35 results about "Failure strain" patented technology

The invention belongs to the field of road engineering, and particularly relates to a hyperviscous and high-elastic asphalt modifier applicable to steel bridge deck pavement. The asphalt modifier comprises the following raw materials in parts by weight: 3-10 parts of junked tire rubber powder, 3-10 parts of polyethylene wastes, 3-8 parts of styrene-butadiene-styrene block copolymer, 1-5 parts of styrene-isoprene-styrene block copolymer, 1-5 parts of terpene resin, 5-10 parts of solvent naphtha, and 0.3-0.7 part of alcohol ether carboxylate adhesion agent. In addition, a modified asphalt and amodified asphalt mixture are prepared on the basis of the modifier, the 60 DEG C dynamic viscosity of the modified asphalt prepared by applying the modifier can reach more than 300000Pa.s, and the performance grading reaches PG 88-28; and the asphalt mixture has favorable water stability, higher dynamic modulus, higher track dynamic stability and low temperature failure strain, and can resist complicated mechanics and temperature environment of a steel bridge deck.

The invention provides a forecasting method for creep-fatigue life of a material. The method comprises the following steps: respectively performing a creep test, a fatigue test and a creep-fatigue interaction test for the material at a same test temperature; establishing a relation between the failure strain energy density wf and a non-elastic strain energy density dissipation rate of the material under a log-log coordinate according to the creep test; acquiring the fatigue damage df of the material per period according to the fatigue test; acquiring a hysteresis loop under a half-life period according to the creep-fatigue interaction test and establishing a function relation of the change of the stress Sigma (t) of the material under the half-life period within the maximum tensile strain maintaining time along with the change of time t; calculating the creep damage dc under the half-life period by combining with the hysteresis loop and based on the relation between wf and the function as shown in the specification and the relation of change of the fatigue damage df and the stress Sigma (t) along with the change of time t; and utilizing a linear accumulating damage rule to forecast the creep-fatigue life of the material under a creep-fatigue interaction. According to the method provided by the invention, the life of the material under the creep-fatigue interaction can be accurately forecasted.

The invention discloses a prediction method for the fatigue life of a complex braided structure ceramic-based composite material.The prediction method comprises the steps that the fatigue performance under a cycle number and the fiber failure percentage under the cycle number are calculated; the relationship between the fiber failure percentage and a fiber failure critical value is determined; the unit-cell scale fatigue performance is calculated to obtain the maximum strain epsilon'max under the cycle; the relationship between the maximum strain epsilon'max and the maximum failure strain epsilonmax is determined; a fatigue life curve of the material is obtained.According to the prediction method, a microscale model taking account of fibers, a base body and pores and a unit-cell multi-scale prediction model taking account of warp yarn, weft yarn and holes are presented and overcome the defects that a micromechanical method cannot be directly applied to the braded material with the complex structure, and a macroscopic phenomenological method depends on a large quantity of tests and only can achieve prediction on the fatigue life of a special material, macromechanics and micromechanics are combined, a micromechanical stress strain field of a complex braided structure is supplied, and the application range of the material is widened while the fatigue life curve of the material is precisely predicted.

The present invention relates to a polylactide blend, especially a polylactic acid / polyurethane blend and a preparation method thereof. The method provided by the invention comprises steps of: evenly mixing 70- 99wt% of a polylactic acid homopolymer and 1-30 wt% of polyester type polyurethane to obtain a mixture; and then subjecting the mixture to melt blending extrusion, casting and granulating by a twin-screw extruder at 190-220 DEG C to obtain the polylactic acid / polyurethane blend provided by the invention. The polylactic acid / polyurethane blend provided by the invention has significantly increased toughness and tensile failure strain compared with pure PLA; meanwhile, the tensile strength of the blend only decreases a little compared with that of the pure PLA.

The invention belongs to the technical field of shape memory materials, and relates to a preparation method of a shape memory composite material applied to the aerospace field. The shape memory composite material is obtained by compounding discontinuous orientation fibers and shape memory thermoplastic or thermoset resin substrates; the fibers are in a height orientation state in the composite material and the mechanical property and the retention rate of the fibers are higher than the mechanical property and the retention rate of a continuous fiber reinforced composite material; meanwhile, the fibers are discontinuous, and the average length of the fibers and the volume fraction of the fibers can be adjusted, so that the failure strain of the material reaching more than the shape memory transformation temperature can be improved through collaborative optimization, the relatively high deformation property and high folding rate are achieved, and the shape fixed rate is improved at the same time. According to the preparation method, the comprehensive optimization of the mechanical performance and the shape memory performance of the shape memory composite material can be realized, and the preparation method has wide application potential in the application field of aerospace shape memory composite materials.

A unidirectional elastomeric composite comprises a plurality of fibers generally aligned in a first direction with an elastomer filling the space between fibers. The plurality of fibers may comprise an intermediate modulus carbon fiber. Preferably, the plurality of fibers have an ultimate elongation at failure or tensile failure strain of 1% or greater, a tensile modulus between 200-400 GPa and tensile strength greater than 4 GPa. The resin or matrix may be a passive elastomer that will maintain its mechanical and chemical properties at a specific operational temperature range. Elastomers are polymers with viscoelasticity, generally having low Young's modulus and high failure strain. Methods of manufacturing the unidirectional elastomeric composite include apply the resin to fibers maintained in tension to maintain the fiber alignment.

The invention discloses a method for establishing a cement-based material fatigue failure probability and fatigue strain probability model capable of considering loading frequency. On the basis of the quasi-static loading failure strain of the cement-based material and the fatigue failure strain of the cement-based material under different loading frequencies, the cement-based material fatigue strain probability model can be conveniently and quickly obtained. On one hand, the model can predict the cement-based material and the fatigue failure probability of a structure which uses the cement-based material through fatigue strain, on the other hand, the fatigue strain of the cement-based material and the fatigue strain of the structure are calculated through the setting of the fatigue failure probability, and a new approach and a new method are provided for the service condition detection and assessment of the structure under the fatigue performance design and the fatigue loading of the corresponding structure.

The invention provides an aeolian sand subgrade construction method. The method comprises the following steps that surveying and setting out are conducted; a base layer is laid; padding is loaded and unloaded; a reinforcing layer is laid; a reinforcing layer is laid on the surface of aeolian sand, wherein the reinforcing layer comprises limestone, polypropylene fibers, loose filling and the balance coal ash; tilling is conducted, specifically, watering is conducted on the reinforcing layer, and tilling is conducted on a subgrade multiple times in the length direction; riffle watering is conducted; rolling compaction is conducted through a bulldozer; rolling compaction is conducted through a road roller; compaction detection is conducted, specifically, the compaction coefficient Kof the compacted aeolian sand is detected in a sand filling mode or a water filling mode; and the step that padding is loaded and unloading to the step that compaction detection is conducted are conducted repeatedly until the subgrade reaches a design elevation, and construction is completed. According to the aeolian sand subgrade construction method provided by the invention, the reinforcing layer is laid on the aeolian sand, the reasonable rolling compaction mode is adopted, the strength of the vibrated and compacted subgrade meets design requirements, the compressive strength is high, the failure strain resistance and tension resistance of the subgrade are greatly improved, and the stability of the subgrade is improved.

The invention belongs to the road engineering technical field, and in particular, relates to a detection method of water stability of a cold region large-grain-size asphalt mixture. The detection method comprises the steps: firstly, carrying out rolling compaction on the large-grain-size asphalt mixture into two plate block specimens, and cutting each plate block specimen into 6 small prismoid beam specimens; randomly selecting 3 specimens from the 6 small prismoid beam specimens of each plate block specimen, and forming an A group and a B group; making 6 specimens of the A group not soaked in water, making 6 specimens of the B group placed under freeze-thaw conditions, carrying out bending tests on the two groups of specimens, measuring the freeze-thaw flexural-tensile strength ratio BSR[dr] and the freeze-thaw flexural-tensile failure strain ratio FSR[dr] of the specimens, and when the average freeze-thaw flexural-tensile strength ratio BSR[dr] and the average freeze-thaw flexural-tensile failure strain ratio FSR[dr] of the two groups of specimens are both greater than or equal to 85%, considering that the water stability of the large-grain-size asphalt mixture is good. The method solves the problems of specimens molded by a traditional Marshall compaction testing method, and puts forward a new water stability testing method integrating the low temperature stability and the water stability of the asphalt mixture.

The present invention discloses a method for establishing a cement-based material fatigue failure model and a fatigue strain probability model by considering a stress level. A fatigue strain probability model of a cement-based material may be conveniently and fast obtained based on quasi-static loading failure strain of the cement-based material and fatigue failure strain at different stress levels. On one hand, the model may be used to predict, by using fatigue strain, a fatigue failure probability of the cement-based material and a structure using the cement-based material, and on the other hand, fatigue strain of the cement-based material and a structure may be calculated by setting the fatigue failure probability, to provide a new approach and a new method for a fatigue performance design of a corresponding structure and service condition detection and assessment of a fatigue loading structure.

The embodiment of the invention relates to a method and device for obtaining and verifying constitutive parameters and dynamic failure parameters. The method comprises the steps of: performing a quasi-static tensile experiment of an aluminium alloy material, and obtaining the quasi-static stress-strain curve of the aluminium alloy material; obtaining the dynamic stress-strain curve of the aluminium alloy material in different strain rates; obtaining the constitutive parameters of the aluminium alloy material by fitting according to the quasi-static stress-strain curve and the dynamic stress-strain curve; analyzing the fracture generated when the aluminium alloy material is tested, and determining the dynamic failure parameters of the aluminium alloy material; and, performing simulation calculation according to the constitutive parameters and the dynamic failure parameters, verifying the accuracy of the constitutive parameters and failure strain of the aluminium alloy material, simulating quasi-static stress-strain and dynamic stress-strain of the aluminium alloy material, then, obtaining the constitutive parameters and the dynamic failure parameters of the aluminium alloy material,and finally, verifying the constitutive parameters and the dynamic failure parameters.

The invention discloses a ZrB ₂ -SiC-C _f The invention relates to an ultra-high temperature ceramic composite material and a preparation method thereof, belonging to the field of ultra-high temperature ceramic composite materials. The present invention aims to overcome ZrB ₂ Intrinsic brittleness of base ultra-high temperature ceramics. The composite material of the present invention is composed of 30% to 60% ZrB with a particle size of 100 to 200 nm by volume fraction ₂ Powder, 15% to 30% SiC powder with a particle size of 100 to 500nm and 20% to 50% carbon fiber. Method: 1. ZrB ₂ Add the powder, SiC powder and carbon fiber into absolute ethanol, and perform ultrasonic cleaning; 2. Then ball mill and dry; Pressing and sintering, and then cooling to room temperature, ZrB ₂ -SiC-C _f Ultra-high temperature ceramic composite materials. The invention has the characteristics of low sintering temperature, small fiber damage, high damage strain of composite material, etc.; the sintering temperature of the invention is 1400-1500 DEG C. The ultra-high temperature ceramic composite material of the invention can be applied to the fields of ultra-high temperature heat-resistant structural materials and the like.

The invention discloses a prediction method for failure probability of fragile material under a high-temperature creep state. Based on the prior art, uniaxial creep failure strain is assumed to Weibull distribution in combined with the natural attribute that internal defects of the fragile material are randomly distributed, a probability density distribution curve of the uniaxial creep failure strain is acquired by using uniaxial creep experiments, a probability density function of multiaxis creep failure strain is acquired via a conversion relation between a single axis and the multiaxis creep failure strain, and thus integration is performed to acquire a failure probability computing model; on such the base, a sub-program is compiled by using a Fortran language in combination with a creep-damage constitutive equation, and thus a prediction result of the failure probability of the fragile material under the high-temperature creep state is acquired. According to the method provided by the invention, the technical problem that in the prior art, reliability prediction of the fragile material under the high-temperature creep state cannot be performed is solved, and the acquired prediction result is real, accurate, reasonable and reliable.

The invention discloses a diatomite asphalt mixture modification agent and a modified asphalt mixture. The diatomite asphalt mixture modification agent is prepared from activated diatomite and polyethylene wax, wherein the mass percent of the polyethylene wax is 2%-22%; the activated diatomite is diatomite obtained by carrying out an activation step on diatomite raw ores; the activation step comprises the following steps of crushing the diatomite raw ores, scrubbing, grading and carrying out ultrasonic vibration; the fineness of the activated diatomite is 325-800 meshes. Compared with an asphalt mixture modified by SBS (Styrene Butadiene Styrene), the dynamic stability DS of the asphalt mixture modified by the modification agent is increased by at least 30%, the water stability (residue stability) is increased by at least 3% and the low-temperature anti-cracking performance (low-temperature failure strain) is improved by at least 1%.

A FEA model, representing a structure, contains at least many finite elements for metal portion, a set of metal necking failure criteria (critical and fracture strain values defined in form of a loading path diagram) and the neck's characteristics (neck's width and a profile of strain values within the width) are received in a computer system. At each solution cycle of a time-marching simulation using the FEA model, following operations are performed at each integration point of every finite element: identifying major and minor strain values and corresponding directions from the computed strain values, calculating an equivalent metal necking failure strain value (ε_e) in the major strain direction with a formula based on corresponding critical and fracture strain values, the neck's characteristics and a characteristic dimension with respect to the major strain direction, and determining metal necking failure, which occurs when the major strain value is greater than ε_e.

A bending failure strain measurement method is used for finding out bending failure strains corresponding to different bending radiuses through using an arranged image processing system based on a CCD camera. According to the bending failure strain measurement method, on the basis of an original test system, the image processing system based on the CCD camera is additionally arranged, and bending failure strains corresponding to different bending male die radiuses are found out through cooperation of the image processing system and the original test system, thereby establishing a corresponding data set of radius-bending failure strain, and forming an index for predicting the formability of the bending deformation of a part.

The invention discloses an intensity check method of a vehicle bonding structure in a full temperature field environment. The method is characterized in that the conclusion is as follows that(1) the influence law of the environment temperature on the mechanical properties of an ISR-7008 adhesive main body shows that along with the rise of temperature, the Young modulus, the tensile strength and the failure strain of the adhesives are all on a declining curve; and (2) the test on seven different groups of temperature points on a lap joint, an inlay joint and a butt joint shows that the failurestrength of the joints gradually decreases along with the rise of the temperature, the failure strength of the joints gradually increases along with the fall of the temperature, the rigidity of the joints gradually decreases when the temperature raises from the normal temperature 25 DEG C to 80 DEG C, and the rigidity of the joints gradually increases when the temperature falls from the normal temperature 25 DEG C to -40 DEG C. The intensity check method disclosed by the invention has the advantages that the study of the performance change law of the bonded joint at different temperatures is of great significance in guiding the design of the bonding structure.