Method of single-axis cyclic test of material
FIELD: test equipment.
SUBSTANCE: invention refers to material test methods. Essence of the invention: a sample is first strained to the maximum set deformation, held in this deformation for a given time, compressed to the initial unloaded state, left in it for a given time, with further cyclic deformation with delays in each deformation stage of compression and tension, where at each tension cycle the set deformation is less than at the previous cycle, and the set deformation at each unloading cycle is larger than in the previous cycle.
EFFECT: more information on material properties from a sample test, new information represented by equilibrium stress-strain curve, dissipation loss, material softening after each tension/compression cycle, and relaxation curves together with material structure recovery curves for various deformations.
2 cl, 1 dwg
The invention relates to methods for testing of materials.
Known a method in which the cyclic stretching with increasing deformation of the sample, first along one axis, then along the second axis (see Dargazany R., Itskov M. A network evolution model for the anisotropic Mullins effect in carbon black filled rubbers // International Journal of Solids and Structures. Elsevier, 2009. V. 46. P. 2967-2977. - http://www.elsever.com/locate/ijsolstr)
A method is known in which the cyclic uniaxial stretching with increasing deformation, and at each level of deformation of the sample cycloneda many times (see J. Diani, M. Brieu, P. Gilormini Observation and modeling of the anisotropic visco-hyperelastick behavior of a rubberlike material // International Journal of Solids and Structures. Elsevier, 2006. V. 43. P. 3044-3056. - http://www.elsever.com/locate/ijsolstr)
The known method, where the sample cycloneda by complex cycle: with decreasing amplitude of the deformation in comparison with the previous loading with increasing amplitude of discharge (see Netzker Husnu S. D., M. Kaliske An andochronic plasticity formulation for filled rubber // International Journal of Solids and Structures. Elsevier, 2010. V. 47. P. 2371-2379. - http://www.elsever.com/locate/ijsolstr)
The above methods have a common drawback, namely, the failure information when testing a single sample.
The closest in technical essence and the achieved technical result of the proposed solution is a method of cyclic tests described in [Rickaby S. R., Scott N. H. A cyclic stress softening model for the Mullins effect // Intrnational Journal of Solids and Structures. Elsevier, 2013. V. 50. P. 111-120. - www.elsever.com/locate/ijsolstr] when the sample is repeatedly stretched to a predetermined deformation, and then compressed to the initial position at a constant speed.
In Fig.3 prototype presented cyclically loaded and unloaded rubber sample, which is pre-stretched from P0to P1to the point P1where the deformation λ=λmaxwhich is reached at time t. Stress relaxation occurs at time t1, then unloading from P1to P0to the initial load P0when the voltage becomes zero and the time t2. Then stretch again before deformation λ=λmax. Then again remove the load of the second cycle of deformation to the initial load P0that occurs at time t2*. This process of reducing the previous voltage when the same deformation continues and unloading during the second cycle (the process of softening of the material during subsequent cycles under the same strain). Reduce stress and possibly with further cycles of loading-unloading, i.e., t1*-t1and t2-t1* may be unequal.
The disadvantage of the prototype method is the small amount of information obtained about the properties of a material are determined by the maximum stress� in each cycle of elongation, time stretching to a predetermined deformation in each cycle and the time compression to achieve zero load. Is determined by the degree of softening of the material during each cycle of stretching and permanent deformation upon unloading in every cycle tension-compression.
The task of the invention is to obtain more information about the properties of the material when tested one sample, obtaining new data. This prevents the spread of data received due to manufacturing errors and capture various samples and save material and time trials.
The problem is solved by the features specified in the 1st paragraph of the claims, in common with the prototype, such as the method of uniaxial cyclic test material comprising uniaxial cyclic tension-compression with a constant given speed, to a predetermined deformation, and distinctive essential features, such as the first sample is stretched to a predetermined maximum strain, maintained at the specified time warp, shrink to its original condition, to withstand the specified time, then cyclically deformed with a dwell time at each step of deformation in tension and compression, the deformation in each cycle of stretch is set smaller than in the previous cycle, and the deformation at each cycle of discharge�. more than in the previous cycle. According to claim 2 of the formula of the invention, the sample at each cycle dilate at different rates of deformation. Distinctive features of the proposed method - stop and exposure time at each stage of deformation (this allows you to remove the temporal characteristic of the material) and the construction of the equilibrium curve; also the tension on each cycle at different speeds.
The above set of essential features allows to obtain the following technical result - obtaining more information about the properties of the material when tested per sample, as well as obtaining new information - the construction of the equilibrium curve stretching, dissipative losses, the softening of the material after each cycle tension-compression and relaxation curves and recovery curves of the structure of the material under different strain.
The invention is illustrated in the example and pattern. The method is carried out in the following sequence, namely by the initial deformation of the sample to a predetermined maximum deformation of the test sample, the exposure time when this strain for the process of stress relaxation, unloading of the sample at the same rate to its original status, exposure time to restore the internal structure of the material, the secondary stretching treatment�CA to the same maximum strain and exposure time for stress relaxation, compression of the sample before deformation corresponding to non-zero voltage and exposure time when this strain in the third cycle tension-compression tensile strain is set smaller than the maximum deformation at the 2nd cycle, the dwell time and unloading to the deformation, greater than it was in the second cycle, and again the exposure time to restore the structure of the material.
Further Cycling occurs before deformation, each time smaller than in the previous cycle, unloading to the deformation, greater than the previous cycle. At each given level of deformation of the specimen is subjected to exposure time. The number of cycles is not installed - the more, the more the points to construct the equilibrium curve is obtained.
The drawing shows a graph of the Cycling test, and indicate the equilibrium point of the curve. Under equilibrium curve means the curve is very slow stretching of the sample when it has all viscoelastic processes and associated stress relaxation is absent. Thus, when the deformation of the elastomeric composite of long polymer molecules slide along the surface of the carbon filler in the tension of the material. When the load is removed, the molecules return to their original state, but the process is much slower than in tension depends on the adhesion on�kernich fibers with the surface of the carbon and the mobility of molecules i.e., the temperature of the sample. This explains the presence of viscoelasticity in rubbers filled with carbon black.
The value of the viscoelasticity depends on the polymer and the degree of filling it with carbon. The unfilled elastomer viscoelasticity is missing, the higher the content, the viscoelasticity above.
To construct the equilibrium points of the curve you need to take the point of the restored structure of the material after its exposure time when unloading at each cycle and the end point of the stress relaxation after exposure time when the tensile specimen. The first point of the equilibrium curve on the x-axis is taken in the place of its intersection with the graph of discharge on the first cycle of tests.
This graph also shows the hysteresis material (dissipative) losses in tension-compression at each cycle of deformation of the compression.
In the drawing the graphs of cyclic loading where you can see the softening of the material during each cycle of deformation - the torque curve at each subsequent cycle is below the previous loading.
All charts are constructed on the computer using the data file is tested, in which there are columns with the current time, applied force, displacement.
To explore the properties of the material at different speeds on each cycle of loading is applied in different RMS�spine deformation.
An example for a cyclic test material on the proposed programme:
1. Elongation up to 100%, and wait 20 min. Speed 100%/min.
2. Return to the start position and wait 20 min. Speed 100%/min.
3. Elongation up to 100% and wait 10 min. Speed 100%/min.
4. Unloading of up to 15% and wait 10 min. Speed of 50%/min.
5. Elongation to 90% and wait 10 min. Speed of 50%/min.
6. Unloading to 22% and wait 10 min. the Speed of 20%/min.
7. Elongation of 80% and wait 10 min. the Speed of 20%/min.
8. Unloading up to 35% and wait 10 min. the Speed of 5%/min.
9. Elongation up to 70% and wait 10 min. the Speed of 5%/min.
10. Return to the starting position. The speed of 5%/min.
Thus, according to the invention is obtained the equilibrium curve stretching, dissipative losses, the softening of the material after each cycle tension-compression and relaxation curves and recovery curves of the structure of the material under different strain, and determine the dependence of the mechanical behavior of the material from warp speed.
1. Method uniaxial cyclic test material comprising uniaxial cyclic tension-compression at a given speed to a predetermined deformation, characterized in that the first sample is stretched to a predetermined maximum strain, maintained at the specified time warp, shrink to its original unloaded state, stand ass�TES the time then cyclically deformed with a dwell time at each step of deformation in tension and compression, the deformation in each cycle of stretch is set smaller than in the previous cycle, and the deformation at each unloading cycle is set higher than in the previous cycle.
2. A method according to claim 1, characterized in that the sample at each cycle dilate at different rates of deformation.
FIELD: measurement equipment.
SUBSTANCE: invention relates to measurement equipment, in particular, to devices for measurement of profile of surfaces of low-modular viscoelastic sheet materials of light industry, namely, man-made and natural leathers, etc. A device to detect profile of materials in deformed condition, comprising a base, a counting unit, a locating element, installed as capable of rotation around its axis, differing by the fact that the locating element is made in the form of a semi-cylinder with a hollow semi-cone and two limiting plates to fix a sample; the device comprises an additional counting unit fixed on the semi-cylinder, to detect bending radius of the investigated sample, arranged in parallel to the semi-cone guide, at the same time the main counting unit is made as combined, capable of displacement along the axis of rotation of the locating element and comprises a strain gauge motion sensor and a digital optical microscope.
EFFECT: device makes it possible to study hidden defects of natural leather and man-made materials, to determine variation of material relief under bending deformation.
2 cl, 1 dwg
SUBSTANCE: disclosed is a method of determining the glass-transition point of tetrazole-based polymer composite materials based, according to which the glass-transition point is determined from the change of slope of a curve of temperature versus the inverse of dielectric constant 1/ε'=f(T).
EFFECT: high accuracy and reliability of determining the glass-transition point of tetrazole-based polymer composite materials.
4 dwg, 1 tbl
SUBSTANCE: invention refers to medicine, namely to oncology, and can be used for recognising synchronous multifocal colorectal carcinoma. Substance of the invention consists in measuring preoperative blood follicle-stimulating hormone both in male and female patients suffering from colorectal carcinoma. If its concentration falls within the range of 26.01 to 60.91 IU/l in the females and of 2.71 to 5.67 IU/ml in the males, a single tumour is diagnosed in the patients, and if the hormone concentration is from 2.70 to 5.50 IU/ml in the females and from 12.88 to 52.04 IU/l in the males, the presence of synchronous colorectal new growths are stated. The method can be implemented at the preoperative stage; it is easily reproducible in the oncology hospital environment.
EFFECT: stating the presence of synchronous multifocal colorectal carcinoma.
SUBSTANCE: invention relates to field of producing carbon-carbon composite materials for various purposes, and is intended for comparative characteristic of impregnation of carbon fibre (CF) braids with melts of pitches, and can be used in improvement of technologies of producing carbon-carbon composite materials, possessing various properties, by modification or replacement of pitch binder and/or carbon fibre, for instance, in research laboratories, in particular, in carrying out laboratory work. To determine degree of impregnation of carbon fibre braids with pitches, carbon fibre braid is placed into glass tube in such a way that the end of braid protrudes from glass tube, and carbon fibres in braid are oriented along glass tube axis, with braid thickness being selected in such a way that it tightly fits glass tube, protruding end of carbon fibre braid is brought in contact with melted pitch and keep in such position, after which carbon fibre braid is extracted from tube and height of impregnation of carbon fibre braid with pitch is determined.
EFFECT: simplification and acceleration of determination are achieved.
1 ex, 3 dwg
SUBSTANCE: method involves cutting a sample for analysis and analysing its chemical composition, from which the rubber brand is determined. The sample is cut such that it has pre-decomposition zones. Chemical composition is analysed from a fracture in the sample by X-ray spectral technique on a scanning electron microscope with an energy-dispersive spectrometer. The obtained data on chemical composition of the sample are compared with chemical composition of a known rubber brand or a rubber brand used as a reference.
EFFECT: high accuracy and objectivity of determining a rubber brand.
3 ex, 1 tbl, 2 dwg
SUBSTANCE: method involves titration of a suspension with a solvent which is soluble in water and dissolves the suspended resin-like substance until reducing light scattering, which is determined either visually or using optical devices which enable to measure the amount of light passing through the liquid.
EFFECT: rapid estimation of the amount of resin-like substance suspended in water.
SUBSTANCE: apparatus has a clamp mechanism for holding material, an indenter for loading with possibility of measuring its displacement and recording information into a processor. A sensor is built into the indenter, said sensor being sensitive to the spectrum of acoustic emission generated by a sample upon change of deformation characteristics thereof. The clamp mechanism is in form of two coaxially placed cups with built-in heating elements with a controlled temperature range and a sensor for said temperature.
EFFECT: broader technological capabilities of the apparatus and high measurement accuracy.
SUBSTANCE: before testing in a heat chamber, samples of polymer materials are activated with UV radiation in the 248-365 nm wavelength range for 3-30 minutes with radiation power density of 1-15 mW/cm2. Analysis of volatile organic compounds is carried out while comparing the obtained chromatograms of gas samples collected from the heat chamber when testing samples of polymer materials with selected additives based on nanostructured bentonite powder and nanostructured bentonite powder intercalated with metal ions - magnesium (Mg2+ ), scandium (Sc3+), chromium (Cr3+), manganese (Mn2+), iron (Fe2+), cobalt (Co2+), nickel (Ni2+), copper (Cu2+), zinc (Zn2+), tin (Sn2+), cerium (Ce3+) or a mixture of bentonite powders intercalated with ions of said metals. The results of comparing chromatograms of gas samples are used to evaluate the effect of nanocomponents on the predicted sanitary-chemical properties of the designed polymer materials.
EFFECT: realisation of the present invention widens technological capabilities and increases reliability of results of evaluating the effect of modifying mineral nanocomponents on predicted sanitary-chemical properties based on release of volatile organic compounds from the designed polymer materials.
8 cl, 7 ex, 2 tbl, 4 dwg
FIELD: textile, paper.
SUBSTANCE: at the first stage the organoleptic analysis of tested samples is carried out. At the second stage the microscopic analysis of the material structure is carried out. At the third stage the chemical analysis of the tested samples is carried out by means of their treatment with an organic dissolvent selected from the group: butyl ether of acetic acid, dimethylketone, dimethylformamide, tetrahydrofuran, furfural, cyclohexanol at the ratio of sample-dissolvent equal to 1:(10-15) at the boiling temperature of the selected dissolvent for 20-30 minutes. If a sample has dissolved fully, the conclusion is made that is pertains to leather-like materials, and if a sample has not dissolved, it is identified as leather.
EFFECT: accurate and reliable recognition of leather from leather-like materials.
2 cl, 3 ex
SUBSTANCE: method involves pre-activation of surfaces of an article and a film. The article then pressed to the surface of the film made from non-light-stabilised polyethylene and then exposed to UV radiation until a brittle layer forms.
EFFECT: formation of a coating on an article, which is adhesively bonded to the surface of the article.
FIELD: testing technology.
SUBSTANCE: invention relates to construction, in particular to determining the parameters of deformation of concrete under conditions of cyclic loading to a level not exceeding the tensile strength of concrete to compression Rb and extension Rbt. Essence: securing a test concrete sample in the form of a prism in the jaws of the test stand is carried out using a centring device which provides a central application of load during loading. The force and deformation of the prism in time is registered by using the dynamometer and the strain-gauge station. The multiple static or dynamic loading is performed by rotating and short-term changing the diameter of the axis in the place of junction of the lever and the compensating element.
EFFECT: simplification of the test method, expanding the functional capabilities of the experimental determination of the static-dynamic characteristics of concrete under conditions of cyclic loading, which consists in alternating application of static and dynamic loads on the sample.
FIELD: test hardware.
SUBSTANCE: invention relates to vibrating hardware and can be used for analysis of rocks specimens and model of equivalent materials for effects of mechanical vibrations, particularly, of Relay waves. Bench comprises the bed to support with specimen gripper, loading mechanism engaged therewith and including the rotation drive. Loading mechanism consists of spinning disc with circular groove made at its end surface, two rolls opposed in said groove, two stiff parallel thrusts arranged in the plane parallel with disc spinning plane, one being coupled with appropriate roll and opposite one engaged with said gripper. Spinning disc is fitted off-centre on rotation drive shaft to adjust eccentricity while spinning drive allow rpm adjustment.
EFFECT: enlarged volume of data for analysis owing to possibility of causing the circular or elliptical oscillations inherent in Relay waves.
SUBSTANCE: invention relates to the field of construction and is intended to control the stiffness of beams, made of a material, having physically non-linear properties (in particular, reinforced concrete beams), and loaded uniformly by a distributed load. According to the declared method the reference structure is made of a physically nonlinear material for a certain type of beams in compliance with all the technological requirements for quality. The basic or the first resonant oscillation frequency ω0 is determined in the mentioned structure. The structure is loaded by a stepwise uniformly increasing distributed load, maximum deflection w0 is measured at each stage of loading, and an approximating function
EFFECT: expansion of technological capabilities of non-destructive testing method for the stiffness of beams made of a material, having physically nonlinear properties.
1 tbl, 3 dwg
FIELD: test equipment.
SUBSTANCE: proposed unit comprises bed to support rotary platform with specimen gripper, centrifugal weight to be secured at specimen end and platform drive. The latter comprises drive shaft and two rollers offset relative to shaft axis on both sides of platform rotational axis to realise frictional interaction therewith. Additionally, it incorporates the gripper drive to revolve it relative to the platform revolution.
EFFECT: enhanced performances at sign-variable flexure in two planes with centrifugal extension.
FIELD: test equipment.
SUBSTANCE: invention relates to test equipment and to strength tests. A unit includes a base and coaxially installed on it end and central grips with a common rotation axis and holes for a specimen, a rotation drive of the end grips, a pusher that is connected by one of its ends to the central grip and a loader that is connected to the other end of the pusher. The holes made in the grips have an out-of-round section and are made in compliance with the specimen cross-section.
EFFECT: increasing the volume of information by performing tests at single-cyclic and double-cyclic bending loading with the constant ratio of forces in longitudinal sections of a specimen.
2 cl, 1 dwg
FIELD: testing technology.
SUBSTANCE: invention relates to the testing technology, the study of samples and products for strength under cyclic loading. The unit comprises a housing, the platform mounted on it with the rotary drive, the additional platforms located on it, a grip for the sample located on one of the additional platforms. The additional platforms are mounted successively one on another and are provided with rotary drives, at that the number of platforms is predetermined by the number of loading cycles.
EFFECT: enhancing the technological capabilities by providing multicyclic loading at the independent regulation of the quantity and parameters of the cycles during the test.
SUBSTANCE: invention relates to construction, namely to mechanical tests of materials, in particular to testing methods for building constructions, and may be used for testing the bending of beam constructions. Essence: the controlled cyclic load is applied to the sample and by the loading or unloading rate, and its magnitude, the selected parameters of loading are maintained at the predetermined time interval. Range and place of application of loads is regulated by the loading device and power device, and the strength and deformation parameters of the test structure are measured in the given time interval. Device contains the supports for the placement of the test specimen fixed in the reinforced floor, loading device with the power device. Loading device is designed in the form of, at least, one lever and the power device is designed in the form of cargo tank, which is positioned on each lever of loading device and designed with possibility to fill it with liquid.
EFFECT: possibility to evaluate the strength and operating parameters of flexible constructions in real modes of load measurement during operation after the complete and partial unloading.
5 cl, 2 dwg
FIELD: testing technology.
SUBSTANCE: unit comprises a base, a turntable platform mounted on it, grip of the sample mounted on the platform, two centrifugal weights designed to secure at the ends of the sample, rotary drive of the platform, comprising a shaft with the rotary drive, a pair of rollers mounted eccentrically on opposite sides of the rotation axis of the platform and designed for frictional interaction with it, one of which is mounted on the shaft. The unit is additionally provided with a second shaft mounted coaxially with the first shaft and the rotary drive of the second shaft, at that the second roller is mounted on the second shaft.
EFFECT: enhanced functionality of the unit through providing tests both at alternating bending in two planes, and at alternating bending in one plane and constant bending in a second plane, as well as at circular bending and circular bending with stretching.
FIELD: testing equipment.
SUBSTANCE: centrifugal plant comprises a base, a rotation platform installed on it, sample grips radially arranged on the platform, one of which is connected to the platform, a centrifugal weight connected to the second grip, and two coaxially installed rotation drives kinematically connected to the platform. The centrifugal plant is additionally equipped with two electromagnetic fixators for connection of the platform with the appropriate rotation drives.
EFFECT: increased volume of information in research of energy exchange during deformation and damage of solid bodies by provision of tests under stepped variations of axial load with development of pulse bending loads at moments of stepped variations of axial load, which are proportionate to values of steps of axial load variation and having identical or different directions of bending.
SUBSTANCE: device comprises a frame, lifting table, capable to change the height, positioning node of test beam, load node of test beam made with possibility to apply cyclic dynamic load and possibility to measure displacements and loading force, comprising rod and slide mechanism. Positioning nod of the test beam comprises clamping jaws mounted on the ends of the test beam parallel to the transverse symmetry axis of the frame and intermediate elastic foundation made as a container filled with model soil with the possibility of tight contact with the place of test beam facing to it. Loading element of load node of the test beam is designed with the possibility of its positioning in the middle of the test beam.
EFFECT: increase of reliability of assessment of asphalt concrete fatigue strength parameters under cyclic dynamic impacts, reduction of the structure materials consumption.
5 cl, 2 dwg
FIELD: testing engineering.
SUBSTANCE: bench comprises asynchronous electric motor and balancing machine interconnected through the shaft to be tested, control unit, and resonance pickup mounted on the shaft and connected with the input of the control unit. The bench is provided with the frequency converter, DAC unit, thyristor controller of voltage, and inverter. The first output of the control unit is connected with the frequency converter connected to the circuit for power supply to the asynchronous motor. The second output of the control unit is connected in series with the DAC unit and thyristor voltage controller connected with the exciting winding of the balancing machine. The circuit of the armature of the balancing machine is connected to the inverter.
EFFECT: enhanced reliability of testing.