Strain-detecting composite materials

A composite material comprising:

• a structural material;
• and
• a plurality of particles formed from a ferromagnetic shape-memory alloy and embedded in said structural material such that the ductility of the structural material is not adversel affected:
• wherein the composite material is configured such that when a crack forms in the composite material with a crack tip process zone at a tip of the crack and an adjacent region disposed adjacent to said crack tip process zone, such that when the crack tip process zone reaches one of the plurality of particles formed from the ferromagnetic shape-memory alloy, said ferromagnetic shape-memory alloy within said crack tip process zone changes crystallographic phase from austenite to martensite within said crack tip process zone and changes magnetic phase within said crack tip process zone in response to a predefined critical macroscopic average strain within said crack tip process zone, and wherein a strain in said adjacent region is below the predefined critical macroscopic average strain, and said ferromagnetic shape-memory alloy within said adjacent region does not change crystallographic phase from austenite to martensite within said adjacent region and does not change magnetic phase within said adjacent region;
• and
• wherein said ferromagnetic shape-memory alloy having a changed crystallographic phase from austenite to martensite does not revert to austenite from martensite upon removal of said predefined critical macroscopic average strain.

A composite material comprising:

• a laminate structure including:
• at least one layer formed from a structural material;
• and
• a shape-memory alloy embedded in said structural material such that the ductility of the structural material is not adversely affected
• wherein the composite material is configured such that when a crack forms in the structural material with a crack tip process zone at a tip of the crack, such that the shape memory alloy has a strained region disposed adjacent said crack tip process zone and an adjacent region disposed adjacent to said strained region, wherein when the crack tip process zone reaches the shape-memory alloy, said shape-memory alloy in said strained region changes crystallographic phase from austenite to martensite within said strained region in response to a predefined critical macroscopic average strain within said strained region, and wherein a strain in said adjacent region is below the predefined critical macroscopic average strain, and said shape-memory alloy in said adjacent region does not change crystallographic phase from austenite to martensite within said adjacent region;
• and
• wherein said shape-memory alloy having a changed crystallographic phase from austenite to martensite does not revert to austenite from martensite upon removal of said predefined critical macroscopic average strain.

A composite material comprising:

• a structural material;
• and
• a plurality of particles formed from a ferromagnetic shape-memory alloy and embedded in said structural material such that the ductility of the structural material is not adversely affected;
• wherein the composite material is configured such that when a crack forms in the structural material with a crack tip process zone at a tip of the crack, and such that the shape memory alloy has a strained region disposed adjacent said crack tip process zone and an adjacent region disposed adjacent said strained region, wherein when the crack tip process zone reaches the shape memory alloy, said shape-memory alloy within said strained region changes crystallographic phase from austenite to martensite within said strained region in response to a predefined critical macroscopic average strain within said strained region, and wherein a strain in said adjacent region is below the predefined critical macroscopic average strain, and said shape-memory alloy within said adjacent region does not change crystallographic phase from austenite to martensite within said adjacent region;
• wherein said shape-memory alloy having a changed crystallographic phase from austenite to martensite does not revert to austenite from martensite upon removal of said predefined critical macroscopic average strain;
• wherein said predefined critical macroscopic average strain occurs at a temperature of greater than or equal to about a martensite start temperature, Ms , of said shape-memory alloy and less than about an austenite start temperature, As of said shape-memory alloy;
• and
• wherein said shape-memory alloy generates an acoustic emission in response to said predefined critical macroscopic average strain that is greater in magnitude than an acoustic emission of said structural material.