Experimental study of mechanically stressed composite materials

Experimental study of mechanically stressed composite materials

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The phenomenon of stochastic electromagnetic emission (EME) from solids is based on the generation of an electromagnetic field accompanying the mechanical excitation of the solids in question. This phenomenon is generally termed fractoemission. Our experiments were carried out on a composite dielectric material, consisting of fibrous glass reinforcement which was bound with resin-based binding agents. Our model assumes that the crack walls get charged with electric charges +q(t) and q(t) in consequence of the bonding electron statistical distribution during the crack forming process. The crack walls are moving with a velocity v(t). Both mentioned quantities can therefore be regarded as random processes. The time development of a voltage u(t) across a load resistor being connected in series with a sensing capacitor was measured. The time behaviour of the product of the electric charge and its velocity q(t).v(t) can be determined from the voltages u(t). The crack generation process may be split into two phases. The first phase includes the crack generation. In this phase, both this quantities are varying. During the second phase, the crack walls are moving while the charge they are carrying is virtually stabilized. This method is a convenient tool for study of microcracks arising in stressed solid dielectric materials.

The phenomenon of stochastic electromagnetic emission (EME) from solids is based on the generation of an electromagnetic field accompanying the mechanical excitation of the solids in question. This phenomenon is generally termed fractoemission. Our experiments were carried out on a composite dielectric material, consisting of fibrous glass reinforcement which was bound with resin-based binding agents. Our model assumes that the crack walls get charged with electric charges +q(t) and q(t) in consequence of the bonding electron statistical distribution during the crack forming process. The crack walls are moving with a velocity v(t). Both mentioned quantities can therefore be regarded as random processes. The time development of a voltage u(t) across a load resistor being connected in series with a sensing capacitor was measured. The time behaviour of the product of the electric charge and its velocity q(t).v(t) can be determined from the voltages u(t). The crack generation process may be split into two phases. The first phase includes the crack generation. In this phase, both this quantities are varying. During the second phase, the crack walls are moving while the charge they are carrying is virtually stabilized. This method is a convenient tool for study of microcracks arising in stressed solid dielectric materials.

electromagnetic emission, acoustic emission, crack, composite material

electromagnetic emission, acoustic emission, crack, composite material

KOKTAVÝ, P.; KOKTAVÝ, B.

2010

02.09.2008

Vutium

Brno

9781617823190

Multilevel Approach to Fracture of Materials, Components and Structures (ECF17)

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2517

2522

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