JPH02227630A - Extensometer mounting structure - Google Patents

Abstract

PURPOSE:To take a measurement with high accuracy by suspending an extensometer from an upper gripper by a 1st spring and providing a 2nd spring which has a spring constant equal to that of the 1st spring between a lower gripper and the extensometer. CONSTITUTION:A test-piece TP is clamped between the upper gripper 13 fitted to a fixed wall 11 through a load cell 12 and the lower gripper 14 coupled with a load mechanism. Bolts 23 and 24 are adjusted to align the center of the extensometer with the center of a gauge mark and when the overall elongation of the test-piece TP which is being loaded is uniformed, the center of the gauge mark moves down by 50% of the overall elongation. Here, the springs 27 and 28 are equal in spring constant, so the system of the springs 27 and 28 and the extensometer 50 has the same behavior of elongation with the test- piece TP. The center of the extensometer 50 moves down by about 50% of the elongation quantity of the test-piece TP. Consequently, upper and lower levers 51 are opened spreading downward symmetrically about the center line of the extensometer 50 and the tip of the levers 51 do not deviate from the gauge mark, so that elongation is measured with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a mounting structure for an extensometer for detecting elongation of a test piece.

B. Prior art FIG. 3 shows a conventional extensometer mounting structure. The extensometer 50 is suspended from a fixed wall by a suspension spring 55. and,
A pair of quartz levers 51 are connected to a test piece TP by a coil spring 52.
A quartz lever 5 that follows the displacement of the test piece TP
1 displacement is detected by a differential transformer 53 provided at the rear end, and elongation of the test piece TP is detected. Both levers 51 are connected to each other by a leaf spring 54 and biased so that both levers 5 are always parallel to each other.

C1 Problems to be Solved by the Invention Figure 4 schematically shows the mounting structure of the extensometer, with (a) showing the state under no load and (b) showing the state under load. Test piece TP depending on the load
When the lever 51 is extended, the pair of levers 51 follow it. At this time, since the extensometer 50 is suspended by the springs 55, it cannot be displaced downward by the amount that the lower lever 51L follows the elongation of the test piece TP, and as shown in FIG. Incline as in b). Therefore, there are few problems during minute displacements, but when there are large displacements, the center between the gauge points and the center of the extensometer may shift, causing the levers 51L and 51U to come off the gauge points.

The technical problem of the present invention is to displace the center position of the extensometer in substantially synchronized with the elongation of the test piece.

08 Means for Solving the Problems The extensometer mounting structure according to the present invention suspends the extensometer from the upper grip with a first spring, and also includes a first spring between the lower grip and the extensometer. The above-mentioned technical problem is solved by tensioning a second spring having a spring constant that is the same or approximately the same as the spring constant.

When the E0 action test piece stretches, the extensometer is displaced in conjunction with the second spring. Therefore, the displacement of the center between the gauge points matches the displacement of the center of the extensometer, and even if the amount of elongation becomes large, the tip of the lever will not come off from the gauge part of the test piece.

F. Embodiment FIG. 1 shows the overall configuration of an embodiment. The same parts as in FIG. 3 are given the same reference numerals, and the explanation will focus on the differences.

A grip 13 is attached to the fixed wall 11 via a load cell 12. Reference numeral 14 denotes a lower gripping tool connected to a loading mechanism (not shown), and the test piece TP is gripped between the gripping tools 13 and 14. Pars 21.22 extend horizontally from the upper grip 13 and the lower grip 14, respectively, and bolts 23.24 are screwed into the tips of the holes 25.22.
26 and locked respectively. A suspension spring 27 is installed between the upper bolt 23 and the extensometer 50, and a suspension spring 27 is installed between the upper bolt 23 and the extensometer 50.
A connecting spring 28 is disposed between the extensometer 50 and the extensometer 50, respectively. On the other hand, the tip of the lever 51.

By pulling the holding fitting 31 with a spring 32, it is positioned at the gauge point of the test piece TP.

The operation of such an extensometer mounting structure will be explained with reference to FIG. (a) is when there is no load, and (b) is when there is a load.

Adjust the position of bolts 23 and 24 to align the center SM of the extensometer 50 with the center Ω of the gauge. This state is shown in figure (a). When the test piece TP is loaded and the elongation over the entire length of the test piece TP is made uniform as shown in the graph (b), the center QM of the gauge point moves downward by 50% of the total elongation. At this time, the connection point S1 between the lever 22 and the spring 28 also moves downward by 100% of the elongation of the test piece TP, and the spring 28
8 urges the extensometer 50 downward. now.

Since the spring constants of springs 27 and 28 are equal, spring 28.2
7. The elongation of the extensometer 50 system exhibits the same behavior as the elongation of the test piece TP, as shown in the graph (b). Therefore, the center SM of the extensometer 50 is approximately 50% of the elongation of the test piece TP.
Move down by %. That is, both the center 11M of the gauge point and the center SN of the extensometer 50 move downward by the same distance.

As a result, the upper and lower levers 51U and 51L are as shown in Fig. 2(b).
As shown in FIG. 5, the extensometer 50 opens symmetrically to the center line of the extensometer 50 in a V-shape, so that there is no fear that the tip of the lever 51 will come off the reference point, and highly accurate elongation measurement is possible.

Although the lower grip is connected to the load mechanism, the present invention can also be applied to a configuration in which the upper grip or the upper and lower grips are connected to the load mechanism.

It can also be applied to magnetic or optical extensometers instead of differential transformer types. Further, although the explanation has been made regarding a high temperature extensometer, the present invention can also be applied to a general extensometer.

G0 Effects of the Invention Since the present invention is configured as described above, there is no fear that the tip of the lever will come off the test piece even if the elongation is relatively large, and highly accurate measurement is possible.

[Brief explanation of the drawing]

FIG. 1(a) is a front view of an embodiment of the extensometer mounting structure;
FIG. 1(b) is a partial top view of the same, and FIG. 2 is a diagram for explaining its operation, with FIG. 1(a) showing the state under no load and FIG. 2(b) showing the state under load. FIG. 3 is a front view showing the mounting structure of a conventional extensometer. FIG. 4 is a diagram for explaining the operation, in which (a) shows the state when there is no load and (b) shows the state when there is a load. 13: Upper grip 14: Lower grip 21, j! : Bar 27.18: Spring 31: Holding bracket 32: Spring 50: Extensometer 51 Nilever 53: Differential transformer

Claims (1)

[Claims] A pair of levers that are arranged parallel to each other and whose tips contact the test specimen and follow the relative displacement thereof, a leaf spring that is interposed between both levers and urges both levers to become parallel, and both levers. In this extensometer mounting structure, the extensometer is suspended from an upper grip by a first spring, and a first spring is provided between the lower grip and the extensometer.
A mounting structure for an extensometer, characterized in that a second spring having the same or substantially the same spring constant as the spring is provided.