giải đoán & đánh giá

GIẢI ĐOÁN & ĐÁNH GIÁ GIẢI ĐOÁN & ĐÁNH GIÁ  NGUYÊN TẮC CHUNG NGUYÊN TẮC CHUNG  GIẢI ĐOÁN VÀ ĐÁNH GIÁ BẰNG KỸ GIẢI ĐOÁN VÀ ĐÁNH GIÁ BẰNG KỸ THUẬT XUNG - TIẾNG VỌNG THUẬT XUNG - TIẾNG VỌNG NGUYÊN TẮC CHUNG NGUYÊN TẮC CHUNG  determination of basic ultrasonic parameters (echo height, time of flight);  determination of its basic shape and orientation  sizing: – measurement of one or more dimensions (or measurement of one or more dimensions (or area/volume), within the limitations of the methods; area/volume), within the limitations of the methods; – measurement of some agreed parameter e.g. echo measurement of some agreed parameter e.g. echo height height NGUYÊN TẮC CHUNG NGUYÊN TẮC CHUNG  location discontinuities  determination of any other parameters or characteristics that may be necessary for complete evaluation  assessment of probable nature, e.g. crack or inclusion GIẢI ĐOÁN VÀ ĐÁNH GIÁ BẰNG GIẢI ĐOÁN VÀ ĐÁNH GIÁ BẰNG KỸ THUẬT XUNG - TIẾNG VỌNG KỸ THUẬT XUNG - TIẾNG VỌNG  Location of discontinuity  Orientation of discontinuity  Assessment of multiple indications  Shape of discontinuity  Maximum echo height of indication  Size of discontinuity XÁC ĐỊNH VỊ TRÍ KHUYẾT TẬT XÁC ĐỊNH VỊ TRÍ KHUYẾT TẬT  reference to the index point and beam angle of the probe,  measurement of the probe position and beam path length at which the maximum echo height is observed. XÁC ĐỊNH HƯỚNG KHUYẾT TẬT XÁC ĐỊNH HƯỚNG KHUYẾT TẬT  The orientation of a discontinuity is the direction or plane along which the discontinuity has its major axis with respect to a datum reference on the test object.  determined from observation of the difference beam angles and/or scanning directions at which the maximum echo height is obtained  May not required in several applications ĐÁNH GIÁ CHỈ THỊ PHỨC TẠP ĐÁNH GIÁ CHỈ THỊ PHỨC TẠP  The qualitative determination consists of ascertaining whether or not such indications correspond to one or more separate discontinuities CH TH BLT PHAÂN GI I T TỈ Ị Ả Ố CH TH BLT PHỈ Ị ÂN GI I KEÙMẢ ĐÁNH GIÁ CHỈ THỊ PHỨC TẠP ĐÁNH GIÁ CHỈ THỊ PHỨC TẠP  determine whether the echoes arise from a series of closely spaced but separate discontinuities, or from a single continuous discontinuity having a number of separate reflecting facets, using the following techniques – Lateral/dọc characterisation Lateral/dọc characterisation – Transverse/ngang (Through-thickness) characterisation Transverse/ngang (Through-thickness) characterisation – Shadow technique/Kỹ thuật bóng(truyền qua) Shadow technique/Kỹ thuật bóng(truyền qua) ĐÁNH GIÁ CHỈ THỊ PHỨC TẠP ĐÁNH GIÁ CHỈ THỊ PHỨC TẠP  Lateral characterisation – For discontinuities showing a single, sharp indication For discontinuities showing a single, sharp indication – Use the narrowest practical beam width at the distance of the Use the narrowest practical beam width at the distance of the discontinuity, and a careful lateral scan under uniform discontinuity, and a careful lateral scan under uniform coupling conditions. coupling conditions. – noting that the echo height falls rapidly about the normal and noting that the echo height falls rapidly about the normal and that no significant secondary echoes are observed that no significant secondary echoes are observed – dips in the echo height envelope along its length means that dips in the echo height envelope along its length means that the discontinuity is intermittent This should be confirmed by the discontinuity is intermittent This should be confirmed by carrying out swivel and orbital scans adjacent to the apparent carrying out swivel and orbital scans adjacent to the apparent breaks breaks ĐÁNH GIÁ CHỈ THỊ PHỨC TẠP ĐÁNH GIÁ CHỈ THỊ PHỨC TẠP Transverse (through-thickness) characterisation – Careful transverse scans across the discontinuity from at least Careful transverse scans across the discontinuity from at least two directions at short sound path ranges two directions at short sound path ranges – The form of the echo envelope shall be noted (nghiên cứu The form of the echo envelope shall be noted (nghiên cứu sau) sau) – Significant dips or complete breaks in the echo envelope Significant dips or complete breaks in the echo envelope suggest that the discontinuity may be intermittent suggest that the discontinuity may be intermittent – Where access permits, a composite through-thickness picture Where access permits, a composite through-thickness picture of the discontinuity may be built up by plotting all the echoes of the discontinuity may be built up by plotting all the echoes observed from a number of different directions and angles. observed from a number of different directions and angles. [...]...ĐÁNH GIÁ CHỈ THỊ PHỨC TẠP Shadow technique 1: Transmission signal 2: A-scan 3: Intermittent discontinuity 4: No transmitted signal 5: Continuous discontinuity ĐÁNH GIÁ CHỈ THỊ PHỨC TẠP Shadow technique  Useful when the dimensions of the discontinuity, or group of discontinuities, are... angles (high directional reflectivity) is likely to be a large smooth reflector lying perpendicular to the beam angle at which the maximum echo height was observed TỔNG HỢP DỮ LIỆU CHỌN PHƯƠNG PHÁP ĐÁNH GIÁ ĐỘ LỚN KHUYẾT TẬT  maximum echo height techniques may be applied only if the dimension to be measured is less than the 6 dB beam width of the probe  fixed amplitude level techniques may be applied... dimension is greater than the beam width at the same dB drop If this condition is not fulfilled, the dimension of the discontinuity shall be assumed to be equal to the applicable beam width CHỌN PHƯƠNG PHÁP ĐÁNH GIÁ ĐỘ LỚN KHUYẾT TẬT(TT)  techniques based on positioning the individual edges of a discontinuity can only be applied when the ultrasonic indication from the discontinuity shows two or more resolvable . GIẢI ĐOÁN & ĐÁNH GIÁ GIẢI ĐOÁN & ĐÁNH GIÁ  NGUYÊN TẮC CHUNG NGUYÊN TẮC CHUNG  GIẢI ĐOÁN VÀ ĐÁNH GIÁ BẰNG KỸ GIẢI ĐOÁN VÀ ĐÁNH GIÁ BẰNG KỸ THUẬT XUNG. complete evaluation  assessment of probable nature, e.g. crack or inclusion GIẢI ĐOÁN VÀ ĐÁNH GIÁ BẰNG GIẢI ĐOÁN VÀ ĐÁNH GIÁ BẰNG KỸ THUẬT XUNG - TIẾNG VỌNG KỸ THUẬT XUNG - TIẾNG VỌNG  Location. ĐÁNH GIÁ CHỈ THỊ PHỨC TẠP ĐÁNH GIÁ CHỈ THỊ PHỨC TẠP Shadow technique 1: Transmission signal 2: A-scan 3: Intermittent discontinuity 4: No transmitted signal 5: Continuous discontinuity ĐÁNH