Ultrasonic Characterization of Symmetric Objects via Oblique Incidence
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Solution Overview
Problem
Current methods are unable to effectively determine the internal isotropy and mechanical characteristics such as Young's modulus and Poisson's ratio of small-sized parts with curved surfaces, like ball bearings, which are crucial for ensuring the reliability of these components.
Innovation Solution
A method involving the observation of ultrasound waves transmitted along an axis perpendicular to the plane of symmetry with an incidence different from normal, utilizing face-to-face transmission and reception ultrasonic transducers to measure the travel time of longitudinal, transverse, and Rayleigh waves, allowing for characterization of small objects and determining their mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional ultrasonic methods are used to characterize small parts, then the measurement capability is limited, but the ability to determine internal isotropy and mechanical characteristics of small parts with curved surfaces is insufficient
Solution Approach 1:
The patent introduces a new dimensional approach by utilizing Rayleigh surface waves that propagate along the curved surface of the part, in addition to bulk longitudinal and transverse waves. This multi-dimensional wave propagation approach enables characterization of small parts with curved surfaces by observing wave paths in multiple geometric dimensions, resolving the limitation of traditional single-path ultrasonic methods
Solution Approach 2:
The patent changes the wave propagation parameters by using oblique incidence angles (different from normal incidence) to generate mode conversions between longitudinal, transverse, and Rayleigh waves. This parameter change enables the extraction of multiple mechanical properties (Young's modulus, Poisson's ratio, internal isotropy) from a single measurement setup, significantly improving the versatility of characterizing small parts with curved surfaces
2Ease of operation
If ultrasonic waves strike the object at normal incidence, then the setup is simple, but additional information from mode conversion is not obtained
Solution Approach 1:
The patent uses oblique incidence angles that exceed the normal incidence condition, intentionally introducing additional complexity in wave path geometry to achieve mode conversion. This excessive action (using non-normal angles) generates longitudinal, transverse, and Rayleigh waves simultaneously, providing comprehensive material characterization information that compensates for the increased measurement complexity
Solution Approach 2:
The patent uses the curved surface of the part as an intermediary that facilitates mode conversion when ultrasonic waves strike at oblique angles. The surface acts as a mediator that transforms incident longitudinal waves into a combination of reflected longitudinal waves, transverse waves, and Rayleigh surface waves, enabling information extraction about multiple material properties without requiring separate measurement setups
3Device complexity
If only transmitted or reflected waves are observed, then the measurement is straightforward, but surface treatment detection capability is limited
Solution Approach 1:
The patent utilizes Rayleigh surface waves that propagate along the external surface of the part, which are highly sensitive to surface conditions and treatments. By observing the characteristics of these surface waves (velocity, attenuation, frequency content), the method can detect surface treatments such as nitriding, carburizing, or coating applications, providing reliable quality assurance for small parts with curved surfaces
Solution Approach 2:
The patent effectively creates a composite measurement approach by combining observations of bulk waves (longitudinal and transverse) with surface waves (Rayleigh waves). This composite wave observation strategy enables simultaneous determination of bulk material properties (internal isotropy, Young's modulus, Poisson's ratio) and surface properties (surface treatment presence and characteristics), comprehensively addressing both interior and exterior quality requirements
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables the characterization of small objects by providing additional information through mode conversion, facilitating the determination of mechanical properties like Young's modulus and Poisson's ratio, and detecting surface treatments, thus ensuring the reliability of components like ball bearings.
Implementation Method 1
The fact that the ultrasound waves strike the object at an angle different from normal allows the object's surface to be used as a mode conversion tool (body or surface waves)
Implementation Method 2
Each observation follows an emission of ultrasound waves striking the object along said axis at an angle of incidence different from the normal
Implementation Method 3
Analyzing the travel time of the ultrasound wave allows the object, whether small or large, to be characterized
Implementation Method 4
Document EP1767898 discloses the use of the Rayleigh wave, which is a surface wave produced on the surface of a part exposed to an incident ultrasonic wave
Implementation Method 5
Ultrasonic transmitters and detector transducers positioned coaxially are moved while observing ultrasound transmitted by the cylinder
Data Source
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AI summary
The invention concerns a method for characterising an object (300) comprising, at least locally, a plane of symmetry (PI), the method comprising at least one observation of ultrasound emitted by said object, each observation being carried out on an axis (d) perpendicular to the plane of symmetry (PI), each observation following an ultrasound emission generated respectively according to said axis (d) and meeting the object (300) along said axis (d) with an angle of incidence (-1) different from the normal, the ultrasound meeting the object (300) in such a way as to follow a path symmetrical to the plane of symmetry (PI).