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International standards in NDT
INTERNATIONAL
STANDARDS
IN N D T
Fifty delegates from 12 countries attended the f i r s t plenary meeting of the new LSO Committee (ISO/TC 135) for n o n - d e s t r u c t i v e testing, held in London f r o m 21 to 23 September, 1970. O b s e r v e r s from the I n t e r national Institute of Welding (IIW), International E l e c t r o t e c h n i c a i C o m m i s s i o n (IEC) and f r o m other ISO C o m m i t t e e s having an i n t e r e s t in this subject were also present. The Chairman for this f i r s t meeting was Mr Colin Bates, Consultant, who is a prominent m e m b e r of BSI c o m m i t t e e s concerned with ndt and who c h a i r s the UK steering committee for this international work. Bearing in mind that international work on certain aspects of ndt was already being c a r r i e d out, the new Technical Committee carefully defined the o v e r all scope of its work to cover ndt as applied g e n e r a l ly to constructional m a t e r i a l s , components and a s semblies. Technical Committee 135 will not be concerned with quality levels, however, which a r e the responsibility of applications committees, nor with developing specific technical applications for p a r t i c u lar product f o r m s and components unless so r e quested by other ISO Committees. To c a r r y out its planned p r o g r a m m e of work, TC 135 set up the following Sub-committees:
Sub-committee Sub-committee Sub-committee Sub-committee
I: Terminology (France) 2: Surface methods (United Kingdom) 3: Acoustical methods (USA) 4: Electrical and magnetic methods (Italy) Sub-committee 5: Radiation methods (Germany) Sub-committee 6: Leak detection methods (France)
F o r co-ordinating the activities of the above Subcommittees, p a r t i c u l a r l y as r e g a r d s the p r e s e n t a tion and translation of documents, a Working Group was set up with the United Kingdom as its S e c r e t a r i a t . Within their fields of work, the S u b - c o m m i t t e e s will determine their p r i o r i t i e s for p r e p a r i n g documents defining methods of test and specifications relating to the testing equipment required, close liaison being maintained with Sub-committee 1 where terminology is concerned. P a r t i c u l a r i m p o r t a n c e is attached to the development of a g l o s s a r y for ndt and also to achieving international a g r e e m e n t concerning the p e r f o r m a n c e of testing equipment and m a t e r i a l s . It is also intended to provide guidance on the way in which ndt r e q u i r e m e n t s should be specified. The Committee will establish liaison with other ISO C o m m i t t e e s and other international organizations having a d i r e c t i n t e r e s t in this important and developing field of work. British Standards Institution, 2 P a r k Street, London W l A 2BS
RESEARCH AND DEVELOPMENT NDT OF ADHESIVE BOND STRENGTH Spin-off f r o m US space r e s e a r c h has led to the development of instrumentation for the ndt of adhesive bond strengths in honeycomb m a t e r i a l s . By inducing mechanical vibrations into the adhesive and observing the damping produced, it is possible to determine the bond strength. F r o m analytical and experimental work, a relationship was found between the variation in v i s c o - e l a s t i c p r o p e r t i e s of an adhesive. F r o m the adhesive damping data, it was predicted that the vibrational re ~ sponse amplitude would d e c r e a s e with elevated t e m p e r a t u r e s , and the relaxation c h a r a c t e r of the degraded adhesive would show a s m a l l activation energy. Two experimental test s y s t e m s were constructed. In the Displacement Oriented T r a n s d u c e r (DOT) s y s tem, vibrations a r e excited by an eddy c u r r e n t coil, and deflections ar,e m e a s u r e d with a photometric device. The other s y s t e m , based on a Laval nozzle siren, is designed to provide mechanical vibrations for non-metallic m a t e r i a l s . Analysis of the DOT vibration m e a s u r e m e n t s verified that the damping of the adhesive is related to the cohesive bond strength by either the internal friction at the fundamental and harmonic frequencies or the relative v i b r a t i o n - r e sponse peak amplitudes. Amplitude-response data a r e consistent with the mathematical analysis, show good c o r r e l a t i o n with cohesive bond strength, and are
in general a g r e e m e n t with the predicted damping theory and a d h e s i v e - p r o p e r t y tests. Thus, the DOT approach was shown to be a practical method of nondestructively determining cohesive bend strength. The development of a non-destructive test s y s t e m for m e a s u r i n g adhesive damping was directed toward a h i g h - e n e r g y excitation/detection t r a n s d u c e r s y s t e m for one-side bond-strength m e a s u r e m e n t s . A pneum a t i c - t y p e exciter was developed capable of p r o d u c ing air bursts up to 20, 000 pulses per second with f o r c e s of 0 . 4 - 1 . 3 N . Two a i r - p u l s e designs were completed and a l a b o r a t o r y test model was made using a Laval nozzle to produce a supersonic air flow to be chopped at a selectable frequency by a r o t a r y disk containing a s e r i e s of p e r i p h e r a l holes. The air pulser was evaluated as an alternative d r i v e r for bond-strength m e a s u r e m e n t s and proved sufficient for the r e q u i r e d high-level excitation. However, m o r e s a t i s f a c t o r y r e s u l t s were obtained in t e r m s of control and noise level using electromagnetic excitation. M e a s u r e m e n t s on composite specimens at various t e m p e r a t u r e s show a f r e q u e n c y / i n t e r n a l friction relationship which clearly indicates differences in cohesive bond strength. The internal friction data at some f r e q u e n c y / t e m p e r a t u r e conditions show the p r a c t i c a l i t y of g o / n o - g o indications and at other f r e q u e n c y / t e m p e r a t u r e conditions indicate a quantitative means of determining bend strength. F u r t h e r technical details are available at $ 3 . 0 0 f r o m the Clearinghouse for F e d e r a l Scientific, and Technical Information, Springfield, Virginia 22151, USA (quote r e f e r e n c e TSP69-10366) non-destructive testing D e c e m b e r 1970
393
STANDARDS
IN N D T
Fifty delegates from 12 countries attended the f i r s t plenary meeting of the new LSO Committee (ISO/TC 135) for n o n - d e s t r u c t i v e testing, held in London f r o m 21 to 23 September, 1970. O b s e r v e r s from the I n t e r national Institute of Welding (IIW), International E l e c t r o t e c h n i c a i C o m m i s s i o n (IEC) and f r o m other ISO C o m m i t t e e s having an i n t e r e s t in this subject were also present. The Chairman for this f i r s t meeting was Mr Colin Bates, Consultant, who is a prominent m e m b e r of BSI c o m m i t t e e s concerned with ndt and who c h a i r s the UK steering committee for this international work. Bearing in mind that international work on certain aspects of ndt was already being c a r r i e d out, the new Technical Committee carefully defined the o v e r all scope of its work to cover ndt as applied g e n e r a l ly to constructional m a t e r i a l s , components and a s semblies. Technical Committee 135 will not be concerned with quality levels, however, which a r e the responsibility of applications committees, nor with developing specific technical applications for p a r t i c u lar product f o r m s and components unless so r e quested by other ISO Committees. To c a r r y out its planned p r o g r a m m e of work, TC 135 set up the following Sub-committees:
Sub-committee Sub-committee Sub-committee Sub-committee
I: Terminology (France) 2: Surface methods (United Kingdom) 3: Acoustical methods (USA) 4: Electrical and magnetic methods (Italy) Sub-committee 5: Radiation methods (Germany) Sub-committee 6: Leak detection methods (France)
F o r co-ordinating the activities of the above Subcommittees, p a r t i c u l a r l y as r e g a r d s the p r e s e n t a tion and translation of documents, a Working Group was set up with the United Kingdom as its S e c r e t a r i a t . Within their fields of work, the S u b - c o m m i t t e e s will determine their p r i o r i t i e s for p r e p a r i n g documents defining methods of test and specifications relating to the testing equipment required, close liaison being maintained with Sub-committee 1 where terminology is concerned. P a r t i c u l a r i m p o r t a n c e is attached to the development of a g l o s s a r y for ndt and also to achieving international a g r e e m e n t concerning the p e r f o r m a n c e of testing equipment and m a t e r i a l s . It is also intended to provide guidance on the way in which ndt r e q u i r e m e n t s should be specified. The Committee will establish liaison with other ISO C o m m i t t e e s and other international organizations having a d i r e c t i n t e r e s t in this important and developing field of work. British Standards Institution, 2 P a r k Street, London W l A 2BS
RESEARCH AND DEVELOPMENT NDT OF ADHESIVE BOND STRENGTH Spin-off f r o m US space r e s e a r c h has led to the development of instrumentation for the ndt of adhesive bond strengths in honeycomb m a t e r i a l s . By inducing mechanical vibrations into the adhesive and observing the damping produced, it is possible to determine the bond strength. F r o m analytical and experimental work, a relationship was found between the variation in v i s c o - e l a s t i c p r o p e r t i e s of an adhesive. F r o m the adhesive damping data, it was predicted that the vibrational re ~ sponse amplitude would d e c r e a s e with elevated t e m p e r a t u r e s , and the relaxation c h a r a c t e r of the degraded adhesive would show a s m a l l activation energy. Two experimental test s y s t e m s were constructed. In the Displacement Oriented T r a n s d u c e r (DOT) s y s tem, vibrations a r e excited by an eddy c u r r e n t coil, and deflections ar,e m e a s u r e d with a photometric device. The other s y s t e m , based on a Laval nozzle siren, is designed to provide mechanical vibrations for non-metallic m a t e r i a l s . Analysis of the DOT vibration m e a s u r e m e n t s verified that the damping of the adhesive is related to the cohesive bond strength by either the internal friction at the fundamental and harmonic frequencies or the relative v i b r a t i o n - r e sponse peak amplitudes. Amplitude-response data a r e consistent with the mathematical analysis, show good c o r r e l a t i o n with cohesive bond strength, and are
in general a g r e e m e n t with the predicted damping theory and a d h e s i v e - p r o p e r t y tests. Thus, the DOT approach was shown to be a practical method of nondestructively determining cohesive bend strength. The development of a non-destructive test s y s t e m for m e a s u r i n g adhesive damping was directed toward a h i g h - e n e r g y excitation/detection t r a n s d u c e r s y s t e m for one-side bond-strength m e a s u r e m e n t s . A pneum a t i c - t y p e exciter was developed capable of p r o d u c ing air bursts up to 20, 000 pulses per second with f o r c e s of 0 . 4 - 1 . 3 N . Two a i r - p u l s e designs were completed and a l a b o r a t o r y test model was made using a Laval nozzle to produce a supersonic air flow to be chopped at a selectable frequency by a r o t a r y disk containing a s e r i e s of p e r i p h e r a l holes. The air pulser was evaluated as an alternative d r i v e r for bond-strength m e a s u r e m e n t s and proved sufficient for the r e q u i r e d high-level excitation. However, m o r e s a t i s f a c t o r y r e s u l t s were obtained in t e r m s of control and noise level using electromagnetic excitation. M e a s u r e m e n t s on composite specimens at various t e m p e r a t u r e s show a f r e q u e n c y / i n t e r n a l friction relationship which clearly indicates differences in cohesive bond strength. The internal friction data at some f r e q u e n c y / t e m p e r a t u r e conditions show the p r a c t i c a l i t y of g o / n o - g o indications and at other f r e q u e n c y / t e m p e r a t u r e conditions indicate a quantitative means of determining bend strength. F u r t h e r technical details are available at $ 3 . 0 0 f r o m the Clearinghouse for F e d e r a l Scientific, and Technical Information, Springfield, Virginia 22151, USA (quote r e f e r e n c e TSP69-10366) non-destructive testing D e c e m b e r 1970
393