CN104316390B - Method for measuring brittle fracture impact remission of descending branch of brittle test piece - Google Patents

Abstract

The invention discloses a method for remission of the instantaneous brittle fracture impact during measurement of a descending branch of a brittle test piece. The method comprises the following steps: immediately reversely loading the test piece when detecting that the test piece enters an instantaneous brittle fracture critical state of the descending branch to ensure that a loading cavity originally connected with a high-pressure oil inlet pipe is switched into a low-pressure oil returning pipe so as to enable the pressure rapidly to decline; meanwhile, changing an original oil returning cavity into the loading cavity so as to enable oil in the loading cavity to drag a piston and prevent the piston from inertially sliding on the one hand, and quicken the pressure relief of the original loading cavity on the other hand; meanwhile, counteracting the releasing of elastic energy stored by the loading equipment and recovering of elastic deformation of the loading equipment by reverse recovering of a piston rod until the pressure of the original loading cavity is less than the bearing capacity of the test piece, thus realizing balance and recovering the normal control; and repeating until a test stop condition test piece is met. According to the method, a mechanical structure and control system hardware do not require to be added, and thus the cost is saved; an additional damping force is overlapped on the bearing capacity of the test piece, and measurement precision and data processing difficulty are not affected. Real-time proper response can be made for any tonnage of brittle fracture.

Description

The measurement of fragility test specimen descending branch and brittle failure impact alleviation method

Technical field

The present invention relates to a kind of fragility test specimen descending branch measurement and brittle failure impact alleviation method, belong to large scale civil engineering knot Structure experimental technique field.

Background technology

In large scale civil engineering structure experimental technique field, the descending branch measurement of fragility test specimen such as plain concrete columns etc. is Educational circles's difficult problem, slowing down the impact failure that during brittle break, transient energy release causes is also educational circles's difficult problem.

The control system of application and control algolithm at present, due to unpredictable test specimen state, enters in fragility test specimen and declines Duan Shi, because test specimen breakdown speed is exceedingly fast, the bearing capacity that system had not also declined to a upper moment responds, the holding of test specimen Load power has become lower.Due to system the discharge rate of load is less than and bearing capacity decrease speed, Unloading Control adjusts It is later than depression of bearing force, the load out control of system lags behind the change of test specimen bearing capacity state all the time.Along with loading equipemtn institute Storage elasticity can abrupt release Overlay so that test specimen occur moment collapse broken.

One of solution commonly used at present is enlargement discharge, shortens system delay, but this needs more powerful motor And oil pump, the cost of thicker oil pipe, more accurate components and parts and Geng Gao.

Another method is exactly damping unit in parallel and between test specimen, and this increases installation, measurement work and cost first；Its The secondary brittle failure point tonnage due to different test specimens is different, and damping unit can only could play protection in the range of its own bearing capacity and make With；Because damper exists a certain degree of non-linear, increased the difficulty of data processing, measurement result accuracy has also dropped Low.

Content of the invention

Object of the present invention is to provide a kind of fragility test specimen descending branch measurement and brittle failure impact alleviation method, the method And device not only overcomes the limitation of traditional measurement method, reduce the difficulty of later data process simultaneously.

For achieving the above object, the technical solution used in the present invention is a kind of fragility test specimen descending branch measurement and brittle failure impact Alleviation method, the state of described fragility test specimen carries out real-time monitoring by force snesor, displacement transducer, and test specimen is arranged on sensing Between device and ground.

Detect test specimen enter descending branch brittle failure critical condition when, that is, under displacement control condition test specimen bearing capacity reduce, Displacement deformation increases and Bit andits control precision is overproof, now Opposite side loading immediately, makes originally to connect the LOADED CAVITY of high pressure oil inlet pipe It is switched to low-pressure oil return pipe, allow pressure rapid decay；Simultaneously original oil back chamber becomes LOADED CAVITY, and the fluid one side in chamber is dragged Live piston, stop its inertia from gliding, on the other hand accelerate the release of original LOADED CAVITY, simultaneously the elasticity energy stored by loading equipemtn The recovery of release and loading equipemtn elastic deformation also to be offset by the reverse recovery of piston rod, until the pressure of former LOADED CAVITY is less than The bearing capacity of test specimen re-fetches balance and recovers normal and control；So circulation is until meeting test stop condition test specimen：Hold Load power F₂Stop force threshold P less than default test_FOr test piece deformation is more than default test and stops displacement threshold value P_L.

The present invention enters the detection of descending branch brittle failure critical condition according to being to test specimen：When position control order is constant, test specimen holds Load power reduces, test specimen displacement deformation increases, displacement of targets and displacement command error exceed control accuracy institute allowable error.

Compared with prior art, the present invention has the advantages that.

1st, mechanical construction and control system hardware need not be increased, cost-effective.

2nd, extra damping force is not superimposed to test specimen bearing capacity, does not affect certainty of measurement data intractability.

3rd, the appropriateness response in real time that the brittle failure of any tonnage can be made.

Brief description

The flow chart of Fig. 1 the inventive method.

Fig. 2 is the embodiment loading figure of this device.

Fig. 3 is the embodiment unloading figure of this device.

In figure：1st, high pressure oil inlet pipe, 2, electrohydraulic servo valve, 3, epicoele oil pipe, 4, oil cylinder, 5, epicoele, 6, piston, 7, piston Bar, 8, cavity of resorption, 9, force snesor, 10, displacement transducer, 11, lower cavity oil pipe, 12, low-pressure oil return pipe, 13, controller, 14, examination Part.

ΔL_LLoad (piston, piston rod are descending) amplification for displacement；

ΔU_LUnload (piston, piston rod are descending) amplification for displacement；

P_FFor default test stop condition power threshold values；

P_LFor default test stop condition displacement threshold values；

δ_LFor system control accuracy.

Specific embodiment

Below in conjunction with drawings and Examples, the present invention is described in further detail.

As shown in Figure 1-2, a kind of fragility test specimen descending branch measurement and brittle failure impact alleviation method, the shape of described fragility test specimen State passes through force snesor 9, displacement transducer 10 carries out real-time monitoring, and described test specimen 14 is arranged between sensor 9 and ground.

When test specimen 14 entrance descending branch brittle failure critical condition is detected, that is, under displacement control condition, test specimen bearing capacity subtracts Little, displacement deformation increases and Bit andits control precision is overproof, now Opposite side loading immediately, make originally to connect high pressure oil inlet pipe 1 plus Carry chamber and be switched to low-pressure oil return pipe 12, allow pressure rapid decay；Simultaneously original oil back chamber becomes LOADED CAVITY, the fluid one in chamber Aspect holds piston 6, stops its inertia from gliding, on the other hand accelerates the release of original LOADED CAVITY, simultaneously stored by loading equipemtn Elasticity can discharge and the recovery of loading equipemtn elastic deformation also to be offset by the reverse recovery of piston rod 7, until former LOADED CAVITY Pressure be less than the bearing capacity of test specimen 14 and re-fetch balance and recover normal and control；So circulation stops bar until meeting test Part test specimen：I.e. bearing capacity F₂Stop force threshold P less than default test_FOr test piece deformation is more than default test and stops displacement threshold value P_L.

The present invention enters the detection of descending branch brittle failure critical condition according to being to test specimen：When position control order is constant, test specimen holds Load power reduces, test specimen displacement deformation increases, displacement of targets and displacement command error exceed control accuracy institute allowable error.

In Fig. 2-3, Real-time Collection displacement transducer 10 and force snesor 9 data under controller 13 prosecutor formula in place, and root Reduce according to bearing capacity, displacement deformation increases and the overproof test specimen brittle failure state that carries out of Bit andits control precision judges, once controller 13 Judge that current test specimen is in brittle failure state, just control electrohydraulic servo valve 2 execution switch operation, high pressure oil inlet pipe 1 is connected to cavity of resorption Oil pipe 11, injects hydraulic oil to the cavity of resorption 8 of oil cylinder 4, low-pressure oil return pipe 12 is connected to epicoele oil pipe 3 simultaneously, allows the epicoele of oil cylinder 4 Fluid release in 5 simultaneously flows back, such piston 6 drive piston rod 7 counter motion to test specimen unloading and release device storage bullet Performance, continues normal load after test specimen departs from brittle failure state.

ΔL_LIt is the amplification of each displacement loading command being manually set, that is, the displacement amplification that oil cylinder moves down, That is, displacement command increases Δ L every time on the basis of original_L.

ΔU_LIt is the amplification of each displacement unloading order being manually set, that is, the displacement amplification that oil cylinder moves up, That is, displacement command reduces Δ U every time on the basis of original_L.

P_LIt is the default test stop condition displacement threshold value being manually set that is to say, that the deformation working as test specimen is more than P_L, that The deflection of test specimen meets test requirements document.

δ_LIt is the system control accuracy being manually set, is also parallel algorithm band, when the absolute value measuring value difference twice More than δ_L, illustrate to be currently at runaway condition.

S1 measures current test specimen bearing capacity F first, is assigned to F₁, measure displacement L, be assigned to L₁；

S2 reads current displacement controlled loading order (hereinafter referred to as displacement command) C_L, C_LIt is that controller test specimen carries currently Control the operating value of electro-hydraulic servo valve events；

S3 measures current power F, is assigned to F₂, measure displacement L, be assigned to L₂；

Current power or displacement meet stop condition, and that is, power drops to threshold values P_FBelow or deformation reach threshold values P_LMore than, test Terminate；

S4 otherwise judges whether test specimen is in brittle failure critical condition；

S5.1 is if it is, be assigned to F respectively current power and displacement₁And L₁, then deduct displacement with current displacement command and unload Carry amplification, that is, on the basis of current position, carry piston and piston rod to opposite direction.Now, controller controls servo valve commutation, former The LOADED CAVITY (epicoele) come is switched to low-pressure oil return pipe by high pressure oil inlet pipe, and unloading chamber (cavity of resorption) originally simultaneously is changed into LOADED CAVITY and cuts Change to high pressure oil inlet pipe, realize the rapid unloading of epicoele and the release of elasticity energy；

S5.2, if not brittle failure critical condition, is assigned to F respectively current power and displacement₁And L₁, then in former order base Displacement is increased on plinth and loads amplification, continue test；

S6 measures current power F, is assigned to F₂, measure displacement L, be assigned to L₂, continue this circulation；

S7 is until off-test.

Claims (3)

1. a kind of measurement of fragility test specimen descending branch and brittle failure impact alleviation method it is characterised in that：The state of described fragility test specimen Real-time monitoring is carried out by force snesor (9), displacement transducer (10), test specimen (14) be arranged on force snesor (9) and ground it Between；

Detect test specimen (14) enter descending branch brittle failure critical condition when, that is, under displacement control condition test specimen bearing capacity reduce, Displacement deformation increases and Bit andits control precision is overproof, now Opposite side loading immediately, makes originally to connect the loading of high pressure oil inlet pipe (1) Chamber is switched to low-pressure oil return pipe (12), allows pressure rapid decay；Simultaneously original oil back chamber becomes LOADED CAVITY, the fluid one in chamber Aspect holds piston (6), stops its inertia from gliding, on the other hand accelerates the release of original LOADED CAVITY, loading equipemtn is stored up simultaneously The elasticity deposited can discharge and the recovery of loading equipemtn elastic deformation also to be offset by the reverse recovery of piston rod (7), adds until former The pressure carrying chamber re-fetches balance less than the bearing capacity of test specimen (14) and recovers normal and control；So circulation is until meeting test Stop condition is test specimen bearing capacity F₂Stop force threshold P less than default test_FOr test piece deformation is more than default test and stops displacement Threshold value P_L；

When the detection that test specimen is entered with descending branch brittle failure critical condition is according to being that position control order is constant, test specimen (14) bearing capacity drops Low, test specimen displacement deformation increases, displacement of targets and displacement command error exceed control accuracy institute allowable error.

2. a kind of fragility test specimen descending branch measurement according to claim 1 and brittle failure impact alleviation method it is characterised in that： Real-time Collection displacement transducer (10) and force snesor (9) data under controller (13) prosecutor formula in place, and subtracted according to bearing capacity Little, displacement deformation increases and the overproof test specimen brittle failure state that carries out of Bit andits control precision judges, once controller (13) judges at present Test specimen is in brittle failure state, just controls electrohydraulic servo valve (2) execution switch operation, high pressure oil inlet pipe (1) is connected to lower cavity oil pipe (11), inject hydraulic oil to the cavity of resorption (8) of oil cylinder (4), low-pressure oil return pipe (12) is connected to epicoele oil pipe (3) simultaneously, allows oil cylinder (4) the fluid release in epicoele (5) simultaneously flows back, and such piston (6) drives piston rod (7) counter motion to unload to test specimen and release Put the elasticity energy of equipment storage, after test specimen departs from brittle failure state, continue normal load；

ΔL_LIt is the amplification of each displacement loading command being manually set, that is, the displacement amplification that oil cylinder moves down, that is, Say, displacement command increases Δ L every time on the basis of original_L；

ΔU_LIt is the amplification of each displacement unloading order being manually set, that is, the displacement amplification that oil cylinder moves up, that is, Say, displacement command reduces Δ U every time on the basis of original_L；

P_LIt is that the default test being manually set stops displacement threshold value that is to say, that the deformation working as test specimen is more than P_L, then test specimen Deflection meets test requirements document；

δ_LIt is the system control accuracy being manually set, is also parallel algorithm band, when the absolute value measuring value difference twice is more than δ_L, illustrate to be currently at runaway condition.

3. a kind of fragility test specimen descending branch measurement according to claim 1 and brittle failure impact alleviation method it is characterised in that： The implementation process of the method is as follows,

S1 measures current test specimen bearing capacity F first, is assigned to F₁, measure displacement L, be assigned to L₁；

S2 reads current displacement controlled loading order C_L, C_LIt is that controller test specimen carries the current behaviour controlling electro-hydraulic servo valve events Work value；

S3 measures current power F, is assigned to F₂, measure displacement L, be assigned to L₂；

Current power or displacement meet stop condition, and that is, power drops to threshold values P_FBelow or deformation reach threshold values P_LMore than, test knot Bundle；

S4 otherwise judges whether test specimen is in brittle failure critical condition；

S5.1 is if it is, be assigned to F respectively current power and displacement₁And L₁, then deduct displacement unloading with current displacement command and increase Width, that is, on the basis of current position, carries piston and piston rod to opposite direction；Now, controller controls servo valve commutation, originally LOADED CAVITY is switched to low-pressure oil return pipe by high pressure oil inlet pipe, and unloading chamber is changed into LOADED CAVITY and is switched to high pressure oil inlet pipe originally simultaneously, Realize the rapid unloading of epicoele and the release of elasticity energy；

S5.2, if not brittle failure critical condition, is assigned to F respectively current power and displacement₁And L₁, then on the basis of former order Increase displacement and load amplification, continue test；

S6 measures current power F, is assigned to F₂, measure displacement L, be assigned to L₂, continue this circulation；

S7 is until off-test.