Ultrasonic Testing Method Research Articles

Polymer Effects on the Vibration Damping Behavior of Cement

In this paper, the vibration damping properties of polymer-modified-cement (PMC) have been studied. The storage modulus (E′) and loss tangent (tan δ ) of PMC were studied by using a free vibration method. The propagation velocity of stress wave V and the scattered damping of stress wave in PMC were studied by using an ultrasonic testing method. When a suitable polymer is added in the cement, the storage modulus, the velocity of stress waves are decreased with an increase of the polymer/cement ratio (P/C), and the loss tangent is increased with an increase of P/C, thus the ability to vibration damping of PMC is improved. As the P/C is between 15 and 20%, the PMC demonstrates the best vibration damping within the adopted range of testing.

Residual stress analysis on heavy plates by ultrasonic testing

The heavy steel plates (100 - 300 mm) require a good geometric stability during the manufacturing operations by end users. This stability depends on the residual stress state inherited from the manufacturing process. This residual stress state is assessed by an ultrasonic testing method : the acoustical birefringence. The first tests carried out on representative heavy plates allowed to define the most suitable measurement configurations and to identify the residual stress states that could generate shape defects. Then, this method was applied to industrial heavy plates with success.

Indentation fracture toughness and dynamic elastic moduli for commercial feldspathic dental porcelain materials

Objective. The purpose of this study was to evaluate and compare the indentation fracture toughness, true hardness and dynamic elastic moduli for 14 commercial dental porcelain materials. Methods. The specimens were fired according to manufacturer instructions. The density of the specimens ( n=3) was measured by means of the water displacement technique. Dynamic Young's shear and bulk moduli and Poisson's ratio ( n=3) were measured using a non-destructive ultrasonic technique using 10 MHz lithium niobate crystals. The true hardness ( n=3) was measured using a Knoop indenter and the fracture toughness ( n=3) was determined using a Vickers indenter and a Tukon hardness tester. Statistical analysis of the data was conducted using ANOVA and a Student–Newman–Keuls (SNK) rank order multiple comparative test. Results. The SNK rank test analysis for the mean dynamic Young's modulus and fracture toughness was able to separate 14 dental porcelain materials into seven and nine groups, respectively, at p=0.05. The elastic moduli, true hardness and indentation fracture toughness for opaque porcelains were significantly higher than incisal; and body materials at p=0.05. Significance. The indentation fracture toughness and the ultrasonic test methods exhibit lower coefficient of variation compared to conventional methods and have considerable advantage for ceramic dental materials in that only small specimens are required to produce an acceptable number of data for statistical analysis.

Mechanical properties of commercial high strength ceramic core materials

Objective. The objective of the present study is to evaluate and compare the flexural strength, dynamic elastic moduli and true hardness ( H o) values of commercial Vita In-Ceram ® alumina core and Vita In-Ceram ® matrix glass with the standard aluminous porcelain (Hi-Ceram ® and Vitadur ®), Vitadur N ® and Dicor ® glass and glass-ceramic. Methods. The flexural strength was evaluated ( n=5) using 3-point loading and a servo hydraulic Instron testing machine at a cross head speed of 0.5 mm/min. The density of the specimens ( n=3) was measured by means of the water displacement technique. Dynamic Young's shear and bulk moduli and Poisson's ratio ( n=3) were measured using a non-destructive ultrasonic technique using 10 MHz lithium niobate crystals. The true hardness ( n=3) was measured using a Knoop indenter and the fracture toughness ( n=3) was determined using a Vickers indenter and a Tukon hardness tester. Statistical analysis of the data was conducted using ANOVA and a Student–Newman–Keuls (SNK) rank order multiple comparative test. Results. The SNK rank order test analysis of the mean flexural strength was able to separate five commercial core materials into three significant groups at p=0.05. Vita In-Ceram ® alumina and IPS Empress ® 2 exhibited significantly higher flexural strength than aluminous porcelains and IPS Empress ® at p=0.05. The dynamic elastic moduli and true hardness of Vita In-Ceram ® alumina core were significantly higher than the rest of the commercial ceramic core materials at p=0.05. Significance. The ultrasonic test method is a valuable mechanical characterization tool and was able to statistically discriminate between the chemical and structural differences within dental ceramic materials. Significant correlation was obtained between the dynamic Young's modulus and true hardness, p=0.05.

Rapid Inspection of Composite Skin-Honeycomb Core Structures with Ultrasonic Guided Waves

Guided wave inspection of composite skin-honeycomb core structures is an efficient and sensitive alternative to other common inspection methods. This paper shows that sweeping experimentally through the dispersion curves is an effective way to experimentally locate guided wave modes sensitive to skin-core delamination. Composite skin-Nomex honeycomb core specimens were developed with simulated delaminated areas. The delaminated areas were detected with guided waves and confirmed with conventional ultrasonic testing methods. Calculated phase velocity dispersion curves are given to define the practical phase velocity and frequency ranges. Example wave structures in this range are given to illustrate the change in sensitivity as frequency is swept for a given mode.

Mechanical properties of old concrete using destructive and ultrasonic non-destructive testing methods

This paper examines the variation in properties of a specific type of 28-year-old concrete, the characteristics of which were known at 7, 28, 36 and 90 days. Beyond the destructive tests (compression, splitting tension and bending), the concrete was studied with non-destructive ultrasound testing. Moreover, the relationship between the compressive strength of this concrete and the ultrasonic longitudinal wave velocity, as well as the dynamic modulus of elasticity were determined. The objective was to control changes in the quality of concrete over a long period of time and to contribute to the development of a non-destructive method for the determination of concrete strength in structures. The presented approach, that seems promising for such development, uses the velocity of ultrasonic waves in concrete.

Mechanical properties of old concrete using destructive and ultrasonic non-destructive testing methods

This paper examines the variation in properties of a specific type of 28-year-old concrete, the characteristics of which were known at 7, 28, 36 and 90 days. Beyond the destructive tests (compression, splitting tension and bending), the concrete was studied with non-destructive ultrasound testing. Moreover, the relationship between the compressive strength of this concrete and the ultrasonic longitudinal wave velocity, as well as the dynamic modulus of elasticity were determined. The objective was to control changes in the quality of concrete over a long period of time and to contribute to the development of a non-destructive method for the determination of concrete strength in structures. The presented approach, that seems promising for such development, uses the velocity of ultrasonic waves in concrete.

Dynamic properties impact toughness and abrasiveness of polymer-modified pastes by using nondestructive tests

This paper reports on the results of a study of the dynamic properties impact toughness and abrasiveness of polymer-modified pastes (PMPs) using a styrene–acrylic ester copolymer emulation. The dynamic elastic modulus E d and the specific damping capacity Y of PMP were studied using a free vibration method. The propagation velocity of stress wave V and the scattered damping of stress wave in PMP were studied using an ultrasonic testing method. The impact toughness and abrasiveness were also studied. The dynamic modulus and the velocity of stress wave decreased with an increase in polymer–cement ratio (P/C) by mass. The specific damping capacity, impact toughness, and abrasiveness increased with an increase in P/C, thereby improving the ability of PMP to resist dynamic loads. When P/C is 15–20%, PMP demonstrates the best dynamic behaviour within the adopted range of testing.

Estimation of the Reliability of Testing Welded Joints of Steam Pipelines of Thermal Power Plants

The problem of inspection of welded joints in the process of their longtime operation is considered. It is shown that it is advantageous to use the ultrasonic testing method in fabricating (mounting) steam pipelines. The microfailure rate must be tested in the process of operation. The period of the microfailure rate testing should be established on the basis of acting (calculated) stresses and the value of the longtime strength.

The split-method of ultrasonic nondestructive testing

This article describes a new method of echo-impulse ultrasonic testing based on a new “split-algorithm” for signal formation and processing. Application of a split-algorithm can significantly raise the sensitivity of testing devices (by two–three or more orders) while avoiding the loss of resolving capacity. Experimental results prove the practical importance of split-algorithms. Due to its high sensitivity, the proposed flaw detection method can be used to test objects with high absorption of ultrasound.

Development of Methods of Ultrasonic Nondestructive Testing of Welded Joints

The methods of ultrasonic nondestructive testing of welded joints used in Russia are reviewed. The ways of testing the reliability of the testing results are discussed.

Through Thickness Ultrasonic Testing and Its Use in Characterising the Mechanical Properties of Various Types of Limestone

The stiffness coefficients of different types of limestone were determined using the through thickness ultrasonic test and measurements of size and weight, and the results obtained verified using aluminium specimens of known mechanical properties. The values of density and stiffness coefficients obtained for the various types of limestone were consistent with their different formation processes. The stiffness coefficients for each specimen were different, exhibited directional properties and were significantly lower in one of the three mutually orthogonal directions in which tests were conducted, a clear confirmation of the heterogeneous and layered nature of limestone. Clearly, therefore, while the through thickness ultrasonic test easily yielded through thickness values of stiffness coefficient, complete characterisation of limestone, would require the use of more complex ultrasonic testing equipment and methods. (Journal of Civil Engineering, JKUAT: 2002 8: 99-110)

Characterization of silane coated hollow sphere alumina-reinforced ultra high molecular weight polyethylene composite as a possible bone substitute material

Silane coated hollow sphere alumina ceramic particles were moulded with ultra high molecular weight polyethylene (UHMWPE) to form a series of composites with alumina weight percent in the range from 15 to 50. The composites were prepared in a cylindrical mould using powder-processing technique. The composites were characterized for mechanical properties using destructive and non-destructive ultrasonic testing methods. The physical properties of the composite were determined and compared with those of cortical bone.

Evaluation of giga‐cycle fatigue properties of some maraging steels by intermittent ultrasonic fatigue testing

ABSTRACT In evaluating the giga‐cycle fatigue strength of some high strength steels, information on the size distribution of nonmetallic inclusions contained in the material is indispensable. To save time and effort of obtaining such data concerning the inclusions, a convenient dissolution method to evaluate the maximum inclusion size is proposed, in place of a conventional method of measuring the inclusion sizes on many cross‐sectional areas. Meanwhile, to save time‐consuming work of obtaining giga‐cycle fatigue properties of some metallic materials, an intermittent ultrasonic fatigue testing method has also been developed. In the present paper, these two newly developed methods were successfully combined to assess the long life fatigue properties of maraging steels as a function of inclusion size.

Theoretical elucidation on the empirical formulae for the ultrasonic testing method for concrete structures

The main purpose of this paper was to theoretically elucidate the compressive strength of concrete using the empirical formula with exponential form for the ultrasonic testing method through a generalization of the one-dimensional wave equation. The approximate solutions derived from a generalization of the one-dimensional wave propagation theory using the separation of variables method can be represented as the exponential form. If the viscosity of the concrete materials in stress wave method is neglected, the elastic waves can then be reduced to the ultrasonic waves. Through the membership function concept in the fuzzy set theory, the approximate solution with exponential form can be represented as the empirical formulae for the ultrasonic testing method in predicting the compressive strength of concrete. This present study indicates that both the ultrasonic pulse velocity (UPV) and ultrasonic pulse amplitude (UPA) methods are just a special case of the combined method. The predicted results of the combined method are actually better than the results obtained from either the UPV or UPA method.

The development of the welding process for the long length CICC jacket production

The jacket of ITER superconducting cable-in-conduit conductors (CICC) for TF coil insert is made by butt welding of short length (6-10 m) thin walled circular tubes. The outer diameters of tubes are 41-51 mm. Material of tubes - Incoloy-908 and titanium BT1-0. Method of welding - orbital gas tungsten arc welding. The special complex program of investigation was prepared. The influences of the different technological factors (tube edge preparing, compaction, bending, heat treatment) and operating conditions (temperature from 273 to 4.2 K, pressure up to 2 MPa) upon the welding joint properties were investigated. The samples were produced using different technological parameters. It is desirable to receive the welding joints properties close to the properties of base material of tubes. The microstructure of welding joints and their mechanical properties were investigated. The quality of welding joints was evaluated by dimensional, X-rays, ultrasonic, pressure and leak testing methods. Incoloy-908 and titanium are strong gas getters and elaborate methods of protection were used.

Automatic Potato Sorting System in Underwater Ultrasonic Instrumentation

The objectives of this study were to evaluate produce quality non-destructively by employing underwater ultrasonic testing method without pressing ultrasonic probes against produce and study the feasibility of developing an underwater ultrasonic sorting machine for produce. LabVIEW, a graphical programming software was adopted in the acquisition of ultrasonic signals, calculation of spectral moment, and building functions for classifying potatoes. The output result from running the program was adopted to control the potato sorting mechanism.

Neural classification of Lamb wave ultrasonic weld testing signals using wavelet coefficients

This paper presents an ultrasonic nondestructive weld testing method based on the wavelet transform (WT) of inspection signals and their classification by a neural network (NN). The use of Lamb waves generated by an electromagnetic acoustic transducer (EMAT) as a probe allows us to test metallic welds. In this work, the case of an aluminum weld is treated. The feature extraction is made by using a method of analysis based on the WT of the ultrasonic testing signals; a classification process of the features based on a neural classifier to interpret the results in terms of weld quality concludes the process. The aim of this complete process of analysis and classification of the testing ultrasonic signals is to lead to an automated system of weld or structure testing. Results of real-world ultrasonic Lamb wave signal analysis and classifications for an aluminum weld are presented; these demonstrate the feasibility and efficiency of the proposed method.

Evaluation of Tensile Strength of Partial Penetration Butt Welded Joints by Ultrasonic Testing

Partial penetration butt welded joints are widely used because they require relatively less weld metal for fabrication. However, incomplete penetration acts as a crack-like flaw. When the size of flaw in a material is known, the tensile strength of the material can be evaluated using fracture mechanics. This paper deals with a practical method of estimating the size of flaw (the incomplete penetration of a partial penetration butt welded joint) by ultrasonic testing (UT). The refraction angle of the probe and the method of UT are discussed. In addition, tensile strengths of welded joints are evaluated using fracture mechanics, and are found to be in good agreement with experimental results.

Determination of the Optimum Directional Angles of Ultrasonic Oscillation in Testing Seamless Thick-Wall Pipes

A method is proposed for determining the optimum angles at which ultrasonic waves must be directed in the pipe body for the purpose of testing the pipe quality by means of the ultrasonic test method that employs shear waves propagating in the pipe wall along a zigzag trajectory perpendicularly to the generatrix.