CN211087666U

CN211087666U - Single-arm electric bridge metal Young modulus tester

Info

Publication number: CN211087666U
Application number: CN201821888850.XU
Authority: CN
Inventors: 王俊平; 陈庆东
Original assignee: Binzhou University
Current assignee: Binzhou University
Priority date: 2018-11-16
Filing date: 2018-11-16
Publication date: 2020-07-24
Anticipated expiration: 2028-11-16

Abstract

The utility model provides a single armed bridge surveys metal young modulus experiment appearance, includes plank, wooden support, sheep eye self tapping screw, wire, pulley guide rail, hook sign indicating number, single armed bridge, first wire, second wire, the plank left side is fixed with the wooden support, be fixed with sheep eye self tapping screw on the wooden support, sheep eye self tapping screw is connected to the wire initiating terminal, pulley guide rail connection hook sign indicating number is walked around to the wire end, the initiating segment of wire is connected to the one end of first wire, and the other end is connected to on the left side terminal of the "Rx" of single armed bridge, the end of wire is connected to the one end of second wire, and the other end is connected to on the right side terminal of the "Rx" of single armed bridge. The single-arm electric bridge metal Young modulus tester is ingenious in conception, simple to operate, high in measurement accuracy and capable of being widely applied to college physical experiment teaching.

Description

Single-arm electric bridge metal Young modulus tester

Technical Field

The invention belongs to the technical field related to experimental teaching equipment, and particularly relates to a single-arm electric bridge metal Young modulus tester.

Background

Young modulus (also called elastic modulus) is one of parameters for measuring the elastic deformation capacity of a solid material after being stressed, namely an important physical quantity for describing the elastic deformation resistance of the material, is an important basis for selecting a proper material in production and scientific research, is a common parameter in engineering technical design, and has important significance in scientific research and technical application.

In college physical experiments, the measurement of the Young's modulus of a solid material is one of experiments which must be done in physical experiments of science and technology institutions, and a plurality of experiments for measuring the Young's modulus by different methods are provided in many colleges and universities to form an experiment project sub-series with relative independence. The Young modulus measurement experiment includes a series of basic ideas and methods of physical experiments, for example, the measurement of a plurality of length quantities is related, and conventional length measurement tools such as a screw micrometer and a vernier caliper need to be selected; for the measurement of the tiny displacement, the traditional optical lever, a reading microscope, a modern Hall position sensor and the like can be selected; the standard deviation calculation and uncertainty evaluation can be carried out according to different level requirements by using an error transfer formula; the data processing uses least square method, difference-by-difference method and mapping extrapolation method. Therefore, the Young modulus measurement experiment has important value in helping students accumulate scientific research primary experience, and provides an excellent practical training platform for improving the operation skills and comprehensive qualities of the students.

Currently, the young's modulus measurement methods generally include: stretching, vibration, internal friction, beam bending, and the like. In addition, through search, the prior art also shows that the Young modulus is measured by using experimental devices and technologies such as a light displacement sensor, moire fringes, an eddy current sensor and a wave transfer technology.

For the measurement of the involved micro-elongation, a beam bending method is often used in college physical experiments, and the young's modulus of the metal material is determined according to the optical lever amplification principle. However, the device for measuring the Young modulus by the method has the following defects:

(1) the sag of the midpoint downward bending of the rectangular interface metal beam is measured by an amplification system consisting of an optical lever, a telescope and a scale, the method is ingenious in conception, and the principle is abstract and difficult to understand.

(2) The telescope is difficult to adjust, and the attention is more, utilizes the telescope to observe the measurement through the naked eye, and is easy to be wrong with the data, influences the accuracy of result.

(3) The length of the sample to be measured is usually about 1m, so the natural bending of the sample to be measured brings about a certain measurement error.

(4) The reading of the ordinary graduated scale is adopted, the error is large, the measuring result is not accurate enough, and the like.

The single-arm bridge is a comparison type instrument, and 1 resistor R to be measured is required_xIt is compared with another 3 resistors R₂、R₃、R₄To form a bridge circuit. When the bridge circuit is connected with a power supply, if the potentials of the middle points of the 2 bridges are equal, the current in the circuit connected with the two points is equal to zero. If a galvanometer is connected between the two points, the pointer of the galvanometer points to zero at the moment, and the bridge balance is called at the moment; when the bridge is balanced, the measured resistance R_x=R₄R₂/R₃。

Disclosure of Invention

In order to overcome the not enough of prior art, the utility model provides an it surveys metal Young modulus experiment appearance to be easy and simple to handle, measurement accuracy is high, the available single armed electric bridge of teaching experiment.

The development principle of the single-arm bridge metal Young modulus experimental instrument is that an electrical formula R = rho L/S is converted into a formula L = RS/rho, the resistivity rho of the metal wire is a fixed value, the cross section area S of the metal wire can be calculated by measuring the diameter with a vernier caliper, the change is very small and can be ignored, and the length △L = S of the metal wire before and after stretching (R = rho) (R is the length of the metal wire before and after stretching)_x2-R_x1)/ρ，R_x1And R_x2Young' S modulus is calculated by E = F L/S △L, where F is the weight of the hook weight attached to the lower end of the wire, L is the length of the wire, and △L = S (R)_x2-R_x1) Bringing the/p to E = F L \ S △L young' S modulus of available wire E = F L ρ/S (R = F L ρ/S)_x2-R_x1) Namely, the formula is a calculation formula of the Young modulus of the metal.

The utility model discloses a realize through following technical scheme: the utility model provides a single armed bridge surveys metal young modulus experiment appearance, includes plank, wooden support, sheep eye self tapping screw, wire, pulley guide rail, hook sign indicating number, single armed bridge, first wire, second wire, first fastener, second fastener, the plank left side is fixed with the wooden support, be fixed with sheep eye self tapping screw on the wooden support, sheep eye self tapping screw is connected to the wire initiating end, pulley guide rail connection hook sign indicating number is walked around to the wire end, the initial section of wire is connected through first fastener to the one end of first wire, the other end of first wire is connected to on the left side terminal of the "Rx" of single armed bridge, the end of wire is connected through the second fastener to the one end of second wire, the other end of second wire is connected to on the right side terminal of the "Rx" of single armed bridge.

Furthermore, the pulley guide rail and the sheep eye self-tapping screw are positioned on a horizontal straight line parallel to the wood board.

Furthermore, the wood board is fixed on a table top through screws.

Furthermore, the wood support is fixed on the left side of the wood board through screws, and the pulley guide rail is fixed on the right side of the wood board through screws.

The utility model has the advantages of: through the method of measuring the change of wire resistance, turn into the measurement of the change of wire resistance under the exogenic action to the measurement of the elongation of wire when receiving the exogenic action, utilize the single armed bridge to measure the change of wire resistance very easily, consequently the utility model discloses measure metal Young's modulus, the experimental principle is simple, and the experiment degree of difficulty is little, and it is convenient to measure, easy to operate.

Drawings

The present invention will be further described with reference to the accompanying drawings.

Fig. 1 is the structural schematic diagram of the single-arm electric bridge metal young modulus tester of the utility model.

In the figure, 1 wood board, 2 wood brackets, 3 sheep eye self-tapping screws, 4 metal wires, 5 pulley guide rails, 6 hook codes, 7 single-arm bridges, 8 first wires, 9 second wires, 10 first wire clamps and 11 second wire clamps.

Detailed Description

The attached drawing is a concrete embodiment of the utility model. The embodiment is shown in fig. 1, and the experimental instrument for measuring the young's modulus of metal by using the single-arm electric bridge comprises a wood board 1, a wood support 2, a sheep eye self-tapping screw 3, a metal wire 4, a pulley guide rail 5, a hook code 6, a single-arm electric bridge 7, a first lead 8, a second lead 9, a first clamp 10 and a second clamp 11, wherein the wood board 1 is fixed on a desktop through screws, the wood support 2 is fixed on the left side of the wood board 1 through screws, the sheep eye self-tapping screw 3 is fixed on the wood support 2, the initial end of the metal wire 4 is connected with the sheep eye self-tapping screw 3, the tail end of the metal wire passes through the pulley guide rail 5 and extends to the hook code 6 in the vertical direction, the pulley guide rail 5 is fixed on the right side of the wood board 1 through screws, one end of the first lead 8 is connected with the initial end of the metal wire 4 through the first clamp 10, the other end of the first lead 8 is, one end of the second wire 9 is connected to the end of the wire through a second clip 11, and the other end of the second wire 9 is connected to the right terminal of the "Rx" of the one-arm bridge 7, and the terminals are tightened to reduce the contact resistance.

The measuring method of the single-arm bridge metal Young modulus tester comprises the following steps of firstly measuring the length L of a metal wire by using a ruler, then measuring the diameter of the metal wire by using a vernier caliper, calculating the cross section area S, calculating the weight F of a hook code by using the mass of the hook code, firstly estimating the resistance of the metal wire by using a universal meter before using the single-arm bridge for measurement, selecting a comparison arm according to the deflection direction of the galvanometer, adjusting the balance of the bridge, and respectively measuring the resistance R of the metal wire before and after stretching_x1And R_x2Formula E = F L ρ \ S (R = F L ρ \ S)_x2-R_x1) The Young's modulus E of the wire is obtained.

Claims

1. A single-arm electric bridge test metal Young modulus experimental instrument is characterized in that: the wood board comprises a wood board (1), a wood support (2), a sheep-eye self-tapping screw (3), a metal wire (4), a pulley guide rail (5), a hook code (6), a single-arm bridge (7), a first wire (8), a second wire (9), a first wire clamp (10) and a second wire clamp (11), wherein the wood board left side is fixed with the wood support (2), the sheep-eye self-tapping screw (3) is fixed on the wood support, the starting end of the metal wire is connected with the sheep-eye self-tapping screw, the tail end of the metal wire bypasses the pulley guide rail (5) to connect the hook code (6), one end of the first wire (8) is connected with the starting section of the metal wire through the first wire clamp (10), the other end of the first wire (8) is connected to a left-side wiring terminal of Rx (7) of the single-arm bridge, one end of the second wire (9) is connected with the tail end of the metal wire, the other end of the second lead (9) is connected to a right side binding post of Rx of the single-arm bridge (7), and the pulley guide rail (5) and the sheep eye self-tapping screw (3) are positioned on a horizontal straight line parallel to the wood board.

2. The single-arm bridge-testing metal Young's modulus tester as claimed in claim 1, wherein the testing apparatus is characterized by: plank (1) passes through the screw fixation on the desktop, wood support (2) pass through the screw fixation in the left side of plank, pulley guide rail (5) pass through the screw fixation in the right side of plank.