| The research of dynamic mechanical properties of materials under high strain rate conditions has great practical significance for engineering design and engineering application in military and civil fields.Kolsky bar is a widely used experimental method for measuring the dynamic mechanical properties of materials in the high strain rate range.The traditional Kolsky bar mainly uses the strain gauge to achieve the purpose of measuring the dynamic mechanical properties of the specimen,but this method requires a good adhesion between the bar and the strain gauge,the measurement accuracy that the conventional Kolsky bar provides is limited also.In addition,in order to match micron-sized specimens requiring smaller sized systems,it is evident that traditional methods are not feasible at these orders of magnitude because the strain gauge and the bar cannot be reliably connected when the diameter of the bar is less than 3 millimeters.Give this reality,a new measurement system of non-contact and real-time Kolsky bar is presented.This system uses two sets of temporal speckle interferometry in-plane displacement measurement device to replace two strain gauges of conventional Kolsky bar.This method is non-contact,not only does not require any intermediate medium,but also have the advantage of highly repeatable,more reliable and accurate measurement results.Simultaneously,make the Kolsky bar apply to characterize dynamic mechanical properties of materials under higher strain rate and smaller size conditions.In this paper,we designed and manufactured a Kolsky bar with the diameter of 2 mm,set up a Kolsky bar measuring device based on temporal speckle interferometry,develop a data processing program base on wavelet transform,carry through the corresponding experiment to prove the feasibility of the measurement method.The main works are as following:(1)The temporal speckle interferometry in-plane displacement measurement technique was introduced into the Kolsky bar measurement,and corresponding theoretical analysis and experimental research were performed.(2)Designed and manufactured a Kolsky bar with a diameter of 2mm,and a corresponding data processing program base on wavelet transform is developed.(3)A Kolsky bar testing system based on temporal speckle interferometry displacement measurement was designed and built.The principle verification experiment was completed.The impact test was performed on the 3 04L sample and its impact loading condition was obtained. |
