Arresting material test apparatus and methods
First Claim
1. Arresting material test apparatus, to test compressive gradient strength on a continuous basis from the surface to an internal depth of penetration within compressible arresting material, comprising:
- a penetration shaft having a length greater than said internal depth of penetration and a cross-sectional size;
a test probe head connected to said penetration shaft and having a compressive contact surface;
said penetration shaft including a constricted shaft portion beginning behind said test probe head and continuing for at least a part of said length, said constricted shaft portion having a cross-sectional area smaller than the area of said contact surface of said test probe;
a drive mechanism coupled to said penetration shaft to displace said shaft to drive said test probe head to said internal depth of penetration within arresting material;
a displacement sensing device coupled to said penetration shaft to sense displacement thereof;
a load sensing device coupled to said penetration shaft to sense the force exerted against said test probe contact surface as it compresses arresting material to said internal depth of penetration; and
a data acquisition device responsive to force sensed by said load sensing device and to the depth of penetration of said test probe contact surface to provide data representative of compressive gradient strength of said compressible arresting material to said depth of penetration.
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0 Petitions
Accused Products
Abstract
Arresting material test apparatus, test probes and test methods enable testing of compressive gradient strength of cellular concrete, and materials having similar characteristics, on a continuous basis from the surface of a section to a typical internal penetration depth of at least 60 percent of thickness. Previous testing of cellular concrete typically focused on testing to confirm a minimum structural strength prior to structural failure or shattering of a test sample. For an aircraft arresting bed, for example, cellular concrete must exhibit a compressive gradient strength in a relatively narrow precalculated range continuously from the surface to penetration depth equal to 60 to 80 percent of sample thickness. Precalculated and controlled compressive gradient strength is critical to enabling an aircraft to be safely stopped within a set distance, without giving rise to drag forces exceeding main landing gear structural limits. New test apparatus, test probes with post-compression build-up relief and test methods are described to enable such testing and recordation of data showing the gradient of compressive strength as it increases from the surface of a test sample to a predetermined depth of penetration. Resulting compressive gradient strength data is representative of performance of cellular concrete sections in decelerating an aircraft.
42 Citations
34 Claims
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1. Arresting material test apparatus, to test compressive gradient strength on a continuous basis from the surface to an internal depth of penetration within compressible arresting material, comprising:
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a penetration shaft having a length greater than said internal depth of penetration and a cross-sectional size; a test probe head connected to said penetration shaft and having a compressive contact surface; said penetration shaft including a constricted shaft portion beginning behind said test probe head and continuing for at least a part of said length, said constricted shaft portion having a cross-sectional area smaller than the area of said contact surface of said test probe; a drive mechanism coupled to said penetration shaft to displace said shaft to drive said test probe head to said internal depth of penetration within arresting material; a displacement sensing device coupled to said penetration shaft to sense displacement thereof; a load sensing device coupled to said penetration shaft to sense the force exerted against said test probe contact surface as it compresses arresting material to said internal depth of penetration; and a data acquisition device responsive to force sensed by said load sensing device and to the depth of penetration of said test probe contact surface to provide data representative of compressive gradient strength of said compressible arresting material to said depth of penetration. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An arresting material test probe, suitable to test compressive gradient strength continuously from the surface to an internal depth of penetration within compressible arresting material, comprising:
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a penetration shaft having a length not less than said internal depth of penetration and a cross-sectional size; and a test probe head connected to said penetration shaft and having a compressive contact surface; said penetration shaft including a constricted shaft portion, beginning behind said test probe head and continuing for at least a part of said length, said constricted shaft portion having a smaller cross-sectional area than the area of said contact surface of said test probe; the smaller cross-sectional area of said constricted shaft portion being effective to reduce distortive effects of post-compression build-up of material behind said contact surface as it travels from the surface to said internal depth of penetration within compressible arresting material under test, and the combination of said compressive contact surface and smaller cross-sectional area of said constricted shaft portion being effective to enable determination of compressive gradient strength over said depth of penetration within a section of compressible arresting material to be tested. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A method for continuous compressive testing of a cellular concrete section suitable for arresting motion of an object, comprising the steps of:
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(a) providing a penetration shaft bearing a test probe head with a compressive contact surface having a contact surface area; (b) providing a test section of cellular concrete having a thickness and having a cross-sectional area larger than said contact surface area; (c) supporting said test section longitudinally; (d) driving said contact surface of said test probe head longitudinally into said test section from a surface to an internal depth of penetration within said test section; (e) monitoring displacement of said test probe head; and (f) monitoring compressive force on said contact surface at a plurality of intermediate depths of penetration within said test section. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A method for determining compressive gradient strength over a depth of penetration of a test section, comprising the steps of:
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(a) driving a contact surface into said test section to an internal depth of penetration within said test section equal to at least 60 percent of the thickness of said test section; (b) during step (a), recording a measure of compressive force on said contact surface for a plurality of intermediate depths of penetration within said test section; and (c) making available a presentation of a gradient representing values of compressive force at said plurality of intermediate depths of penetration. - View Dependent Claims (28, 29)
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30. A method for determining compressive gradient strength over a depth of penetration of a test section of compressible material, comprising the steps of:
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(a) driving a flat contact surface into said test section to compress said compressible material from a surface to an internal depth of penetration within said test section; (b) during compression in step (a), recording a measure of compressive force on said contact surface for a plurality of intermediate depths of penetration within said test section; and (c) making available a presentation of compressive gradient strength representing values of compressive force at said plurality of intermediate depths of penetration during compression of said compressible material. - View Dependent Claims (31, 32, 33, 34)
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Specification