LT4057B - Measuring arrangement for measuring curvature of surface of thin-walled anisotropic shell - Google Patents

Abstract

Invention applies to the material testing and measurement of thin structures and may be used for design and manufacture of goods (garments, foot-wear), construction structures (hangars) and flying apparatus (balloons, etc.). It essentially expands the functional possibilities of the measuring instruments used to measure the thin wall anisotropic shell surface curvature as the instrument creates conditions to measure both the positive and negative curvature surfaces. The instrument consists of a sample (6) pressure device (1), sample load device (2) and a sample bending measuring device (3). The latter is placed under the sample (6) and is made of vertical two pin branches (14), symmetrically touching the sample (6) and a micrometer (15), all being mounted on a disk (16) with a turning angle position fastener (28), and vertically moving frame (18) where there is screw installed (19). The screw has opposite direction treads on its ends and holds the branch (14) pins (24, 25) with two sliders (22, 23). The screw can also change the distance between the pins.

Description

The invention relates to the field of material testing and measurements of thin structures and can be used in the design and manufacture of household products (clothing, footwear), building structures (hangars) and flying apparatus (balloons, etc.).

Known device for measuring the curvature of thin anisotropic shells under pneumatic or hydraulic loading. The device has a specimen clamping device, a pneumatic or hydro actuator, and two inductive sensors mounted on the disc and the measuring surface of the cores touching the cores (see former USSR Certificate No. 257839, TPK G01 B, (45k, 50), 1968).

This device is quite complex in design, difficult to adjust and is only suitable for measuring the curvature of shells which are formed by an evenly distributed pressure, ie gas or liquid pressure.

Another similar device for measuring the curvature of thin anisotropic shells under pneumatic loading is also known. This device incorporates a specimen clamp, a compressed air sample, and a pneumatic transducer to measure specimen deflection (see Former USSR Auth. Certificate No. 281879, TPK G01B 13/16, 1968).

This device is also quite sophisticated and its operation is based on the determination of evenly loaded radius of curvature of the shell based on the shell deflection at the supports of the swivel pneumatic sensor frame, which are not adjusted. Therefore, the device must have a set of interchangeable frames whose replacement reduces the accuracy of measurement or renders it completely impossible if the curvature differences between the shell meridians are large enough. If the shell is formed by unevenly distributed pressures, such as a balloon or other form of puff, the differences in shape and curvature between the meridians are not only large, but they also have a different sign transitioning from a convex to a curved shell. The known device and its main element, the pneumatic sensor, is not suitable for measuring the curvature of such shell meridians. Its main disadvantage is its narrow functionality, as it can only measure thin-walled (convex) thin-walled shells. However, due to its similarity with the main features of the present invention, it is considered a prototype.

The object of the invention is to extend the functional capabilities of devices for measuring surface curvature of anisotropic shells.

This object is achieved by placing a device under the specimen in a device for measuring the surface curvature of thin-walled anisotropic shells consisting of a specimen clamping device, a specimen loading device and a specimen deflection measuring device, consisting of a vertical toe, symmetrical, mounted on a disc having a pivot angle lock and a vertically movable frame having a screw having different threads in the ends and holding the forks of the forks through two sliders.

The invention is illustrated in the drawings; Fig.1 - a schematic diagram of the device; FIG. 2 - top view of the shell; FIG. 3 is the moment of measurement of the short meridian M1 deflection; FIG. 4 is the moment of measurement of the deflection of the long meridian M2.

The device consists of a clamping device 1, a loading device 2 and a deflection measuring device 3. All three parts are mounted on a common stand 4 fixed to the plate 5. The clamping device 1 of the specimen 6 consists of two rings 7 and 8. The specimen 6 the loading device 2 consists of an indentator 9, a stem 10, a platform 11, a roof 12 and a guide 13. The deflection measuring device 3 of the specimen 6 consists of a fork 14 and a micrometer 15 mounted on a disk 16 in a socket 17 having a frame 18 screw 19 with threads of different directions (left and right) at ends 20, 21, sliders 22,. 23 and fork 14 with fingers 24, 25. Screw 19 has a graduated head 26, fork 14 a removable base stencil 27, and socket 17 a latch 28.

If the specimen 6 has a pronounced anisotropy (deformation non-uniformity in different directions), then the indenter 9 forms a shell 29 with a different shape of meridians, which in FIG. 3 and FIG. 4 marked M1 for short and M2 for long. They are 90 ° to each other (Fig. 2).

The preformed disc-shaped specimen 6 (of film, fabric, or other material) is firmly pressed between the rings 7 and 8. The indenter 9 is then placed on the specimen and loaded with a load 12 (e.g., weight) over the stem 10 and platform 11. The specimen 6 bends to form a soft shell 29 of complex shape whose measurement of curvature of the surface begins with the determination of the base position. For this purpose, a basing stencil 27 is used, which is placed on the forks 14, 24 and 25 and lifted up to contact with the specimen 6 by means of a micrometer 15 (fig. 1). here the scale of the micrometer 15 is set to zero and the stencil 27 is removed. The disk 16 is pivoted in the slot 17 so that the latch 28 engages it at the short meridian M1 of the shell 29 (or at the position 0 ^o -0 ^o ₎ in FIG. 2, FIG. 3). By lifting the fork 14 with the micrometer 15, the uppermost fingers 24, 25 easily replace the specimen 6 (Fig. 3). Subtract the deflection Δ1 on the 15 micrometer scale. The disk 16 is then rotated 90 ° (to 90 ° -90 °, Fig. 2, Fig. 4) and the micrometer 15 is again raised until the fingers 24, 25 touch the more inclined meridian M2. A new subtraction of the deflection z \ 2 on the 15 micrometer scale is made. Two dimensions Δ1 and Δ2 are thus measured at the same distance a between the fingers 24, 25 of the fork 14, and then the head 26 of the screw 19 is rotated and the distance a between the fingers 24, 25 is rotated (e.g., in magnification). Again, the same measurements of the deflection Δ1 and Δ2 shall be made with the same consistency. By obtaining several points on the same meridian, it is possible to determine (for example, draw or calculate) its shape and thus its curvature.

The present invention extends the functional capabilities of such devices in comparison with the known ones by substantially:

- the sample deflection measuring device is placed underneath the sample (all analogues were above the sample), which allows measuring the curvature of the shell in the presence of the creep of the shell material;

- the sample deflection measuring device consists of a double-forged fork which touches two symmetrical points of the body to be measured, does not slide to one side and gives an average of two points;

- the measuring device has a micrometer, one of the simplest and most accurate linear size counters;

- measuring elements mounted on a disc that can be rotated and at the same time measure any meridian of a complex surface (non-rotating body);

- the disc has a latch that allows all measurements to be made at the same meridians;

the measuring device has a vertically movable frame with a screw, which allows changing the base distance between the fingers;

- the screw has threads in different directions at the ends, which allow gentle and symmetrical shells to change the distance between the fingers;

- the fingers are connected to the auger by sliders which hold them in a strictly upright position.

Claims (1)

DEFINITION OF INVENTION Thin-wall anisotropic shells measuring surface curvature, consisting of a specimen clamp, a specimen loading device and a specimen deflection measuring device, characterized in that the specimen deflection measuring device is placed under the specimen and consists of a vertical fork, symmetrical to the specimen, on a disk having a pivot angle lock and a vertically movable frame having a screw having different directions of threading at the ends and two sliders holding the forks of the fork and changing the distance between them.