KV series
Crack gages


Bonded to a cracked or crack-expected part of structures and materials, the KV series gages measure the developing length and velocity of the crack. Different from usual strain gages, the grids of KV series gages is cut along with crack development, resulting in resistance change. (Utility model)


• Progress and developing velocity of a crack are electrically obtained.
• Applicable to both flat and curved surfaces.
• Resistance change vs crack length is virtually linear.
• Dedicated adapter enables use of conventional strain amplifiers.
• Extremely simple and convenient compared with the conventional optical method.
• 2 trigger wires each before and behind the grids (KV-5C) can be used for automation of measurement.

Major Properties

Materials Resistive element CuNi alloy foil
Materials Base Paper base and phenol-epoxy
Operating temperature in combination with major adhesives after curing (°C) CC-33A: -
CC-36: -
PC-600: -
Operating temperature in combination with major leadwire cables (°C) -
Self-temperature-compensation (°C) -
Applicable linear expansion coefficients (×10-6/℃) -
Strain limits at normal temp. (approx. %) -
Fatigue lives at normal temp. (times) -

Products table

All display

KV Crack gages


Model Dimensions (mm)
Gage(Grid) Base
Length Width Length Width
KV-5C 30 5
KV-25B 42 32

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CC-33A, CC-36, PC-600