CN106353186A - Test method for determining recovery coefficient in metal material contact-impact - Google Patents

Abstract

The invention discloses a test method for determining a recovery coefficient in metal material contact-impact. The test method includes the steps of S1, preparing test materials including a metal ball, a metal plate, a speed sensor and an acquisition card; S2, releasing the metal ball during the test to enable the metal ball to fall from a high position keeping a distance of H away from the metal plate, and enabling the speed sensor to acquire an acceleration value and an impact time value of the metal ball impacting the metal plate every time in a process that the metal ball impacts the metal plate at the first time and finally stops on the metal plate, wherein the acceleration value acquired at the ith time is recorded as ai, and the time value corresponding to the ai is recorded as ti; using the acquisition card for acquiring the acceleration values and the time values; S3, processing test data, namely S31, making a curve graph about acceleration changing along with time according to the acceleration values and the time values corresponding to the acceleration values; S32, sequentially obtaining deltati, Tn and T2n; S33, obtaining the recovery coefficient. The test method for determining the recovery coefficient in metal material contact-impact has the advantages that the test method is easy to operate and capable of obtaining the precise impact recovery coefficient by testing the acceleration changing along with the time in the metal material contact-impact process, so that measurement precision is improved.

Description

A kind of test method determining recovery coefficient in metal material contact-impact

Technical field

The present invention relates to metal material experimental technique field, determine recovery in metal material contact-impact particularly to a kind of The test method of coefficient.

Background technology

In kinematic analysis of mechanisms, two components contacted by point or linear contact lay and the higher pair that constitutes belongs to basic exercise pair One.In order to accurately calculate in higher pair between two components in the abrasion leading to of relatively sliding, generally require to obtain between two components The impact force occurring in contact and its material deformation information, in order to obtain impact force and bag in the relation of material deformation The hysteresis effect containing damping is it must be determined that collision recovery coefficient between two kinds of metal materials.

Different metal material contact-impact, its collision recovery coefficient is also different, and existing measuring method is typically passed through Accurate measurement collides the velocity variations in front and back of material, to obtain collision recovery coefficient.And accurate detection speed is typically difficult to. Additionally, the jumping height change before and after measurement collision material impacts, it is also a kind of effective metering system, but bullet after material impacts The height change rising is dynamic, and accurately its maximum height value after upspringing of acquisition is also relatively difficult, have impact on collision restorer The computational solution precision of number.Once this collision recovery coefficient can accurately be obtained, then can obtain in higher pair and touch between two components Hit the damping hysteresis effect in power and metal material juxtaposition metamorphose, thus being conducive to calculating the abrasion longevity between two components in higher pair Life.

As shown in figure 1, material 1 is relative sliding along common tangent direction in contact-impact with material 2 (being metal material) Dynamic, its relative sliding velocity is v₁, f_nAnd f_n' it is normal direction impact force in opposite direction equal in magnitude.This impact force and deflection Shown in relation such as formula (1):

$f_n={\mathrm{k\δ}}^n+d\stackrel{\·}{\mathrm{\δ}}---\left(1\right)$

Wherein, the Section 1 in formula (1) represents stiffness term, and Section 2 represents the delayed item of damping, and k is stiffness coefficient, and δ is to become Shape amount,For deformation velocity, n is the power exponent of juxtaposition metamorphose, and d is damped coefficient, shown in concrete form such as formula (2):

$\mathrm{\μ}=\frac{3k(1-e^2)}{4{\stackrel{\·}{\mathrm{\δ}}}^{(-)}}---\left(2\right)$

Be can be seen that to obtain damped coefficient d it is necessary to obtain the collision recovery coefficient e of material by formula (2).In view of This, the present inventor develops a kind of assay device that can fast and effeciently determine recovery coefficient in metal material contact-impact.

Content of the invention

It is an object of the invention to provide a kind of test method determining recovery coefficient in metal material contact-impact, its knot Structure is simple to operation, by the time change during test metal material contact-impact, you can obtains accurate collision and recovers Coefficient, compares traditional tachometric survey, dynamic height measurement is easier, certainty of measurement is also higher.

To achieve these goals, technical scheme is as follows:

A kind of test method determining recovery coefficient in metal material contact-impact, comprises the following steps:

S1. test prepares

Prepare test material: metal ball, metallic plate, velocity sensor and capture card, by velocity sensor with capture card even Connect；

S2. process of the test

Release metal ball so as to from falling apart from the eminence of h with metallic plate, collide metallic plate for the first time in metal ball until During stopping at metallic plate, velocity sensor obtains the metal ball accekeration of collision rift and collision every time on a metal plate Time value, common m time, the acceleration of note i ＆ lt collection is a_i, a_iCorresponding time value t_i, 1≤i≤m；Capture card gathers this acceleration Angle value and time value；

S3 experimental data processing, comprises the following steps:

S31. the time value according to corresponding to accekeration and acceleration makes acceleration time history plot；

S32. observe the peak value corresponding time t of described curve chart_i, obtain the i-th -1 time collision and i ＆ lt collision successively Time interval is δ t_i, collide the total time t of (n+1)th collision the 1st time_n, collide the 1st time the 2n+2 time collision total when Between t_2n,

Wherein, t_nAnd t_2nAccording toCalculate and obtain；

S33. by t_n、t_2nBring formula intoObtain recovery coefficient.

Described test material also includes base, support and crossbeam；Described metallic plate and support are fixed on base, and crossbeam is pacified It is contained on support, and crossbeam is located above metallic plate, metal ball is embedded in crossbeam, in step s2, the mode of release metal ball It is to sow from crossbeam.

Described test material also includes computer, and computer is electrically connected with capture card.

After such scheme, the invention has the beneficial effects as follows: test material is simply inexpensive, and method is simple, energy Enough change over information by recording metal ball with metallic plate collision post-acceleration, can be used for determining any contact-impact material Recovery coefficient, thus obtaining the damping lagging influence in contact-impact material, so for obtain higher pair in two contact-impact materials The abrasion condition of material and its life appraisal provide essential condition.

Below in conjunction with the drawings and specific embodiments, the present invention will be further described.

Brief description

Fig. 1 is the contact-impact schematic diagram that two kinds of metal materials are constituted；

Fig. 2 is that acceleration changes over curve chart.

Specific embodiment

The test method of recovery coefficient in a kind of determination metal material contact-impact that the present invention discloses, walks including following Rapid:

S1. test prepares

Prepare test material: metal ball, metallic plate, velocity sensor and capture card, by velocity sensor with capture card even Connect；Wherein any two kinds of metal materials are obtained respectively for metal ball and metallic plate；

S2. process of the test

Release metal ball so as to from falling apart from the eminence of h with metallic plate, collide metallic plate for the first time in metal ball until During stopping at metallic plate, velocity sensor obtains the metal ball accekeration of collision rift and collision every time on a metal plate Time value, common m time, the acceleration of note i ＆ lt collection is a_i, a_iCorresponding time value t_i, 1≤i≤m；Capture card gathers this acceleration Angle value and time value；

S3 experimental data processing, comprises the following steps:

S31. the time value according to corresponding to accekeration and acceleration makes acceleration time history plot；

S32. observe the peak value corresponding time t of described curve chart_i, obtain the i-th -1 time collision and i ＆ lt collision successively Time interval is δ t_i, collide the total time t of (n+1)th collision the 1st time_n, collide the 1st time the 2n+2 time collision total when Between t_2n,

Wherein, t_nAnd t_2nAccording toCalculate and obtain；

S33. by t_n、t_2nBring formula intoObtain recovery coefficient.

Described test material also includes base, support and crossbeam；Described metallic plate and support are fixed on base, and crossbeam is pacified It is contained on support, and crossbeam is located above metallic plate, metal ball is embedded in crossbeam, in step s2, the mode of release metal ball It is to sow from crossbeam.

Described test material also includes computer, and computer is electrically connected with capture card, and computer can obtain collection in real time Block gathered data, and acceleration time history plot can quickly be provided by modes such as Cheng Tu.

It is below the experimental data processing principle of the present invention:

Table 1 below is the time dependent test data of acceleration

Metal ball the i-th -1 time and i ＆ lt collision metal corresponding time are respectively t_i-1And t_i, corresponding acceleration is respectively For a_i-1And a_iIt is assumed that metal ball the i-th -1 time and i ＆ lt collision metallic plate corresponding speed are v_i-1And v_i, then have:

$e=\frac{v_i}{v_{i-1}}=\mathrm{...}=\frac{v_2}{v_1}---\left(3\right)$

Can be obtained by formula (3):

v_i=ev_i-1=e²v_i-2=...=eⁱv₁(4)

WhereinFor corresponding speed during the 1st collision metallic plate of metal ball.

The time interval of the i-th -1 time collision of metal ball and i ＆ lt collision is δ t_i=t_i-t_i-1, the collision of bead (a) i ＆ lt Corresponding speed v during long square plate (b)_iWith time interval δ t_iRelation be:

v_i=g δ t_i/2 (5)

Can be obtained by formula (4) and formula (5):

${\mathrm{\δt}}_i=\frac{2e^i{v}_1}{g}=e^i\sqrt{\frac{8h}{g}}---\left(6\right)$

Obviously, from the total time colliding (n+1)th collision for the 1st time it isThen

$t_n=\underset{i=1}{\overset{n}{\σ}}\left(e^i\right)=\sqrt{\frac{8h}{g}}\frac{1-e^n}{1-e}---\left(7\right)$

Can be obtained by formula (7):

$t_{2n}=\underset{i=1}{\overset{2n}{\σ}}\left(e^i\right)=\sqrt{\frac{8h}{g}}\frac{1-e^{2n}}{1-e}---\left(8\right)$

Can be obtained divided by formula (8) by formula (7):

$e^{2n}-\frac{t_{2n}}{t_n}{e}^n+\frac{t_{2n}}{t_n}-1=0---\left(9\right)$

Solution formula (9) can obtain:

$e={(\frac{t_{2n}}{t_n}-1)}^{\frac{1}{n}}---\left(10\right)$

Thus obtaining the metal ball accekeration of each collision rift and collision time value on a metal plate, calculate above-mentioned general t_nAnd t_2nJust can go out recovery coefficient e.

It is below the instance data data processing procedure being recorded using the test method of the present invention:

Table 2 below is the time dependent test data of acceleration

It show acceleration with reference to 2 and change over curve.

Experimental data processing process is as follows:

(1) take 8 acceleration peak values corresponding time from Fig. 2, as shown in table 3 below:

Sequence number	1	2	3	4	5
						Time (s)	1.263	1.641	1.914	2.125	2.298
Sequence number	6	7	8	9
						Time (s)	2.446	2.568	2.67	2.762

(2) calculate 8 time corresponding time interval δ t_i, as shown in table 4 below:

Sequence number	1	2	3	4
					Time interval δ ti	0.378	0.273	0.211	0.173
Sequence number	5	6	7	8
					Time interval δ ti	0.148	0.122	0.102	0.092

(3) basisMake n be respectively 4 and 8, t can be calculated₄=1.035 and t₈=1.642；

(4) basisMake n=4, can calculate e is 0.8751.

These are only the specific embodiment of the present invention, not the restriction to protection scope of the present invention.All setting according to this case The equivalent variations that meter thinking is done, each fall within the protection domain of this case.

Claims (3)

1. a kind of test method determining recovery coefficient in metal material contact-impact is it is characterised in that comprise the following steps:

S1. test prepares

Prepare test material: metal ball, metallic plate, velocity sensor and capture card, velocity sensor is connected with capture card；

S2. process of the test

Release metal ball is so as to from falling apart from the eminence of h with metallic plate, collide metallic plate for the first time until stopping in metal ball During metallic plate, velocity sensor obtains the metal ball accekeration of each collision rift and collision time on a metal plate Value, common m time, the acceleration of note i ＆ lt collection is a_i, a_iCorresponding time value t_i, 1≤i≤m；Capture card gathers this accekeration And time value；

S3 experimental data processing, comprises the following steps:

S31. the time value according to corresponding to accekeration and acceleration makes acceleration time history plot；

S32. observe the peak value corresponding time t of described curve chart_i, obtain the i-th -1 time collision and the time of i ＆ lt collision successively It is spaced apart δ t_i, collide the total time t of (n+1)th collision the 1st time_n, collide total time of the 2n+2 time collision the 1st time t_2n,

Wherein, t_nAnd t_2nAccording toCalculate and obtain；

S33. by t_n、t_2nBring formula intoObtain recovery coefficient.

2. a kind of test method determining recovery coefficient in metal material contact-impact as claimed in claim 1, its feature exists In: described test material also includes base, support and crossbeam；Described metallic plate and support are fixed on base, and crossbeam is arranged on On support, and crossbeam be located at metallic plate above, metal ball is embedded in crossbeam, in step s2, release metal ball mode be from Sow on crossbeam.

3. a kind of test method determining recovery coefficient in metal material contact-impact as claimed in claim 1, its feature exists In: described test material also includes computer, and computer is electrically connected with capture card.