S4, calculating parameters such as a crack propagation resistance curve and fracture toughness according to the crack tip opening displacement. According to the fracture toughness prediction method of the non-continuous bionic Beliolian structure provided by the invention, fracture parameters such as crack tip opening displacement and a crack propagation resistance curve can be obtained by taking microscopic sizes and material parameters of fibers and a matrix of the structure as input, and the prediction method not only can reveal fracture characteristics and a toughening mechanism of the bionic Beliolian structure, but also can obtain fracture parameters such as fracture toughness of the bionic Beliolian structure. And the method can also be used for optimal design of a bionic Brini spine structure.

The invention relates to the technical field of steel rail damage, and provides a near-field dynamics simulation method for steel rail head multi-crack competitive propagation, which comprises the following steps: establishing a near-field dynamics plane stress model of a steel rail head and dispersing the near-field dynamics plane stress model into particles; defining a particle interaction domain by adopting a double-vision-field key-based near-field dynamics method; setting boundary conditions and introducing a plurality of initial cracks on the surface of the rail head; applying a load to simulate a wheel-rail rolling contact process; simulating a multi-crack competitive expansion behavior based on the fracture state and fatigue life evolution of the key; and the interaction between the cracks is quantified by calculating the opening displacement and the sliding displacement of the crack tip. According to the method, the limitation that only a single crack can be simulated in the prior art is overcome, competitive expansion high-precision simulation of multiple cracks under the dynamic load is realized, the experiment cost is remarkably reduced, and a scientific basis is provided for steel rail fatigue damage assessment and maintenance decision making.

The invention relates to the field of test methods, in particular to a method for evaluating the service life of a metal material in the whole corrosion fatigue crack propagation process, which comprises the following specific steps: S1, designing a corrosion environment device; s2, preparing an etchant solution; s3, selecting and measuring the size of a sample; s4, prefabricating fatigue cracks; s5, setting test parameters and performing a test; s6, calculating the opening displacement variation (delta delta) of the crack tip; s7, establishing a mathematical model; and S8, evaluating the service life. According to the novel method for simultaneously describing the processes of the three stages of corrosion fatigue crack propagation, the processes of the three stages of corrosion fatigue crack propagation are well described by taking the crack tip opening displacement variable quantity containing elastic and plastic displacement superposition as a driving parameter; the method can provide a technical basis for whole-process life evaluation of corrosion fatigue crack propagation, and meets the requirements of fatigue life evaluation of ocean engineering components.

A method for evaluating the crack propagation life of complex three-dimensional constrained metal structures is disclosed, enabling efficient assessment. The method includes: implanting a crack at a specified location in a real structure and obtaining the far-field stress of the crack in the real structure; establishing a finite element model of an infinitely large plate and implanting a central crack; calculating the crack tip opening displacement and the infinitely large plate crack tip opening displacement in a manner consistent with the parameters of the central crack in the real structure; calculating the stress intensity factor of the infinitely large plate and comparing the crack tip opening displacement with that of the infinitely large plate to obtain the stress intensity factor of the real complex structure; repeating the preceding steps by adjusting the crack length in the real structure to obtain the crack tip stress intensity factor for different crack lengths; and interpolating the relationship between each crack length and the corresponding crack tip stress intensity factor to calculate the crack propagation life of that crack segment.

The present invention discloses a method for testing the propagation toughness of rock cracks under static loads by combining DIC and strain gauges. The method comprises applying a static load to a cracked rock specimen, then calculating the real-time crack tip opening displacement in the crack propagation path using a numerical image processing system (DIC), obtaining the crack propagation velocity based on the crack tip opening displacement, obtaining the propagation toughness value of the rock crack propagation process under static load, and evaluating the rock crack propagation process using the propagation toughness value. The present invention uses an industrial camera and a strain gauge to simultaneously measure the crack initiation time, accurately determining the initiation time of the rock crack, providing a better experimental data basis for the subsequent determination of the crack propagation velocity and calculation of the crack propagation toughness, and using the crack initiation toughness and crack propagation toughness to evaluate the strength of the cracked rock, thereby achieving further application of the crack propagation velocity data and enabling the evaluation of the entire crack propagation process of the rock specimen.

The application discloses a crack propagation resistance curve generation method for bridged toughening biomimetic spiral structure and belongs to the field of composite material design. The prediction method comprises the following steps: acquiring geometric and material parameters of the biomimetic spiral structure; constructing a crack bridging fracture mechanics theoretical model of the biomimetic spiral structure; given a crack propagation length, solving a crack tip opening displacement by using a Newton iteration method; obtaining a fracture toughness by using the crack tip opening displacement; judging whether a steady state propagation stage is entered, if yes, obtaining a crack propagation resistance curve; and if not, increasing the crack propagation length. The application can quickly obtain fracture parameters such as the crack tip opening displacement and the crack propagation resistance curve by comprehensively considering structural heterogeneity, anisotropy and three-dimensional characteristics of the fiber spiral structure, and provides a technical approach for the toughening design of the biomimetic spiral structure.

The present invention relates to a thick steel plate for a container with high strength and low welding crack sensitivity. The chemical composition of the steel plate is as follows by mass percentage: C: 0.04%-0.06%, Si: 0.15%-0.30%, Mn: 1.60%-1.70%, P≤0.005%, S≤0.001%, Ni: 0.05%-0.13%, Cr: 0.20%-0.30%, Mo: 0.10%-0.20%, Nb: 0.01%-0.02%, V: 0.08%-0.15%, Al: 0.01%-0.02%, Cu≤0.02%, B≤0.003%, Zr: 0.003%-0.008%, V+Zr≤0.15%, and the balance is Fe and unavoidable impurities. The steel plate of the present invention has a yield strength of ≥700MPa; a tensile strength of 800-950MPa; an elongation of ≥19%; an impact energy absorption at -50°C of ≥100J; and a crack tip opening displacement CTOD value of δ R Between 0.800 and 0.820; the crack extension Δa is between 0.62 and 0.65, and the low welding crack sensitivity coefficient Pcm≤0.22.

The present application provides a high-toughness high-crack tip opening displacement LNG receiving station thick-walled seamless steel pipe steel and a method for producing a seamless steel pipe, the composition satisfies: 125.0<=A<=150.0, A=467*(%C+%N)+35*%Mn+30*(%Cr+%Ni)+10*%Mo+3*%V+15*%Si+28*%Cu; Y>=1.0%, Y=10*%Ni+6*%V+5*%Mo+15*%N-20*%C-3*%Mn+8*%Cu-2*%Si. The present application produces a 40-60mm thick-walled seamless steel pipe for LNG receiving station through component design and production method, heat treatment design, the tensile strength of the product at 1 / 2 wall thickness is >=720MPa, the yield strength is >=640MPa, -50 DEG C KV2 is >=200J, and a high-toughness high-crack tip opening displacement thick-walled seamless steel pipe for LNG receiving station is obtained.

Provided is a thick steel sheet that has a thickness exceeding 100 mm, and that has high strength, as well as excellent low temperature toughness, excellent deformation performance in the sheet thickness center section, and excellent crack tip opening displacement (CTOD) property of a multi-layer weld joint. The thick steel sheet comprises, in mass %, C: 0.03-0.20%, Si: 0.50% or less, Mn: 0.3-3.0%, P: 0.030% or less, S: 0.0050% or less, Al: 0.005-0.100%, B: 0.0001-0.0050%, N: 0.0100% or less, and O: 0.0100% or less, and at least one selected from the group consisting of Cr: 0.01-2.00%, Mo: 0.01-2.00% and Ni: 0.01-5.00%, with the remainder being Fe and inevitable impurities. The steel sheet has a component composition satisfying formula (1). The maximum prior austenite grain size of the sheet in the section at the center of the sheet thickness is 150 μm or less. The number density of porosities having an equivalent circle diameter of 100 μm or more is 0.10 pcs / mm2 or less. The number density of MnS having a thickness of 30 μm or more in the plate thickness direction is 10 pcs / mm2 or less. The sheet thickness exceeds 100 mm.

The invention discloses a crack propagation resistance curve generation method for a bridging toughening bionic spiral structure, and belongs to the field of composite material design. The prediction method comprises the following steps: acquiring geometric and material parameters of the bionic helical structure; constructing a crack bridging fracture mechanical theoretical model of the bionic spiral structure; giving a crack propagation length, and solving a crack tip opening displacement by adopting a Newton iteration method; calculating the fracture toughness by using the crack tip opening displacement; judging whether a steady-state propagation stage is entered or not, and if yes, obtaining a crack propagation resistance curve; if not, increasing the crack propagation length. According to the method, structural heterogeneity, anisotropy and three-dimensional characteristics of the fiber spiral structure are comprehensively considered, fracture parameters such as crack tip opening displacement and a crack propagation resistance curve can be rapidly obtained, and a technical approach is provided for strengthening and toughening design of the bionic spiral structure.

The invention relates to the technical field of ship and ocean engineering, and particularly discloses a semi-submersible platform fatigue strength evaluation method, through which the fatigue damage condition of a structure at the most vulnerable hot spot position can be efficiently and accurately evaluated in the actual operation process of a semi-submersible platform, and the fatigue strength of the semi-submersible platform can be evaluated by evaluating and adjusting the loading and subsequent operation states of the structure in real time. And hidden risks caused by fatigue damage of the semi-submersible platform are reduced to the maximum extent. And the current damage condition of the semi-submersible platform can be quickly predicted based on numerical data obtained by a high-precision simulation model and real-time stress-strain field and crack tip opening displacement data obtained by a monitoring system. Meanwhile, black box processing is performed on the data through digital twinning, so that the problem of time consumption of calculation can be avoided, and the survival rate of the semi-submersible platform is greatly improved.

The invention belongs to the field of material mechanical property testing, particularly relates to an alkaline low-hydrogen welding rod for X80 manual welding for repair and a manufacturing method thereof, and solves the problem that the alkaline low-hydrogen welding rod for repair welding in X80 pipeline engineering meets high toughness of weld fracture toughness CTOD 0.254 mm. The tensile strength of a repair welded junction of a ring welding joint formed by conducting repair welding through the alkaline low-hydrogen welding rod manufactured through the method is not lower than 625 MPa; the fracture toughness test value of the welding seam and the heat affected zone is greater than or equal to 0.254 mm; the hardness value of weld metal and a heat affected zone of the repaired welded junction is not larger than 300 HV10 through root welding, and the hardness of other zones is not larger than 325 HV10; the single value of the Charpy impact toughness of the repaired welded junction at-20 DEG C is not less than 38J, and the average value is not less than 50J.

The application provides a data processing method for corrosion fatigue test, a storage medium and an electronic device, and the data processing method comprises the following steps: S1: acquiring crack tip opening displacement variation-crack length data groups of a first stage and a second stage and a third stage in a corrosion fatigue crack propagation test, respectively; S2: inverting the first stage data; S3: performing data translation correction; S4: fusing and fitting all-stage data; the corrected first stage data group (Delta delta, a1'') and the second stage and third stage data group (Delta delta, a2) are combined to obtain a (Delta delta, a) data group of the corrosion fatigue crack propagation of all stages, and a Delta delta-a relationship model is fitted. The application is aimed at the problem that the Delta delta-a decrease in the K reduction method threshold test is inconsistent with the actual crack propagation increase law of marine engineering, the first stage data is inverted symmetrically and translationally corrected, the all-stage Delta delta-a data is monotonously increased and connected, and the application can be used for the corrosion fatigue full life evaluation of marine engineering structures.