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Vibroakustisch wirksamer Zuschlagstoff

Granular aggregate mixed-in with building materials, especially concrete, comprises spheres containing compact mass surrounded by phase-change material having vibro-acoustic sensitivity
: Leistner, P.; Drotleff, H.

Frontpage ()

DE 102008059471 A: 20081128
DE 102008059471 A: 20081128
Patent, Elektronische Publikation
Fraunhofer IBP ()

(A1) Die Erfindung betrifft einen vibroakustisch wirksamen granularen Zuschlagstoff fuer Materialien, wie z.B. fuer Beton und aehnliche Baustoffe, bestehend aus einer aeusseren Huelle mit einer Fuellung aus mindestens einem mittels innerlich oder aeusserlich wirkender Felder, wie z.B. durch mechanische Spannungszustaende, akustische, elektrische oder magnetische Felder, schaltbarem Phasenwechselmaterial und mindestens einer darin eingebetteten kompakten Masse, die in dieser Fuellung je nach Aggregatzustand des Phasenwechselmaterials Schwingungen ausfuehrt, wodurch der mechanische Zustand des umgebenden Materials charakterisiert und das vibroakustische Verhalten des umgebenden Materials beeinflusst wird.


WO 2010060650 A2 UPAB: 20100614 NOVELTY - The granular aggregate consists of assemblies (2) containing a compact mass (4) in a material or composite (5) which can be solidified by mechanical action. This (5) is especially a phase-change material. Dependent on the degree of solidification, the compact mass (4) is able to execute oscillations. The phase-change material is enveloped by a casing (3). The shape of each granule is spherical and its mean diameter lies between a few tenths of a millimeter and a few millimeters. DETAILED DESCRIPTION - The construction of each spherical assembly enables excitation by oscillations at a resonant frequency. Membranes or partition walls are included in the sphere or casing. Solidification is dependent upon the frequency of oscillation acting on the material. The compact mass (4) is made from a material which can be excited into oscillation by electrical and/or magnetic fields. Various different materials capable of solidification may be included. The degree of solidification of the material (or composite material) is affected by external electrical- and/or magnetic fields. A component (1) made from building material containing the granules is also claimed. The mechanical state of the component influences the degree of solidification of the material (5)(or composite). Sudden alteration in the state of mechanical stressing of the component, especially caused by a micro-crack or other internal fracture mechanism, alters the degree of solidification of the material. The component is excited to oscillation and the reverberation-, ringing- and/or decay time is measured. Excitation is effected mechanically, acoustically, electrically and/or magnetically. The excitation is pulsed or harmonic. USE - A granular aggregate mixed-in with building materials, especially concrete. A method of detecting cracking, fatigue or other defects in load-bearing concrete components. The concrete component produced, is used in a situation requiring switchable sound attenuation and/or sound insulation (claimed). ADVANTAGE - Earlier methods of monitoring the mechanical integrity of concrete over the longer term, based on e.g. acoustic emission, were generally expensive and subject to complications, e.g. internal acoustic reflection. They required elaborate instrumentation, yet localization of defects was difficult. The new simple method allows non-destructive continuous monitoring and localization of defects in concrete component. Vibration causing stress, or caused by fracture propagation, is converted into degrees of solidification. Changes in solidification can be detected by low amplitude acoustic excitation. By forming a resonant system in the granules, spectral selectivity is achieved. Vibrations having no significance can be differentiated from those of special interest. The range of possible investigations is extended by use of material influenced by electrical and/or magnetic fields, instead of or in addition to acoustic fields. In a variant application, materials having switchable acoustic attenuation or insulation are produced. Further enhancements and refinements of the method are discussed in the text.