CN2399720Y

CN2399720Y - Pitch mixed material low temp. low frequency fatigue testing machine

Info

Publication number: CN2399720Y
Application number: CN 99249808
Authority: CN
Inventors: 应荣华; 郑健龙; 林魁壁
Original assignee: HIGHWAY ENGINEERING TEST DETECTION CENTER CHANGSHA JIAOTONG COLLEGE
Current assignee: HIGHWAY ENGINEERING TEST DETECTION CENTER CHANGSHA JIAOTONG COLLEGE
Priority date: 1999-12-01
Filing date: 1999-12-01
Publication date: 2000-10-04
Anticipated expiration: 2009-12-01

Abstract

The utility model relates to a pitch mixed material low-temperature low-frequency fatigue tester. A movable force application base which uses a ball to slide is hinged with a piston of an inner-outer double-layer oil cylinder through a lever, and the piston and a fixed force application base are arranged on the same working platform. A test piece is connected between the two force application bases, and with an electric heater to heat the oil in the cylinder, the hot oil expands to push the piston in the oil cylinder to apply pulling force to the test piece. The loading period is low, which reaches once-twice per hour, even once every several hours to one every a plurality of tens of hours. An isoperibol box is arranged on the tester, and the isoperibol box can control and maintain a certain constant-temperature value in the range of-25 DEG-+35 DEG. The precision is 0.5 DEG. The utility model has the advantages that the slow load of the low-temperature low-frequency one-way pulling force can be achieved under the condition that the constant temperature is maintained and test results are simulated to be close to actual working conditions.

Description

Asphalt low temperature and low frequency fatigue tester

The utility model relates to a kind of ground surface material---the fatigue tester that the fatigue tester of asphalt, particularly low temperature and low frequency load.

The testing machine of existing test asphalt fatigue behaviour has the repeated flex testing machine, rotary semi-girder fatigue tester and servo-hydraulic closed-loop control system device, and they have the problem of 3 different aspects respectively:

1. what test specimen bore on testing machine is moment of flexure, or moment of flexure and shearing combined action, and actual pavement asphalt material production be unidirectional draw, the compressive stress strain.

2. loading frequency height, per minute 1～45 time, 60 times is high to 1000 times.

3. temperature control is poor, is difficult to meet the requirements of temperature.

Because it is slowly mostly that long-term and diurnal temperature changes, the load of drawing that the road surface heat expansion produces is slow gradual change, actual pitch mixing road surface is to be in the low frequency stress state, and generally speaking, loading frequency is per hour 1～2 time, in addition several hrs to ten a few hours load change once low frequency loading fatigue test result and the fatigue test results of the conventional test frequency (10Hz) of per minute 600 times be diverse; And the reflection crack of bituminous pavement is because the double action of temperature and load causes, and temperature plays a major role, and temperature does not reach requirement, and is very big to the test findings influence.

The purpose of this utility model is to design the unidirectional pulling force that bears of a kind of test specimen, and the slow liquid of low frequency is slow steadily to load, Controllable Temperature, and high low temperature all reaches the pavement asphalt compound fatigue tester of testing requirements.

Technical solution of the present utility model is a kind of asphalt low temperature and low frequency fatigue tester, by last installation test specimen on the workbench test specimen being executed the force application apparatus that carries constitutes, force application apparatus is slow curtain puller system, it is an inside and outside double-deck oil cylinder that sealing is oil-filled, in the outer oil cylinder electric heater is arranged, inner cylinder is equipped with piston, piston rod stretches out outside the cylinder, rod end nationality lever hinge connection activity application of force seat, test specimen two ends respectively the mat jockey be installed in workbench on activity application of force seat and fixedly application of force seat connect; Testing machine is equipped with the oil cylinder oil-temperature control device; Testing machine has the constant temperature oven of temperature adjustable, and constant temperature oven is divided into chamber and gives incubator, and test specimen places the isoperibol case.

Testing machine and machine external pelivimetry instrument are used in combination, and the test specimen that is loaded on the testing machine attaches sensor, and sensor and measuring instrument electrically connect, and the electric signal that sensor produces is received the power strainmeter of measuring instrument, receives display screen and printer more respectively.

Description of drawings is as follows:

Fig. 1 is this practical new asphalt low temperature and low frequency fatigue tester structural representation

A kind of asphalt low temperature and low frequency fatigue tester, constitute by test specimen being installed on the workbench and test specimen being executed the force application apparatus that carries, force application apparatus is slow puller system, in its sealing is oil-filled, outer double-deck oil cylinder, referring to accompanying drawing 1, electric heater [8] is housed in the outer oil cylinder [7], outer oil cylinder [7] nationality connecting pipe [29] connects with oil pump [28] and oil tank [26] successively and is communicated with, dress piston [4] in the inner cylinder [5], piston rod [2] stretches out outside the cylinder, rod end mat lever [1] hinge connection activity application of force seat [9], lever [1] one end and piston rod [2] are hinged, other end location is articulated in the connection seat [25] on the frame, activity application of force seat [9] connects with lever [1] middle part hinge, activity application of force seat [9] mat ball [11] connects with workbench [12] slippage, test specimen [14] two ends respectively mat jockeies [10] and be installed in workbench [12] on activity application of force seat [9] and fixedly application of force seat [16] connect; Test specimen [14] is gone up and is attached stress, strain transducer, and the measuring instrument of sensor outside electric bridge box and testing machine electrically connects, and is connected to the power strainmeter of measuring instrument, is connected to display screen and printer more respectively; Testing machine has the isoperibol case of temperature adjustable, be divided into chamber [23] and preheating cabinet [22], preheating cabinet [22] places chamber [23] below, both have hole link, the isoperibol case is equipped with electrothermal quartz tube [13] heating, place top chamber [23], cooling tube [21] is housed in the below preheating cabinet [22] is communicated with refrigeration with refrigerator [20] connection; Ring temperature control device control constant temperature also is housed, the ring temperature control device is made up of temperature controller and temperature sensor, high and low temperature sensor [15] [17] is loaded on respectively in the top chamber [23], pyrostat [17] and temperature controller A[18] electrically connect temperature controller A[18] switch series is connected in the circuit of electrothermal quartz tube [13]; Low-temperature sensor [15] and temperature controller B[19] electrically connect temperature controller B[19] switch series be connected in the circuit of refrigerator [20]; Slowly the oil cylinder of force application apparatus is equipped with oil-temperature control device, it is the temperature sensor [6] and temperature controller C[27 that is loaded on the outer cylinder wall] electrically connect, temperature controller C[27] switch series be connected in the circuit of motor M of oil pump [28], be loaded on workbench [12] and go up the position switch [24] of close movable force application apparatus [9] one ends, its contact K is serially connected in electric heater [8] circuit of outer oil cylinder [7]; Temperature controller A, B, C are prior art, and product is bought in market.

Principle of work of the present utility model is: when electric heater [8] energising heating, oily temperature rise in the outer oil cylinder [7], oil-filled expanded by heating in the annular seal space of inner cylinder [5] right-hand member casing wall and piston [4], promote piston [4] to left movement, by piston rod [2] mat lever [1], activity application of force seat [9], connect and draw anchor clamps [10] that test specimen [14] is applied pulling force, along with the oil temperature constantly raises, pulling force strengthens gradually, because the controlled slow rising of oil temperature, pulling force also is slow increasing; When oily temperature rise to certain numerical value, in the time of for example about 180 ℃, corresponding certain numerical value that is increased to of pressure, oil temperature sensor this moment [6] sends electric signal and gives temperature controller [27], temperature controller C[27] switch C ₁, C ₂, action; Switch C ₁Connect the circuit of oil pump [28]; While switch C ₂Cut off the middle oil heating of circuit failure of oil feed cylinder [7] of electric heater [8], oil pump [28] then injects oil cylinder [7] with the cold oil in the oil tank [26], make in the cylinder oil cooling but, the oil temperature reduces gradually, piston [4] slowly resilience to the right under back-moving spring [3] effect, and drive activity application of force seat [9] resets to the right, test specimen [14] is removed pulling force gradually, the oil temperature drop is during to normal temperature, and activity application of force seat [9] is touched limit switch [24], its switch contact K ₁Connect electric heater [8] circuit and give oil heating in the cylinder again, and its K switch of while ₂Then cut off oil pump [28] circuit, stop to pump into cold oil to oil cylinder, circulation is so repeatedly slowly applied unidirectional pulling force for test specimen [14] low frequency and tests, execute the carrier frequency rate and can hang down and reach per hour 1～2 time, a few hours once, and even tens of hours once.

When test specimen [14] bore the slow loading tensile test of low frequency, refrigeratory in the isoperibol case or electrothermal quartz tube [13] can be worked respectively according to testing requirements.Make the isoperibol case keep some high temperature values or low-temperature values, when carrying out low-temperature test, refrigeratory work is by temperature controller B[19] control refrigerator [20] work jointly with low-temperature sensor [15], by cooling tube [21] refrigeration, make in the isoperibol case temperature maintenance in some low-temperature values; When test specimen carried out hot test, electrothermal quartz tube [13] energising heating was by temperature controller A[18] control electrothermal quartz tube [13] work jointly with pyrostat [17], make the some high temperature values of temperature maintenance in the constant temperature oven; The high and low temperature range of control is at+35 ℃～25 ℃, and control accuracy is 0.5 ℃.

Before the specimen test, place pre-incubator to place a period of time earlier, make the interior temperature of test specimen surface and body even, test then.

Testing machine and machine external pelivimetry instrument are used in combination, and the test specimen that is loaded on the testing machine attaches sensor, and sensor and measuring instrument connect, and the electric signal that sensor produces is received the power strainmeter of measurement, receives display screen and printer more respectively.

The utility model has the advantages that: the unidirectional pulling force of loading force; Loading frequency is low, can realize per hour 1～2 time, even A few hours～once slowly low frequency loading in tens of hours; Can carry out low frequency load test under the low temperature, and test temperature can be at-25 ℃ Keep some steady state values in～+ 35 ℃ of scopes, precision can reach 0.5 ℃; Pre-incubator is arranged, and test specimen is tested front elder generation in advance Place in the incubator, make the inside and outside temperature one of test specimen even. Therefore the utility model asphalt mixture fatigue testing function simulation The closing to reality operating position is tested the fatigue behaviour of asphalt and temperature, load, particularly low temperature and low better The factors such as frequency load mode are to the impact of fatigue performance of asphalt mixture.

Claims

1. an asphalt low temperature and low frequency fatigue tester constitutes by test specimen being installed on the workbench and test specimen being executed the force application apparatus that carries, and it is characterized in that:

(1) force application apparatus is slow puller system, it is an inside and outside double-deck oil cylinder that sealing is oil-filled, in the outer oil cylinder electric heater is arranged, inner cylinder is equipped with piston, piston rod stretches out outside the cylinder, rod end nationality lever hinge connection activity application of force seat, test specimen two ends respectively the mat jockey be installed in workbench on activity application of force seat and fixedly application of force seat connect;

(2) testing machine is equipped with the oil cylinder oil-temperature control device;

(3) testing machine has the isoperibol case of temperature adjustable, is divided into chamber and gives incubator, and test specimen places the isoperibol case.

2. asphalt low temperature and low frequency fatigue tester according to claim 1 is characterized in that the isoperibol case of its temperature adjustable electrothermal quartz tube being housed, and cooling tube connects with refrigerator and is communicated with chiller, temperature regulating device.

3. according to claim 1 and 2 described asphalt low temperature and low frequency fatigue testers, the ring temperature control device that it is characterized in that the isoperibol case is: the high and low temperature sensor is loaded on respectively in the chamber of top, pyrostat and temperature controller A electrically connect, temperature control A switch series is connected in the electrothermal quartz tube circuit, low-temperature sensor and temperature controller B electrically connect, and the switch series of temperature control B is connected in the circuit of refrigerator.

4. asphalt low temperature and low frequency fatigue tester according to claim 1, it is characterized in that its oil cylinder oil-temperature control device is: the oil temperature sensor and the temperature controller C that are loaded on the outer cylinder wall electrically connect, and the switch series of temperature control C is connected in the circuit of oil pump motor M; Be loaded on the position switch of close movable force application apparatus one end on the workbench, its contact K is serially connected in the electric heater circuit of outer oil cylinder.