A composite material has a laminated structure of fiber-reinforced resin layers and films of a shape-memory alloy. A predetermined strain has been applied to each film. A damage sensor has a film of an alloy of nickel and titanium. An electric circuit is bonded to the film, and strain gages are conn
A composite material has a laminated structure of fiber-reinforced resin layers and films of a shape-memory alloy. A predetermined strain has been applied to each film. A damage sensor has a film of an alloy of nickel and titanium. An electric circuit is bonded to the film, and strain gages are connected to the electric circuit. The damage sensor can be laminated to the resin layers in place of the film of the shape-memory alloy. Damage to the composite material is suppressed as follows: A current is applied to the films of the shape-memory alloy, to monitor change in electric resistance of the films. The damage is located in response to the change in electric resistance. Another current is applied to a film of the shape-memory alloy for which the change is larger than the other films to generate heat for deforming the film to generate shrinking stress or shear stress to the damage.
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What is claimed is: 1. A method of controlling damage to a composite material, comprising; applying a current to films of shape-memory alloy, a predetermined strain having been applied to each film, each film being provided between fiber-reinforced resin layers of the composite material, to monitor
What is claimed is: 1. A method of controlling damage to a composite material, comprising; applying a current to films of shape-memory alloy, a predetermined strain having been applied to each film, each film being provided between fiber-reinforced resin layers of the composite material, to monitor change in electric resistance of the films; locating damage to the composite material in response to the change in electric resistance; and applying another current to one of the films of the shape-memory alloy for which the change is larger than the other films to generate heat for deforming the film to generate pressure or shear stress to the damage. 2. The method according to claim 1, wherein the current applied in the step of applying a current is a constant small current. 3. The method according to claim 1, wherein the current applied in the step of applying another current is larger than the current applied in the step of applying a current. 4. The method according to claim 1, wherein the one of the films is the film in which the electrical resistance is changed. 5. A method of controlling damage to a composite material, comprising: applying a current to films of shape-memory alloy, a predetermined strain having been applied to each film, each film being provided between fiber-reinforced resin layers of the composite material; monitoring change in electric resistance of the films; detecting a film in which the electrical resistance is changed; locating a damaged position of the composite material from the film in which the electrical resistance is changed; and deforming one of the films so as to generate pressure or shear stress to the damage. 6. The method according to claim 2, wherein a constant small current is applied to the films. 7. The method according to claim 3, further comprising: flowing a current so as to heat the one of the films. 8. The method according to claim 4, wherein the current flown in the flowing step is larger than the constant small current applied in the applying step. 9. The method according to claim 2, wherein the one of the films deformed in the deforming step is the film detected in the detecting step. 10. A method of controlling damage to a composite material of laminations of fiber reinforced resin layers and films of a shape-memory alloy, comprising the steps of: locating a plurality of strain gauges at spaced-apart locations on the material, wherein each of said strain gauges comprises one of the fiber-reinforced resin layers and a plurality of the shape-memory alloy films that are laminated with the one resin layer positioned between two of the alloy films being located on the upper and the lower sides of the one resin layer and having different strains from each other; applying a current to the alloy films in respective ones of the strain gauges, a predetermined strain having been applied to each film, each alloy film being provided between fiber-reinforced resin layers of the composite material, to monitor change in electric resistance of the films; locating damage to the composite material in response to the changes in electric resistance of respective ones of the strain gauges; and applying another current to one of the films of the shape-memory alloy for which the change is larger than in other ones of the alloy films to generate heat for deforming the film to generate pressure or shear stress to the damage. 11. A method of controlling damage to a composite material of laminations of fiber reinforced resin layers and films of a shape-memory alloy, comprising the steps of: locating a plurality of strain gauges at spaced-apart locations on the material, wherein each of said strain gauges comprises one of the fiber-reinforced resin layers and a plurality of the shape-memory alloy films that are laminated with the one resin layer positioned between two of the alloy films being located on the upper and the lower sides of the one resin layer and having different strains from each other; applying a current to the alloy films in respective ones of the strain gauges, a predetermined strain having been applied to each film, each alloy film being provided between fiber-reinforced resin layers of the composite material; monitoring change in electric resistance of the films in respective ones of the strain gauges; detecting a film in which the electrical resistance is changed; locating a damaged position of the composite material from the film in which the electrical resistance is changed, the locating of the damaged position being accomplished by evaluation changes in voltage appearing on individual ones of the strain gauges; and deforming one of the films by application of electric current thereto so as to generate pressure or shear stress to the damage.
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이 특허에 인용된 특허 (4)
Ogisu, Toshimichi; Nomura, Masato; Ando, Norio, Composite material and method of controlling damage thereto and damage sensor.
Jacobs Jack H. ; Thomas Matthew M. ; Grosskrueger Duane D. ; Carpenter Bernie F. ; Perry Alan R., Composite structure adapted for controlled structural deformation.
Jacobs Jack H. (St. Louis MO) Thomas Matthew M. (Madison IL) Grosskrueger Duane D. (Highlands Ranch CO) Carpenter Bernie F. (Littleton CO) Perry Alan R. (Morrison CO), Fabrication method for composite structure adapted for controlled structural deformation.
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