52 results about "Compact tension specimen" patented technology

The invention discloses a method for measuring high-temperature creep crack growth threshold value of material. The method comprises the following steps of: for a specific material, according to the creep crack growth test requirement, processing at least 6 standard compact tension specimens, performing crack prefabrication for the well processed at least 6 specimens on a fatigue performance tester, wherein the prefabricated crack length is 0.5 times of the width of each specimen; wedging a wedge-shaped block into an initial notch of each specimen, placing the headmost end of the straight part of the wedge-shaped block at the position of a loading line, providing displacement for the loading line, forming a stress-strain field characterized by a stress strength factor at the tip of the specimen crack, and providing a driving force for the creep crack growth, wherein the specimens with different initial stress strength factors grow after certain time under creep effect in high-temperature environment, and in the same time interval, the crack growth lengths are different; drawing for the different stress strength factors and the corresponding crack growth rates, and solving the creep crack growth threshold value of the material through an extrapolation method. According to the method provided by the invention, multiple specimens can be tested for one time, and thus, the test cost is greatly reduced and the test time is greatly shortened.

The invention discloses a method for measuring stress corrosion crack propagation rate by employing slow strain rate tensile. The method comprises the following steps: 1. preprocessing a compact tension specimen; 2. carrying out a slow strain rate tensile test by adopting a slow lifting testing machine, and drawing an experimental data relationship graph between loading force P and loading point displacement deltaL; 3. simulating the slow strain rate tensile test carried out in the step 2, and drawing a theoretical analysis data relation graph between the loading force P and the loading point displacement deltaL; 4. obtaining corresponding test time t0, t1, t2,..., tn when the crack propagation lengths are deltaa0, deltaa1, deltaa2,..., deltaan; 5. obtaining the crack propagation rate. By adopting the method, the change of the loading force P and loading point displacement deltaL caused by crack propagation can be separated out, and the change of the deltaai can be predicted in real time, so that the crack propagation rate is obtained. Thus, test data distortion caused by environmental influence can be effectively alleviated, and the data accuracy is improved.

The invention belongs to material mechanics property testing equipment, and provides a clamp for a compact tension specimen of a material testing machine under a high pressure hydrogen environment. The clamp comprises an upper clamp and a lower clamp, the upper clamp comprises an upper support, an upper primary U-shaped clamp, an upper secondary U-shaped clamp and dowels. The two ends of the upper support (the periphery of a cylindrical part) are respectively provided with a screw hole and are connected with the upper end of the testing machine through screws, two opposite rectangular blocks in the middle part of the upper support constitute a clamping interval, the two rectangular blocks and the cylindrical part of the upper support are machined to be of an integrated structure, and all the above components belong to the support part. The clamp for the compact tension specimen of the material testing machine under the high pressure hydrogen environment has the advantages that the misalignment influence can be eliminated automatically in the testing process of the compact tension specimen, it is guaranteed that the compact tension specimen is only subjected to the one-way loading action, the additional bending moment can be avoided, hence, the accuracy of test data is improved, using is simple and convenient, and the clamp is particularly suitable for material compact tension tests under the high pressure hydrogen environment.

The invention provides a device and a method for testing breaking tenacity of a compact tension specimen in a low-temperature environment. The device comprises an insulated container for containing low-temperature liquid medium, upper and lower clamps and a displacement transmitting mechanism, wherein a specimen is soaked in low-temperature liquid medium and comprises a crack mouth in a horizontal orientation; the upper and lower clamps are connected with the specimen, respectively arranged at two sides of the crack mouth, and respectively connected with upper and lower pistons of a tensile testing machine; the displacement transmitting mechanism comprises two vertical guide rails which are parallel and slide oppositely; upper and lower blades are respectively arranged at two ends of the each vertical lead rail; the upper blades of the two vertical guide rails are oppositely arranged to form an upper tool edge connected with an extensometer; the lower blades of the two vertical guide rails are arranged oppositely to form a lower tool edge connected with the crack mouth, so that a loaded line displacement of the specimen is transferred to the extensometer above the liquid level of the low-temperature liquid medium, so as to accurately measure the loaded line displacement. Meanwhile, the extensometer is prevented from directly contacting the low-temperature liquid medium to be easily damaged, and the device and the method are simple and reliable in structure, and convenient to install and operate.

The invention discloses a novel method for measuring compact tension specimen fracture parameters by using double extensometers. The novel method comprises the following steps of: measuring two opening displacements by using the double extensometers; obtaining a crack tip opening displacement (CTOD) of a compact tension test through calculation by using a triangular relation; and calculating a CTOD value under each load and a nominal stress corresponding to the CTOD value, and obtaining a relation between the nominal stress and the CTOD, thereby obtaining a CTOD design curve of the compact tension test. The fracture parameter test method disclosed by the invention has the characteristics of simpleness, easy operation, simpleness for processing data, high precision of a critical CTOD value, comprehensive data, large information quantity, freeness from test precision influences of other parameters, such as strength, Young modulus, rotary factor and load, capabilities of obtaining the CTOD data of the whole test loading process and obtaining the CTOD design curve of the compact tension test under an actual board thickness condition.

The invention relates to a device and a method for measuring crack expanding rate of a compact tension specimen, which are applied to continuous high-accuracy measuring of fatigue crack expanding, stress corrosion cracking, corrosion fatigue and other experiments of the compact tension specimen. The device comprises the following hardware of a computer, a GPIB (general purpose interface bus ) card, a multi-channel high-power relay card, a high-accuracy nanovolt micro-ohmmeter, a data switching unit, a high-stability direct current power supply, a shielding conducting wire or a double-strand insulation platinum wire. The device comprises the following software of direct current potential drop crack expanding rate measuring software and a user interface thereof. The device has the advantage that the relay switch is controlled by the direct current potential drop crack expanding rate measuring software to reversely change the direction of the direct current, so as to solve the problem of interference to the measuring accuracy and stability by the contact resistances of lead wire and specimen and electric potential produced by the temperature difference at both ends of the lead wire.

The invention discloses a sample component and method for a nuclear power plant reactor pressure container irradiation inspection test. The component comprises a tensile sample, an impact sample and a compact tensile sample, wherein the tensile sample is used for acquiring the tensile strength, the yield strength, the elongation and the cross section reduction ratio of irradiated materials, the impact sample is used for acquiring impact toughness of the irradiated materials, the compact tensile sample is used for acquiring fracture toughness of the irradiated materials and provided with notches, circular portions and side grooves which are sequentially formed in a first side face and a second side face from top to bottom, and the notch with an isosceles trapezoidal section, the circular portions and the notch with a V-shaped bottom jointly form an extensometer placement space. The method includes the steps of sample preparation, sample loading, sample testing and result evaluation. Arrangement of a bent sample is canceled, the quantity proportion of the other samples is optimized, the shape of the compact tensile sample is optimally improved, and test failure risks in fracture toughness testing are decreased.

The invention discloses a method for measuring critical temperature of high temperature creep crack growth of a material. The method comprises the following steps of: processing not less than 6 standard compact tension specimens through a specific material according to creep crack growth test requirements, performing crack prefabrication on the processed not less than 6 test specimens on a fatigue performance tester, wherein the prefabricated crack length is 0.5 times as large as the width of the test specimen; wedging a wedge-shaped block in an initial slot of the test specimen, locating the most front end of the flat part of the wedge-shaped block at a loading line to provide displacement to the loading line, and forming a stress strain field characterized by stress strength factors at the crack tip of the test specimen to provide a driving force for creep crack growth; and putting the assembled test specimen in a resistance wire heating type high temperature furnace to perform heating test or cooling test until the crack growth speeds of all test specimens at a temperature are not larger than 1*10<-6>m/h, and the temperature is the critical temperature of high temperature creep crack growth of the material. The method disclosed by the invention can be used for testing a plurality of test specimens at one time, so that the test cost is greatly lowered.

The invention discloses a test method for a crack growth rate of a linear gradient material. The test method comprises the following steps: applying alternating load to a compact tension specimen through a fatigue test machine; rewriting a function relationship of parameters at a test control end; introducing a gradient correcting item for measuring crack length and a gradient correcting item for calculating load; and accurately controlling a test progress and automatically correcting, thereby acquiring test data and acquiring the crack growth rate of the gradient material. The test method provided by the invention has the advantages that the test method is fit for testing the crack growth rate of the linear gradient material, no human intervention is required in the testing period, the test is automatically performed and the precision is high.

The invention discloses a method for measuring high-temperature fracture toughness JIC of high-toughness alloys, and relates to the technical field of fracture mechanics. The method comprises the steps of processing a compact tension specimen and forming a V-shaped slot in the tip position of a gap in the side surface of the specimen; carrying out fatigue crack prefabrication on the specimen; carrying out a tension test after heating and heat preservation so as to obtain a load displacement curve, snapping the specimen after cooling, and measuring the lengths of quasi-static cracks; regularizing the load displacement curve and carrying out parameter fitting to obtain a load displacement fitting curve; and iteratively calculating the lengths of the cracks, fitting the test data to obtain aresistance curve, and solving a JIC value. The method for measuring the high-temperature fracture toughness is disclosed on the basis of a load separation method, the high-temperature load displacement curve of the compact tension specimen is processed through a regularization method, and the length of the quasi-static crack corresponding to each point on the curve is iteratively calculated, so that a J integral value is effectively measured and then the high-temperature fracture toughness is calculated.

The invention discloses a method for measuring the expansion rate of an intrinsic fatigue crack of a welded plate vertical to the weld direction, and belongs to the technical field of solid mechanics. The method comprises the following steps: at first, measuring residual stress horizontal to the weld direction; making a welded plate into a weld containing compact stretch sample, wherein the crack expansion direction is vertical to the weld direction; calculating the stress strength factor of residual stress corresponding to different crack lengths; through a residual stress superposition model, by combining a given constant stress factor range and a constant effective stress ratio, calculating the applied external loads under different crack lengths; carrying out fatigue crack expansion experiments under the calculated external loads, and determining the expansion rate of an intrinsic fatigue crack in a welded member under a given constant stress factor range and constant effective stress ratio. The provided method can directly obtain the expansion rate of an intrinsic fatigue crack in a welded member under a given stress state through fatigue experiments, is simple, and has a high accuracy.

Embodiments of the invention disclose a compatibility evaluation method and system for a material loaded based on constant displacement and high-pressure hydrogen. Based on a fracture mechanics theory, a compatibility test method for the material in a static seal isolation environment and the high-pressure hydrogen is carried out by adopting a compact tension specimen (CT specimen) and a bolt loaded compact tension specimen (WOL specimen); through the test method, the crack hydrogen induced cracking sensitivity of the specimen material in the constant displacement loading state and a criticalstress intensity factor value KIH of the bolt loading compact tension specimen in a high-pressure hydrogen environment can be measured; material parameters obtained according to the method disclosed by the invention not only can be used for measuring the applicability of the material in the high-pressure hydrogen environment, but also can provide necessary design parameters for the design and manufacture of hydrogen environment service equipment; and a test process can be remotely monitored, so that the test personnel can be prevented from being in close contact with the hydrogen high-pressuretest device, and the test risk is reduced.

The invention provides an anti-warping device of compact tension samples. The anti-warping device can be used for preventing warping deformation of samples in detecting of thin plate material K-R curve without changing stress distribution situations of the samples or influencing crack observation in tests. The anti-warping device comprises rectangular anti-warping plates 3, stepped gaskets 5, connecting bolts 6, horizontal backing plates 7, a vertical backing plate 8, and a device button rope 9; wherein the rectangular anti-warping plates 3 are two steel plates with identical shapes, the two horizontal backing plates 7 and the vertical backing plate 8 are steel plates with a thickness of 0.2 to 0.3mm thicker than that of the samples.

The invention discloses a fatigue crack propagation simulation method for CT (Computed Tomography) sample of a three-dimensional linear friction welding head, and belongs to the field of solid-phase welding and fracture mechanics. The method comprises the following steps of establishing a three-dimensional linear friction welding model; firstly, after a three-dimensional linear friction welding model is established in finite element simulation software ABAQUS, submitting operation simulation welding in a job module to acquire a linear friction welding head; then, selecting a micro-area compact tensile sample area, and drawing a stress nephogram sketch; finally, establishing a linear friction welding joint micro-area crack propagation compact tensile sample model, and respectively importing the iges files in the three directions obtained in the step 2 into sketch modules of the three compact tensile sample models; and acquiring crack propagation results in three directions so that the crack propagation trend of the three-dimensional linear friction welding head is estimated. According to the simulation method, a new thought is provided for research on the fracture behavior of the welded joint, and a large amount of pretreatment and calculation time can be shortened.

The invention discloses a method for predicting a creeping incubation period containing residual stress under a plastic transient creeping condition. A prediction model for the creeping incubation period considering the residual stress is proposed; by utilizing a referential stress method, an elastic following factor Z is introduced so as to calculate the creeping incubation model considering theresidual stress; a compact tension specimen (CT) is pre-compressed to produce the residual stress, and main load is applied to carry out a creeping experiment. The method disclosed by the invention has the beneficial effects that a creeping incubation period prediction model under a modified elastic transient creeping condition is proposed, so that the simplified method for predicting the creepingincubation period under the transient creeping condition is provided; therefore, the creeping incubation period under the elastic transient creeping condition can be simply and effectively predictedin the structure.

The invention discloses a method for predicting a creep incubation period of a high-temperature structure by coupling residual stress and a restraint effect under an elastic transient creep condition,and provides a creep incubation period prediction model coupling the residual stress and the restraint effect on the basis of Davis work. A reference stress method is utilized, and an elastic following factor Z is introduced to calculate the creep incubation period considering the residual stress. A compact tensile specimen (CT) is used to generate residual stress through pre-compression, and a main load is applied to carry out a creep experiment. According to the method, the creep incubation period under the elastic transient creep condition can be simply and effectively predicted in the structure.

The invention discloses a prediction method for a creep inoculation period considering a residual stress under a plastic condition. On the basis of Davies work, the prediction model for the creep inoculation period considering the residual stress is provided. By means of a reference stress method, an elastic follow factor Z is introduced to calculate the creep inoculation period considering the residual stress. The residual stress is generated through pre-compression by using a compact tensile sample (CT), and a main load is applied to perform a creep test. The method has the beneficial effects that an original prediction model can be expanded into a model comprising the residual stress, and the simplified prediction method for the creep inoculation period under the plastic condition is provided, so that the creep inoculation period under the plastic condition can be concisely and effectively predicted in a structure.

The invention discloses a fabrication method for a compact tension specimen used for performance testing of a material. The method comprises the following steps: 1, coarse grinding of a deep groove: a, selecting a first grinding wheel with a hardness in a range of grade L to grade N, grinding the first grinding wheel in a left-and-right symmetrical grinding manner, wherein the actual thickness of the ground first grinding wheel is 0.02 to 0.12 mm smaller than designed width of the groove, and then coarsely grinding a straight groove part with the first grinding wheel; and b, carrying out secondary grinding on the first grinding wheel in the left-and-right symmetrical grinding manner and coarsely grinding a sharp-angled part with the first grinding wheel; and 2, fine grinding of the deep groove: c, selecting a second grinding wheel with a hardness in a range of grade L to grade N, grinding the second grinding wheel in the left-and-right symmetrical grinding manner, wherein the actual thickness of the ground second grinding wheel is 0.01 to 0.025 mm smaller than the upper limit value of the designed width of the groove, and then finely grinding the straight groove part with the second grinding wheel; and d, carrying out secondary grinding on the second grinding wheel in the symmetrical grinding manner and finely grinding the sharp-angled part with the second grinding wheel. The deep groove in the specimen fabricated by using the method has high precision and ideal surface quality.

The invention discloses a predicating method for a creep incubation period containing residual stress under an elastic transient creep condition. On the basis of Davies work, a predicating model for the creep incubation period taking residual stress into consideration is disclosed; a reference stress method is utilized, and an elastic following factor Z is introduced to calculate a creep incubation period taking residual stress into consideration. A compact tensile specimen (CT) is pre-compacted to generate residual stress, and main load is applied to perform a creep test. The predicating method for the creep incubation period has the beneficial effects that the original predicating model can be expanded into a model containing the residual stress, so that a simplified predicating method for the creep incubation period under the transient creep condition is disclosed, and the creep incubation period can be simply and effectively predicated under the elastic transient creep condition inthe structure.

The invention relates to a sample for measuring high temperature fracture toughness and a preparation method thereof. The sample comprises a sample body with a gap in the left end, the left end of the sample body is connected with an additional cutter point, a line cutting groove is formed in the additional cutter point, and the line cutting groove penetrates through the additional cutter point and is communicated with the gap. The upper side edge and the lower side edge of the line cutting groove are connected with locating baffles respectively, and a T-shaped structure is formed. The locating baffles are oppositely arranged, and cutter point locating grooves are formed in the middles of the locating baffles respectively. The compact tensile sample capable of being used for the metal material fracture toughness testing experiment under high-temperature conditions, the line cutting groove is formed, and therefore the sample and a high-temperature COD gauge can be clamped and matched conveniently. The cutter point locating grooves are formed, so that the situation that due to the fact that the high-temperature COD gauge slides and even slides out, the experiment is not precise or fails is avoided. Due to the fact that the additional cutter point and the sample are integrally machined, the assembly problem before the experiment is avoided, therefore, the sample can be clamped on a machine conveniently, meanwhile, the clamping precision of the sample is guaranteed, and finally the accuracy and effectiveness of the experiment of the sample are guaranteed.

The invention discloses a predicating method for a creep incubation period containing residual stress under an elastic condition. On the basis of Davies work, the predicting model for the creep incubation period taking residual stress into consideration is disclosed. A reference stress method is utilized, and an elastic following factor Z is introduced to calculate the creep incubation period taking residual stress into consideration. A compact tensile specimen (CT) is pre-compacted to generate residual stress, and main load is applied to perform a creep experiment. The predicating method forthe creep incubation period has the beneficial effects that the predicting model for the creep incubation period under the corrected elastic condition is disclosed, and compared with an existing model, the method can expand the original predicating model into the model containing residual stress.