Apparatus and method for non-destructive testing of structures

A system for non-destructive testing of the load bearing characteristics of a structure, said system comprising:

• an apparatus having a member (21) supported away from the surface (11 ) of the structure (10) to be tested by one or more supports (22, 24) in contact with the structure;
• measuring means (30) adapted to measure a quantity which varies with distance between the surface of the structure and a point on the said member remote from any of the said supports, said measuring means including
• an interferometer (32);
• reflecting means (34) which move responsively with deformations of the said surface;
• said reflecting means and said interferometer together define at least one external optical path which varies with said quantity;
• a probe (36) urged against the area of the structure to be tested, said probe supported so as to allow said probe to move responsively with deformations of the said area, wherein said reflecting means is attached to said probe, the probe being supported by said member by means of a low friction arrangement of circumferentially spaced races of circulating ball bearings (38a, 38b) within a housing (31) attached to said member and,
• means (40) for both applying a force on the structure and varying repetitively said force in a predetermined manner, at a location near the area to be tested.

A system for non-destructive testing of the load bearing characteristics of a structure, said system comprising:

• an apparatus having a member (21) supported away from the surface (11 ) of the structure (10) to be tested by one or more supports (22, 24) in contact with the structure and measuring means (30) adapted to measure a quantity which varies with distance between the surface of the structure and a point on the said member remote from any of the said supports;
• and,
• means (40) for both applying a force on the structure and varying repetitively said force in a predetermined manner, at a location near the area to be tested, wherein the means for applying a force includes means (58) for oscillating a mass and means (45) for transmitting the force to the surface of the structure and said means for oscillating a mass including:
• a mass (62) slidably mounted on at least one column (64, 65) and having a centre of gravity;
• a motor (48) for rotating a shaft;
• means (50, 52, 54, 56, 58) for converting the rotary motion of said shaft into reciprocating linear motion;
• the centre of gravity of the said mass being located directly over the said means for transmitting the forces generated by the said moving mass.

A system for non-destructive testing of the load bearing characteristics of a structure, said system comprising:

• an apparatus having a member (21) supported away from the surface (11) of the structure (10) to be tested by one or more supports (22, 24) in contact with the structure;
• measuring means (30) adapted to measure a quantity which varies with distance between the surface of the structure and a point on the said member remote from any of the said supports, said measuring means including
• an interferometer (32);
• reflecting means (34) which move responsively with deformations of the said surface, said reflecting means comprising a retroreflecting prism;
• said reflecting means and said interferometer together define at least one external optical path which varies with said quantity
• a probe (36) urged against the area of the structure to be tested, said probe supported so as to allow said probe to move responsively with deformations of the said area, the reflecting means being attached to said probe;
• and,
• means (40) for both applying a force on the structure and varying repetitively said force in a predetermined manner, at a location near the area to be tested.

A method for non-destructive testing of structures by measuring deformations to portions of a structure, said method comprising the steps of:

• applying a static load to a location of a structure (10) to be tested;
• replacing the load with a beam (21) suspended above the location to be tested, said beam supported by one or more supports (22, 24) resting on the structure remote from the location to be tested in such a manner so as to transmit to the said beam movements of the said structure proximate to the said supports;
• measuring repeatedly a quantity which varies with the distance between a portion of the said beam remote from the said supports and the said location to be tested as the location recovers the measuring step comprising:
• supporting reflecting means (34) which moves responsively with deformations to the location to be tested;
• utilizing an interferometer (32), in conjunction with said reflecting means, to measure the said quantity.

A method for non-destructive testing of structures by measuring deformations to portions of a structure, said method comprising the steps of:

• applying a static load to a location of a structure (10) to be tested;
• replacing the load with a beam (21) suspended above the location to be tested, said beam supported by one or more supports (22, 24) resting on the structure remote from the location to be tested in such a manner so as to transmit to the said beam movements of the said structure proximate to the said supports;
• measuring repeatedly a quantity which varies with the distance between a portion of the said beam remote from the said supports and the said location to be tested as the location recovers;
• and,
• comparing said measurements of deformation over time or as the static load applied to the structure varies.

A system for non-destructive testing of the load bearing characteristics of a structure, said system comprising:

• an apparatus having a member (21) supported away from the surface (11) of the structure (10) to be tested by being cantilevered from a single support in contact with the structure and measuring means (30) adapted to measure a quantity which varies with distance between the surface of the structure and a point on the said member remote from the said support, the measuring means including:
• an interferometer (32);
• reflecting means (34) which move responsively with deformations of the said surface;
• said reflecting means and said interferometer together define at least one external optical path which varies with said quantity;
• means (40) for both applying a force on the structure and varying repetitively said force in a predetermined manner, at a location near the area to be tested.

A system for non-destructive testing of the load bearing characteristics of a structure, said system comprising:

• an apparatus having a member (21) supported away from the surface (11) of the structure (10) to be tested by at least three supports (22, 24) in contact with the structure and measuring means (30) adapted to measure a quantity which varies with distance between the surface of the structure and a point on the said member remote from any of the said supports, the measuring means including:
• an interferometer (32);
• reflecting means (34) which move responsively with deformations of the said surface;
• said reflecting means and said interferometer together define at least one external optical path which varies with said quantity;
• means (40) for both applying a force on the structure and varying repetitively said force in a predetermined manner, at a location near the area to be tested.

A system for non-destructive testing of the load bearing characteristics of a structure, said system comprising:

• an apparatus having a member (21) supported away from the surface (11) of the structure (10) to be tested by one or more supports (22, 24) in contact with the structure and measuring means (30) supported by said member and adapted to measure a quantity which varies with distance between the surface of the structure and a point on the said member remote from any of the said supports, the measuring means including:
• an interferometer (32);
• reflecting means (34) which move responsively with deformations of the said surface;
• said reflecting means and said interferometer together define at least one external optical path which varies with said quantity;
• means (40) for both applying a force on the structure and varying repetitively said force in a predetermined manner, at a location near the area to be tested.