CN106198748A - The beam deflection method using resonance principle surveys experimental provision and the method for Young's modulus - Google Patents

Abstract

The beam deflection method using resonance principle surveys experimental provision and the method for Young's modulus, relates to a kind of young modulus measuring device and method, the present invention solves that current beam deflection method surveys Experiment of Measuring Young's principle single abstract, the problem that telescope adjustment difficulty is big.Apparatus of the present invention are included on pedestal and arrange two columns, beams of metal two ends, square-section freely ride upon on the edge of a knife of column upper end, a bronze medal framework is overlapped on beams of metal, lower end arranges vibrator and metal framework, vibrator is connected with signal source, and differential bridge, alternating-current voltage source, amplifying device and oscillograph that measurement apparatus is made up of four mistors are constituted；The inventive method utilizes vibrator that sinusoidal signal is converted to mechanical vibration, making beams of metal spring oscillator make forced vibration, the electric bridge being made up of mistor is converted to the signal of telecommunication, regulates signal frequency, obtain the natural frequency of beams of metal spring oscillator when wave-shape amplitude maximum, calculate Young's modulus.The present invention is applicable to the measurement of Young's modulus.

Description

The beam deflection method using resonance principle surveys experimental provision and the method for Young's modulus

Technical field

The present invention relates to a kind of Experiment of College Physics device, be specifically related to a kind of beam deflection method using resonance principle and survey The experimental provision of Young's modulus and method.

Background technology

Under external force, the change of shape that solid is occurred, referred to as deformation.It can be divided into elastic deformation and plastic deformation Two classes.External force removes the complete restorable deformation of energy of rear object, referred to as elastic deformation.If the external force mistake being added on object Greatly, so that after external force is removed, object can not restore to the original state completely, and leaves residual deformation, the most referred to as plastic deformation.In this reality In testing, only study elastic deformation.To this end, the size of external force should be controlled, with ensure this external force remove after object resilient. Simplest deformation is bar-like object (or tinsel) by the elongation after external force and shortening.If an a length of L of object, sectional area is S, Along its length after force F, object elongation (or shortening) is Δ L.Ratio F/S is the active force in unit are, is referred to as stressing, Which determine the deformation of object；Ratios delta L/L is the specific elongation of object, referred to as strain, and it represents the size of object deformation.Press According to Hooke's law, the elastic limit internal stress at object is directly proportional to strain, proportionality coefficientIt is referred to as Young Modulus.

Experiment shows, Young's modulus is unrelated with the size of external force F, length L of object and sectional area S, and is solely dependent upon rod The material of (or tinsel).Young's modulus is to describe an important mechanics parameter of solid material elastic deformation ability, is selected One of foundation of mechanical component material, is parameter conventional in engineering.No matter it is elastomeric material, such as various metal materials, Or fragile material, such as glass, pottery etc., or other various new materials, such as fiberglass, carbon fibre composite etc., for Ensure the use of normal safe, will measure their Young's modulus.For a long time, the Young's modulus measuring material is generally adopted Use static stretch method, typically carry out on universal testing machine.This method load is big, and loading velocity is slow, there is relaxation mistake Journey, can increase measurement error, and be difficult to fragile material measure, and measures also inconvenient under condition of different temperatures.20th century The eighties, there are people's laser-holographic interferometry and laser speckle photography method that the Young's modulus of the carbon composite of aerospace field is entered Row is measured, and carrys out the impact on Young's modulus of the research material defect with this, achieves good effect.The nineties in 20th century, power Learn Young's modulus measuring method i.e. hang wire flexural resonance method to recommend to perform as national technical standard.This method can be Measure the Young's modulus of various material in the range of bigger high/low temperature, and certainty of measurement is higher.Static method except static stretch method, Also have static twist method, the method for Static bending etc.；Dynamic method except lateral resonance, also longitudinal resonance, torsional resonance etc..Additionally also Wave speed measurement method can be used, utilize continuous wave or impulse wave to measure Young's modulus.

Although kinetics Young's modulus measuring method i.e. hang wire flexural resonance method has many good qualities, but due to theory Formula is complicated, and principle is the most readily understood, and equipment is the most more complicated, and experiment difficulty is big, therefore in Experiment of College Physics at present frequently with Beam deflection method, measures the Young's modulus of metal material according to optical lever amplification principle.Optical lever amplification principle extensively should It is used in measurement technology, as low-angle change measured by ballistic galvanometer and light spot galvanometer.The most also have employing other one The most more advanced micro-displacement measurement method, such as current vortex sensor method, Michelson's interferometer method, method using in optic fiber displacement sensor Device method etc. measures the Young's modulus of metal material.Experiment of College Physics central sill bending method surveys metal material Young's modulus at present Experimental provision is primarily present following deficiency:

One, generally uses static stretch method to survey metal material Young's modulus, and principle is more single.

Its two, according to optical lever amplification principle, the amplification system consisted of optical lever, telescope and scale measures rectangle Sag curved under cross section metal beam midpoint, although method is ingenious, but principle is more abstract, the most readily understood, telescopical regulation Difficulty is bigger, and points for attention are the most, and directly utilizes telescope to carry out observing measurement by human eye, is very easy to tired Data are easily mistaken by labor, affect the accuracy of measurement result.

Its three, general use counterweight to apply pulling force to beams of metal, calculate pulling force with the nominal mass of counterweight inaccurate, thus Affect the accuracy of experimental result.

Summary of the invention

In order to overcome the above-mentioned deficiency of prior art, the present invention proposes a kind of beam deflection method using resonance principle and surveys Young The experimental provision of modulus and method, experimental principle of the present invention is easily understood, and described experimental provision utilizes vibrator by sinusoidal signal The sinusoidal signal of source output is converted to the mechanical vibration of same frequency, pass to by square-section beams of metal and copper framework, metal framework, The beams of metal spring oscillator that iron block is constituted, makes beams of metal spring oscillator make forced vibration, and this vibration is converted to by mistor Periodically variable bridge output voltage, observes the waveform of amplified bridge output voltage on analog oscilloscope, passes through The frequency of regulation sinusoidal signal, until the wave-shape amplitude maximum of bridge output voltage, now the frequency of sinusoidal signal is exactly Resonant frequency, the namely natural frequency of beams of metal spring oscillator, experimental phenomena is directly perceived, observe with measure more convenient.

The experimental provision of the beam deflection method survey Young's modulus using resonance principle that the present invention solves its technical problem is: Arranging two columns on pedestal, each two column upper ends fix a steel edge of a knife, the blade of two edges of a knife is parallel to each other, a square Tee section beams of metal two ends freely ride upon on the edge of a knife of two column upper ends, overlap a copper frame on the beams of metal of square-section Frame, copper framework and beams of metal contact position, square-section are also edges of a knife, and the copper framework edge of a knife is located exactly on two columns The edge of a knife middle of end, arranges vibrator in copper framework lower end, and vibrator is connected with a metal framework by attachment means, metal Lower portion fixes an iron block.Vibrator is connected with sine signal source by interface, the sinusoidal signal electricity of sine signal source output Pressure amplitude degree and frequency size can be continuously adjusted by knob, and can show on a display screen.Vibrator is by sine The sinusoidal signal of signal source output is converted to the mechanical vibration of same frequency, passes to by square-section beams of metal and copper framework, metal The beams of metal spring oscillator that framework, iron block are constituted, makes beams of metal spring oscillator make forced vibration.The two identical magnetic of block specifications Ferrum is separately positioned on metal framework two sides, can move up and down with metal framework, and four identical mistors of specification divide Not being arranged on four fixtures, fixture is arranged on column, and fixture can move to change position along column.By four mistors Respectively as four brachium pontis of electric bridge, constitute a differential bridge, adjustable alternating-current voltage source provide power supply, adjustable friendship to electric bridge Sinusoidal signal voltage amplitude and the frequency size of stream voltage source output can be adjusted by knob, and can be at adjustable alternating current Show on potential source display screen.The outfan concatenation operation amplifier one of electric bridge, as a backward voltage amplifier, voltage Amplification can be adjusted, by the output voltage of electric bridge by the size changing adjustable feedback resistance and adjustable input resistance Amplifying, then export through the operational amplifier two as output buffer, operational amplifier two is by interface and analog oscilloscope phase Even, the waveform of the bridge output voltage after amplifying can be shown by analog oscilloscope, observes and measures.

The beam deflection method of employing resonance principle of the present invention is surveyed the experimental provision of Young's modulus and is surveyed metal material Young The experimental technique of modulus, the detailed process of the method comprises the following steps:

Step one, by observing pedestal level gauge, adjust the pedestal leveling serew on pedestal, make square-section beams of metal water Flat；

Step 2, along column movable clamp, make Magnet one be positioned in the middle of mistor one and mistor two, make Magnet two It is positioned in the middle of mistor three and mistor four, by adjustable alternating-current voltage source function switching key, at adjustable alternating voltage Sinusoidal signal voltage amplitude and frequency size that adjustable alternating-current voltage source exports is shown respectively, by adjustable exchange on the display screen of source Voltage source voltage-regulation knob and adjustable alternating voltage source frequency adjusting knob are adjusted, and are exported by adjustable alternating-current voltage source Sinusoidal signal voltage amplitude and frequency regulation are suitable；By changing the size of adjustable feedback resistance and adjustable input resistance by computing The voltage amplification factor regulation of amplifier one is suitable, and the waveform of the bridge output voltage after being amplified by analog oscilloscope is shown Out, observed the waveform of the bridge output voltage after amplifying by analog oscilloscope display screen, further along column movable clamp, Carefully adjust mistor one, mistor two, mistor three and the position of mistor four, make the bridge output voltage be Zero, now Magnet one is positioned at the middle of mistor one and mistor two, and Magnet two is positioned at mistor three and magnetosensitive electricity The middle of resistance four；

Step 3, by sinusoidal signal voltage amplitude adjusting knob and sinusoidal signal voltage amplitude display screen, sine is believed The sinusoidal signal voltage amplitude regulation of number source output is suitable, is gradually increased sinusoidal letter by regulation sinusoidal signal frequency coarse adjustment knob The frequency of the sinusoidal signal of number source output, the machinery that the sinusoidal signal that sine signal source exports is converted to same frequency is shaken by vibrator Dynamic, pass to the beams of metal spring oscillator being made up of square-section beams of metal and copper framework, metal framework, iron block, make beams of metal bullet Spring oscillator makees forced vibration, when the frequency of sinusoidal signal is away from the natural frequency of beams of metal spring oscillator, and copper framework, metal frame Frame, iron block are the most motionless or vibration is the faintest；When the frequency of sinusoidal signal moves closer to the intrinsic frequency of beams of metal spring oscillator During rate, based on resonance principle, copper framework, metal framework, the Oscillation Amplitude of iron block are gradually increased, under metal framework drives, and magnetic Ferrum one and Magnet two do simple harmonic oscillation, therefore mistor one, mistor two, mistor three and mistor the most up and down The cyclically-varying the most therewith of magnetic induction suffered by four, the cyclically-varying therewith of the resistance of four mistors, so that Bridge output voltage the most periodically changes；

Step 4, this periodically variable bridge output voltage are after operational amplifier one amplifies, then through slow as output Rushing operational amplifier two output of device, waveform shows on analog oscilloscope, observes and put on analog oscilloscope display screen The waveform of the bridge output voltage after great, by regulation sinusoidal signal frequency fine tuning knob, the most carefully regulates sinusoidal signal The frequency size of the sinusoidal signal of source output, until the wave-shape amplitude maximum of bridge output voltage, now from sinusoidal signal The frequency read on frequency display screen is exactly resonant frequency, namely natural frequency f of beams of metal spring oscillator；

Step 5, treat beams of metal spring oscillator stop vibration, measure total matter of copper framework, metal framework, iron block and Magnet Amount m, i.e. quality m of beams of metal spring oscillator beams of metal midpoint hanging object；

Step 6, measure the effective length of square-section beams of metal with meter ruler, namely lay on two columns of this beam Distance l in the middle of two edges of a knife of end, measures the width b and height d of beams of metal square-section, square-section with slide gauge；

Step 7, by length l of square-section beams of metal, width b, highly d, quality m of beams of metal midpoint hanging object, And natural frequency f of beams of metal spring oscillator substitutes into formulaThe Young mould of beams of metal material can be obtained Amount Y.

The theoretical basis of the beam deflection method survey Young's modulus of employing resonance principle:

If the square-section beams of metal that an a length of l, width are b, height is d, when its two ends freely ride upon a pair On the parallel horizontal edge of a knife, when midpoint is by downward pulling force F effect, beam will be bent downwardly, if sag curved under beam midpoint is H, if the Young's modulus of beams of metal material is Y, if disregarding the weight of beam, and bending in elastic limit, as h ＜ ＜ l, having

$h=\frac{l^{3}F}{4d^{3}bY}---\left(1\right)$

(1) formula is become

$F=\frac{4d^{3}bY}{l^3}\·h---\left(2\right)$

According to (2) formula as, this square-section beams of metal can be regarded a coefficient of elasticitySpring.At this Square-section beams of metal midpoint hangs the object that a mass is m, then beams of metal spring and this object constitute a beams of metal spring Oscillator, applies certain pulling force to this system, then discharges, then in the vertical direction is done simple harmonic oscillation by object, and its cycle can be by The Period Formula of spring oscillator is obtained, i.e.

$T=2\mathrm{\π}\sqrt{\frac{m}{k}}---\left(3\right)$

The natural frequency of beams of metal spring oscillator is can be obtained fom the above equation

$f=\frac{1}{T}=\frac{1}{2\mathrm{\π}}\sqrt{\frac{k}{m}}---\left(4\right)$

Coefficient of elasticity by beams of metal spring(4) formula of substitution, can obtain

$f=\frac{1}{\mathrm{\π}}\sqrt{\frac{d^{3}bY}{l^{3}m}}---\left(5\right)$

According to (5) formula, Young's modulus Y wiry can be obtained, i.e.

$Y=\frac{{\mathrm{\π}}^2{l}^{3}m}{d^{3}b}\·f^2---\left(6\right)$

Applied vibration source is acted on beams of metal spring oscillator, makes beams of metal spring oscillator make forced vibration.Shake when additional When the frequency in dynamic source is not equal to the natural frequency of beams of metal spring oscillator, beams of metal spring oscillator vibrates or Oscillation Amplitude hardly The least；When the frequency in applied vibration source is equal to the natural frequency of beams of metal spring oscillator, based on resonance principle, beams of metal spring The Oscillation Amplitude of oscillator will increase suddenly.Measure frequency f in now applied vibration source, the i.e. natural frequency of beams of metal spring oscillator f.Measure length l of square-section beams of metal, width b, highly d, the matter of beams of metal spring oscillator beams of metal midpoint hanging object Amount m, it is possible to according to formula (6), obtain Young's modulus Y of beams of metal material.

The invention has the beneficial effects as follows:

One, the present invention proposes a kind of method that new beam deflection method using resonance principle surveys Young's modulus, the method The method surveying metal material Young's modulus from the beam deflection method generally used in Physical Experiments also exists essential different, and And the experimental principle of the method institute foundation is the simplest, it is simply that common mass-spring model and resonance principle, in high school physics class Just have been directed to correlation formula, course of University Physics also has detailed analysis, is easily understood.If therefore this invention is introduced In Physical Experiments, it is remarkably contributing to abundant Experiment of College Physics content, the thinking of open student, the wound of training student New spirit, strengthens student and uses knowledge problem-solving ability flexibly.

Its two, the present invention propose use resonance principle beam deflection method survey Young's modulus experimental provision the most uncomplicated, Improve a little on the basis of existing experimental provision, be easier to realize.

Its three, the experimental provision that the present invention proposes utilizes vibrator the sinusoidal signal that sine signal source export to be converted to together The mechanical vibration of frequency, pass to the beams of metal spring vibration being made up of square-section beams of metal and copper framework, metal framework, iron block Son, makes beams of metal spring oscillator make forced vibration, and this vibration is converted to periodically variable electric bridge output electricity by mistor Pressure, observes the waveform of amplified bridge output voltage on analog oscilloscope, by regulating the frequency of sinusoidal signal, until Till the wave-shape amplitude maximum of bridge output voltage, now the frequency of sinusoidal signal is exactly resonant frequency, namely beams of metal bullet The natural frequency of spring oscillator, experimental phenomena is directly perceived, observe with measure more convenient.

Accompanying drawing explanation

The present invention is further described with embodiment below in conjunction with the accompanying drawings.

Fig. 1 is the structural representation one of the present invention.

Fig. 2 is the structural representation two of the present invention.

1. pedestal in figure, 2. pedestal level gauge, 3. pedestal leveling serew, 4. column, 5. the column edge of a knife, 6. square-section gold Belong to beam, 7. copper framework, 8. the copper framework edge of a knife, 9. vibrator, 10. metal framework, 11. sine signal sources, 12. sinusoidal signal frequencies Display screen, 13. sinusoidal signal frequency coarse adjustment knobs, 14. sinusoidal signal frequency fine tuning knobs, 15. sinusoidal signal voltage amplitudes show Display screen, 16. sinusoidal signal voltage amplitude adjusting knobs, the interface between 17. vibrators and sine signal source, 18. iron blocks, 19. Mistor one, 20. mistors two, 21. mistors three, 22. mistors four, 23. Magnet one, 24. Magnet two, 25. Adjustable alternating-current voltage source, 26. adjustable alternating-current voltage source display screens, 27. adjustable alternating-current voltage source voltage-regulation knobs, 28. is adjustable Alternating voltage source frequency adjusting knob, 29. adjustable alternating-current voltage source function switching keys, 30. adjustable feedback resistance, 31. computings Amplifier one, 32. adjustable input resistances, 33. operational amplifiers two, 34. analog oscilloscopes, 35. analog oscilloscope display screens, 36. analog oscilloscope switch keys.

Detailed description of the invention

In figure, pedestal 1 arranges two columns 4, each two column 4 upper ends fix the steel edge of a knife, i.e. a column The edge of a knife 5, the blade of two edges of a knife is parallel to each other, and square-section beams of metal 6 two ends freely ride upon the cutter of two column 4 upper ends On mouth, overlapping a copper framework 7 on square-section beams of metal 6, copper framework 7 and square-section beams of metal 6 contact position are also one The edge of a knife, i.e. the copper framework edge of a knife 8, and the copper framework edge of a knife 8 is located exactly at the edge of a knife middle of two column upper ends, at copper framework 7 Lower end arranges vibrator 9, and vibrator 9 is connected with a metal framework 10 by attachment means, and metal framework 10 is internal fixing One iron block 18.Vibrator 9 is connected with sine signal source 11 by the interface 17 between vibrator with sine signal source, sinusoidal signal The sinusoidal signal voltage amplitude of source 11 output can be continuously adjusted by sinusoidal signal voltage amplitude adjusting knob 16, and can Sinusoidal signal voltage amplitude display screen 15 shows；Sinusoidal signal frequency size can pass through sinusoidal signal frequency coarse adjustment Knob 13 and sinusoidal signal frequency fine tuning knob 14 continuously adjust, and can demonstrate on sinusoidal signal frequency display screen 12 Come.The sinusoidal signal that sine signal source 11 exports is converted to the mechanical vibration of same frequency by vibrator 9, passes to by square-section gold Belong to the beams of metal spring oscillator that beam 6 is constituted with copper framework 7, metal framework 10, iron block 18, make beams of metal spring oscillator do forced oscillation Dynamic.The two i.e. Magnet 1 of the identical Magnet of block specifications and Magnet 2 24 are separately positioned on metal framework 10 two sides, can be with Metal framework 10 moves up and down, four the i.e. mistors 1 of the identical mistor of specification, mistor 2 20, magnetosensitives Resistance 3 21 and mistor 4 22 are separately positioned on four fixtures, and fixture is arranged on column 4, and fixture can move along column 4 Dynamic to change position.By four mistors i.e. mistor 1, mistor 2 20, mistor 3 21 and mistor 4 22, respectively as four brachium pontis of electric bridge, constitute a differential bridge, adjustable alternating-current voltage source 25 provide power supply to electric bridge, The sinusoidal signal voltage amplitude of adjustable alternating-current voltage source 25 output and frequency size can be respectively by adjustable alternating-current voltage source electricity Pressure adjusting knob 27 and adjustable alternating voltage source frequency adjusting knob are adjusted 28 and are adjusted, and can be at adjustable alternating voltage Show on source display screen 26.The outfan concatenation operation amplifier 1 of electric bridge, operational amplifier 1 is anti-as one To voltage amplifier, voltage amplification factor can be carried out by the size changing adjustable feedback resistance 30 and adjustable input resistance 32 Regulation, amplifies the output voltage of electric bridge, then exports through the operational amplifier 2 33 as output buffer, operational amplifier two 33 are connected with analog oscilloscope 34 by interface, and the waveform of the bridge output voltage after amplifying can be shown by analog oscilloscope 34 Out, observe and measure.

Specific experiment operating procedure is:

(1) by observing pedestal level gauge 2, adjust the pedestal leveling serew 3 on pedestal 1, make square-section beams of metal 6 water Flat.

(2) along column 4 movable clamp, make Magnet 1 be positioned at mistor 1 middle with mistor 2 20, make magnetic Ferrum 2 24 is positioned in the middle of mistor 3 21 and mistor 4 22, by adjustable alternating-current voltage source function switching key 29, Sinusoidal signal voltage amplitude and frequency that adjustable alternating-current voltage source 25 exports is shown respectively on adjustable alternating-current voltage source display screen 26 Size, is adjusted by adjustable alternating-current voltage source voltage-regulation knob 27 and adjustable alternating voltage source frequency adjusting knob 28, The sinusoidal signal voltage amplitude exported by adjustable alternating-current voltage source 25 and frequency regulation are suitable.By changing adjustable feedback resistance 30 And the size of adjustable input resistance 32 voltage amplification factor of operational amplifier 1 is regulated suitable, by analog oscilloscope 34 The waveform of the bridge output voltage after amplifying shows.The electric bridge observed after amplifying by analog oscilloscope display screen 35 is defeated Go out the waveform of voltage, further along column 4 movable clamp, carefully adjust mistor 1, mistor 2 20, mistor 3 21 and the position of mistor 4 22, making bridge output voltage is zero, and now Magnet 1 is positioned at mistor 1 and magnetic The middle of quick resistance 2 20, Magnet 2 24 is positioned at mistor 3 21 and the middle of mistor 4 22.

(3) by sinusoidal signal voltage amplitude adjusting knob 16 and sinusoidal signal voltage amplitude display screen 15, sine is believed The sinusoidal signal voltage amplitude regulation of number source 11 output is suitable.Just it is gradually increased by regulation sinusoidal signal frequency coarse adjustment knob 13 The frequency of the sinusoidal signal of string signal source 11 output, the sinusoidal signal that sine signal source 11 exports is converted to frequency by vibrator 9 The mechanical vibration of rate, pass to the beams of metal spring being made up of square-section beams of metal 6 with copper framework 7, metal framework 10, iron block 18 Oscillator, makes beams of metal spring oscillator make forced vibration.When the frequency of sinusoidal signal is away from the natural frequency of beams of metal spring oscillator Time, copper framework 7, metal framework 10, iron block 18 are the most motionless or vibration is the faintest；When the frequency of sinusoidal signal moves closer to gold When belonging to the natural frequency of beam spring oscillator, based on resonance principle, copper framework 7, metal framework 10, iron block 18 Oscillation Amplitude gradually Increasing, under metal framework 10 drives, Magnet 1 and Magnet 2 24 are simple harmonic oscillation, therefore mistor one the most up and down 19, mistor 2 20, mistor 3 21 and the magnetic induction cyclically-varying the most therewith suffered by mistor 4 22, The cyclically-varying therewith of the resistance of four mistors, so that bridge output voltage the most periodically changes.

(4) this periodically variable bridge output voltage is after operational amplifier 1 amplifies, then through as output buffering Operational amplifier 2 33 output of device, waveform shows on analog oscilloscope 34, sees on analog oscilloscope display screen 35 Examining the waveform of the bridge output voltage after amplification, by regulation sinusoidal signal frequency fine tuning knob 14, the most carefully regulation is just The frequency size of sinusoidal signal of string signal source 11 output, until the wave-shape amplitude maximum of bridge output voltage, now from The frequency read on sinusoidal signal frequency display screen 12 is exactly resonant frequency, namely natural frequency f of beams of metal spring oscillator.

(5) treat that beams of metal spring oscillator stops vibration, measure total matter of copper framework 7, metal framework 10, iron block 18 and Magnet Amount m, i.e. quality m of beams of metal spring oscillator beams of metal midpoint hanging object.

(6) measure the effective length of square-section beams of metal 6 with meter ruler, namely lay two column 4 upper ends of this beam Two distances l in the middle of the edges of a knife, measure the width b and height d of square-section beams of metal 6 square-section with slide gauge.

(7) by length l of square-section beams of metal 6, width b, highly d, quality m of beams of metal midpoint hanging object, with And natural frequency f of beams of metal spring oscillator substitutes into formulaThe Young's modulus of beams of metal material can be obtained Y。

Above the present invention is set forth, but the most conditional intention of embodiment that the present invention is introduced, not Deviating from the range of present subject matter, the present invention can have multiple changing and modifications.

Claims (2)

1. the beam deflection method using resonance principle surveys the experimental provision of Young's modulus, it is characterised in that it is included on pedestal and sets Putting two columns, each two column upper ends fix a steel edge of a knife, the blade of two edges of a knife is parallel to each other, a square-section gold Belong to beam two ends and freely ride upon on the edge of a knife of two column upper ends, square-section beams of metal overlaps a copper framework, copper frame Frame and beams of metal contact position, square-section are also edges of a knife, and the copper framework edge of a knife is located exactly at the edge of a knife of two column upper ends Middle, arranges vibrator in copper framework lower end, and vibrator is connected with a metal framework, inside metal framework by attachment means Fix an iron block；Vibrator is connected with sine signal source by interface, sinusoidal signal voltage amplitude that sine signal source exports and Frequency size can be continuously adjusted by knob, and can show on a display screen, and vibrator is defeated by sine signal source The sinusoidal signal gone out is converted to the mechanical vibration of same frequency, passes to by square-section beams of metal and copper framework, metal framework, iron block The beams of metal spring oscillator constituted, makes beams of metal spring oscillator make forced vibration；

The two identical Magnet of block specifications are separately positioned on metal framework two sides, can move up and down with metal framework, four The identical mistor of specification is separately positioned on four fixtures, and fixture is arranged on column, and fixture can move along column To change position；By four mistors respectively as four brachium pontis of electric bridge, constitute a differential bridge, by adjustable alternating current Potential source provides power supply to electric bridge, and sinusoidal signal voltage amplitude and the frequency size of the output of adjustable alternating-current voltage source can pass through knob It is adjusted, and can show on adjustable alternating-current voltage source display screen；The outfan concatenation operation amplifier one of electric bridge, makees Being a backward voltage amplifier, voltage amplification factor can be by changing adjustable feedback resistance and the size of adjustable input resistance It is adjusted, the output voltage of electric bridge is amplified, then exports through the operational amplifier two as output buffer, operational amplifier Two are connected with analog oscilloscope by interface, and the waveform of the bridge output voltage after amplifying can be demonstrated by analog oscilloscope Come, observe and measure.

The beam deflection method of employing resonance principle the most according to claim 1 is surveyed the experimental provision of Young's modulus and is surveyed metal Young The experimental technique of modulus, it is characterised in that the detailed process of the method comprises the following steps:

Step one, by observing pedestal level gauge, adjust the pedestal leveling serew on pedestal, make square-section beams of metal level；

Step 2, along column movable clamp, make Magnet one be positioned in the middle of mistor one and mistor two, make Magnet two be positioned at In the middle of mistor three and mistor four, by adjustable alternating-current voltage source function switching key, show at adjustable alternating-current voltage source Sinusoidal signal voltage amplitude and frequency size that adjustable alternating-current voltage source exports is shown respectively, by adjustable alternating voltage in display screen Source voltage-regulation knob and adjustable alternating voltage source frequency adjusting knob are adjusted, the sine exported by adjustable alternating-current voltage source Signal voltage amplitude and frequency regulation are suitable；By changing the size of adjustable feedback resistance and adjustable input resistance by operation amplifier The voltage amplification factor regulation of device one is suitable, and the waveform of the bridge output voltage after being amplified by analog oscilloscope is demonstrated Come, observed the waveform of the bridge output voltage after amplifying by analog oscilloscope display screen, further along column movable clamp, young Fine control mistor one, mistor two, mistor three and the position of mistor four, making bridge output voltage is zero, Now Magnet one is positioned at the middle of mistor one and mistor two, and Magnet two is positioned at mistor three and mistor four Middle；

Step 3, by sinusoidal signal voltage amplitude adjusting knob and sinusoidal signal voltage amplitude display screen, by sine signal source The sinusoidal signal voltage amplitude regulation of output is suitable, is gradually increased sine signal source by regulation sinusoidal signal frequency coarse adjustment knob The frequency of the sinusoidal signal of output, the sinusoidal signal that sine signal source exports is converted to the mechanical vibration of same frequency by vibrator, Pass to the beams of metal spring oscillator being made up of square-section beams of metal and copper framework, metal framework, iron block, make beams of metal spring vibration Son makees forced vibration, when the frequency of sinusoidal signal is away from the natural frequency of beams of metal spring oscillator, copper framework, metal framework, Iron block is the most motionless or vibration is the faintest；When the frequency of sinusoidal signal moves closer to the natural frequency of beams of metal spring oscillator Time, based on resonance principle, copper framework, metal framework, the Oscillation Amplitude of iron block are gradually increased, under metal framework drives, and Magnet One and Magnet two do simple harmonic oscillation, therefore mistor one, mistor two, mistor three and mistor four the most up and down Suffered magnetic induction cyclically-varying the most therewith, the cyclically-varying therewith of the resistance of four mistors, so that electric Bridge output voltage the most periodically changes；

Step 4, this periodically variable bridge output voltage are after operational amplifier one amplifies, then through as output buffer Operational amplifier two export, waveform shows on analog oscilloscope, on analog oscilloscope display screen observe amplify after The waveform of bridge output voltage, by regulation sinusoidal signal frequency fine tuning knob, the most carefully regulation sine signal source is defeated The frequency size of the sinusoidal signal gone out, until the wave-shape amplitude maximum of bridge output voltage, now from sinusoidal signal frequency The frequency read on display screen is exactly resonant frequency, namely natural frequency f of beams of metal spring oscillator；

Step 5, treat beams of metal spring oscillator stop vibration, measure gross mass m of copper framework, metal framework, iron block and Magnet, I.e. quality m of beams of metal spring oscillator beams of metal midpoint hanging object；

Step 6, measure the effective length of square-section beams of metal with meter ruler, namely lay two column upper ends of this beam Distance l in the middle of two edges of a knife, measures the width b and height d of beams of metal square-section, square-section with slide gauge；

Step 7, by length l of square-section beams of metal, width b, highly d, quality m of beams of metal midpoint hanging object, and Natural frequency f of beams of metal spring oscillator substitutes into formulaYoung's modulus Y of beams of metal material can be obtained.