Apparatus and method for measuring noncontact Hopkinson pressure bar

Abstract

Embodiments of the invention provide an apparatus and method for measuring a noncontact Hopkinson pressure bar. The apparatus comprises a pressure bar system, an optical-fiber speed measurement system, a speckle interferometryspeckle pattern interference system, a point detector and a data acquisition and processing system. A tested material test sample is arranged between an incidence bar and a transmission bar of the pressure bar system, compressive stress pulses generated by striking the incidence bar by a striking bar after being stressed are transferred in the direction towards the tested material test sample, and the speed of the striking bar is measured by the optical-fiber speed measurement system; and the compressive stress pulses influence the light intensity on the incidence bar and the transmission bar to form speckle pattern intensity information by virtue of the speckle interferometrypattern interference system; and the information detected by the point detector is transmitted to the data acquisition and processing system, so that the information of the tested material such as stress, strain, strain rate and the like can be calculated. By combining an in-plane displacement measurement method and a Hopkinson pressure bar measurement method in the time-domain speckle pattern interferometry, the noncontact and high-accuracy measurement of dynamic properties for small-sized materials can be realized.

Description

technical field [0001] The invention relates to the technical field of Hopkinson pressure bar measurement, in particular to a non-contact Hopkinson pressure bar measurement device and method. Background technique [0002] The mechanical response of materials under impact loads is very different from that under static loads; nowadays, the mechanical response characteristics of materials under impact loads are widely used in military and civilian actual production , which makes it more and more important to scientifically and systematically study the dynamic mechanical properties of materials under different impact loads. In order to study the dynamic mechanical properties of materials under impact loads, SHPB (Split Hopkinson Pressure Bar, split Hopkinson pressure bar) measurement technology has been proposed. [0003] In the prior art, the strain-gauge-type separate Hopkinson pressure bar measurement device used to analyze the dynamic mechanical properties of materials is c...

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Problems solved by technology

[0004] The above-mentioned device for analyzing the dynamic mechanical properties of materials using the strain gauge-type separate Hopkinson compression rod measurement technology in the prior art has the following disadvantages: the device uses the strain gauges attached to the incident rod and the transmission rod to realize the test of the material under test. The measurement of such dynamic mechanical properties requires that the strain gauge and the incident rod and the transmission rod have good bonding characteristics. If the bond between the strain gauge and the rod is not good, it will have a great impact on the experimental results. At the same time, the measurement accuracy provided by this contact measurement method is limited.

Secondly, with the rapid development of the machinery industry and the national defense industry, higher requirements are put forward for the measurement of the dynamic mechanical properties of materials at high strain rates. In the traditional strain gauge Hopkinson bar measurement method When the diameter of the rod is less than 3 mm, the strain gauge and the pressure rod cannot be reliably pasted, which makes this Hopkinson pressure rod measurement method unable to complete small-sized materials at high strain rates (10 2 ~10 4 1 / s) accurate measurement of mechanical properties

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