HBM crack propagation gauges are used to determine crack propagation in a component. HBM offers three different types.

Types RDS20 and RDS40 consist of electrically isolated resistors. In this case individual circuits are interrupted as the crack propagates.

Type RDS22 consists of conductor tracks connected in parallel which will tear if the crack extends under the crack propagation gauge. This will gradually increase the electrical resistance of the strain gauge as the crack continues to extend.

This change in resistance can be measured using a resistance meter or strain gauge amplifier.

Connecting a Crack Propagation Gauge

Connecting an RDS crack propagation gage to an SG amplifier
Typical signal curve for RDS20 with links connected in parallel

There are two different types of crack propagation gauges: Type RDS22 consists of conductor tracks connected in parallel which will tear if the crack extends under the crack propagation gauge.

This will gradually increase the electrical resistance of the strain gauge as the crack continues to extend. Types RDS20 and RDS40 consist of electrically isolated conductor tracks, i.e. as the crack extends, individual circuits will be interrupted. If the circuits are contacted individually, the direction in which the gap is extending can be detected.

The easiest way to detect the signals of crack propagation gauges (RDS) is with a resistance measurement. Direct resistance measurements of this type can be taken with many amplifiers from HBM (e.g. MGCplus or Spider8 with the appropriate modules).

The resulting resistance (R) of the RDS is dependent on the number of torn links and can easily be calculated. In this case n identical resistors (Ri) are connected in parallel:

If a grid line is interrupted, this is described by

However, the measurement can be performed just as well with a measuring amplifier for SG measurements. The circuit diagram sketch shows how the RDS has to be complemented to obtain a resistance change that is inside the measuring range of an amplifier for strain gauge quarter bridges.

To minimize the effects of temperature, temperature-stable fixed resistors or SGs should be used as completion resistors. Greater sensitivity can be obtained by selecting a parallel resistor with a higher resistance value.

HBM의 표준 프로그램 상의 어떤 스트레인게이지로도 충분히 다루지 못한 특별한 요건을 가지고 계십니까? 현재 사용하고 계신 제품에 대한 등가 스트레인게이지를 찾고 계십니까? 자체 스트레인게이지를 설계해 본 적이 있으십니까? HBM으로 연락 주시면 여러분의 요건에 따라 맞춤형 스트레인게이지를 생산해 드리겠습니다. 최소 수량은 20패키지입니다.

여기에 귀하의 요청사항을 기재하세요.

 

Ordering
number

Nominal
(rated)
resistance

Dimensions [mm/inch]

Pitch t
Link center/
Link center
[mm/inch]

Number
of links

Vmax


 

Link
length

Measuring
grid
width

Carrier

 

Ω

a

b

c

d

1-RDS 20

13

20
0.727

22.5
0.886

28
1.102
25
0.984
1.15
0.045
20 1.5

1-RDS 22

44

22
0.866

5
0.917

27.8
1.094
6.8
0.268
0.1
0.004
50 0.8
1-RDS 40

28

40
1.575

8.4
0.331

47
1.85
10
0.394
0.85
0.033
10 2.5

 

 

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