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Austenitic stainless Fe-0.1C-16Cr-13Ni-2Mo (wt. %) steel was subjected to cold swaging with strain ≤95%. In the cross-section of the cold-swaged bar, the gradient structure was observed. The dynamic mechanical behavior of the program steel was studied by the Charpy V-notch impact testing at room temperature. It was found that impact toughness and impact plane-strain fracture toughness (KId) decreased dramatically after a 20% swaging reduction. In the reduction range of 20-95%, stabilization of impact toughness and impact plane-strain fracture toughness was derived at the level of 0.6-0.8 MJ/m2 and 71-83 MPa×m1/2, respectively. Meanwhile, the stress at general yield (σye) and maximum stress (σm) increased with swaging reduction. The fracture surfaces of specimens after Charpy V-notch impact testing were examined. [ABSTRACT FROM AUTHOR]

Stress concentrations arise at welded joints due to local notches at weld transitions and determine fatigue life under cyclic loading. In order to accurately determine the severity of these stress concentrations from local weld geometry parameters advanced measurement technologies are required; however, the characterization of welded joints is traditionally based on manual measurements. In recent years, several techniques have been developed to characterize geometrical and stress concentration features of welded joints. This study briefly reviews a number of studies on weld geometry measurements, stress concentration characterization, and the determination of their influence on fatigue life estimation. Finally, an outlook on machine learning-based determination of fatigue life is given. [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced polymers (CFRP)and Glass fiber reinforced polymers(GFRP)are widely used in civil, mechanical and aerodynamic structures for providing additional strength to existing components. Polymers may be used directly or may be applied as a layer to other materials. Vibration analysis of undamaged and damaged GFRP beam was performed in this work. Damage to the GFRP specimen is introduced as a single rectangular notch and as a combination of a single rectangular notch with a curved edge and a double rectangular notch closer to the fixed end. With the support of Fast Fourier Transform (FFT), natural frequency is obtained by converting a time domain signal into a frequency domain signal. A comparison is made with the experimentally measured natural frequency for both the type of damage and the different positions of the accelerometer. The experiments presented in this study illustrates changes in natural frequencies indicate damage in GFRP cantilever beams and Frequency Response Functions (FRFs) envelope attained by experimental tests, Natural frequencies obtained numerically using ANSYS are also compared with natural frequencies from experiments. [ABSTRACT FROM AUTHOR]

The type of material is one of the basic requirements for an automotive design. With the various needs of mechanical properties, the types of material are different. Charpy Impact Test is a method that can be used to measure the strength, toughness and ductility of a material. This study is aimed to determine the value of the impact energy and stress with variations of impactor velocity (2 m/s, 2.5 m/s and 3 m/s), the notch on the specimen (v, u and keyhole), impactor's mass (1 kg, 1.5 kg and 2 kg). This research uses finite element method software to develop the models. From the simulation's results, the value of the stress and impact energy obtained is various, namely, the maximum stress of v notch is 369.7 MPa at an impactor velocity of 3 m/s and impactor's mass of 2 kg, the maximum stress of u notch is 371.9 MPa at an impactor velocity of 3 m/s and impactor's mass of 1.5 kg, and the maximum stress of keyhole notch is 370.8 MPa at an Impactor velocity of 3 m/s and impactor's mass of 2 kg. The maximum impact energy for 0.179 J/mm2 at keyhole notch with impactor velocity of 3 m/s and impactor's mass of 2 kg. Therefore, the most difficult model to break is the model with a keyhole notch because it has higher toughness. [ABSTRACT FROM AUTHOR]

The use of the bimetal and fiber-metal laminates principle has contributed to increasing the material's mechanical strength. This study discusses the comparison of the mechanical strength (stress, strain, and safety factor) of bimetal SPCC- AL 6061 T6 with fiber-metal SPCC-Epoxy Carbon UD (230 GPa) Prepreg through the Impact testing method analyzed by FEM using ANSYS Explicit Dynamic. This test is carried out according to the Charpy test standard on ASTM E23 with type A, type B, and type C impact specimens. The variable speed of the striker used is 0.3 m/s; 0.6 m/s; 1 m/s; 2 m/s. Apart from the aforementioned speeds, an analysis was also carried out to find the impact velocity limit for each specimen. This speed limit is the speed at which the safety factor value is 1. The different bimetal material and notch designs show different behavior that tends to a different result. From the simulation, it was found that SPCC-AL 6061 T6 Type A has better mechanical strength than others with a higher speed limit, smaller maximum stress, smaller maximum strain, and higher safety values at the same speed. [ABSTRACT FROM AUTHOR]

The presence of notch in engineering components influences mechanical properties of material. Notch is one source of stress concentration, which reduces material strength. In this paper, the Von mises stress, safety factor, and displacement of different geometry of notched specimens has been studied. Simulation based analysis was applied on 10 specimens contain trapezoidal shaped notch made of SPCC material with variation in angle of the notch geometry under tension loading. The tension testing was carried out by following ASTM E8M guidelines and applied for the basic dimension of specimens. The results were compared in order to determine load behavior of notched specimens related to angle presented in the notch geometry. Surprisingly, the data of Von mises stress and safety factor gain from increasing angle in trapezoidal notch indicate some fluctuations, and the causes were then discussed. Stress distribution during tension loading is concentrated on the sharp area around notch-tip, so the crack can be triggered. [ABSTRACT FROM AUTHOR]

Nowadays, the automotive industry aims to develop lighter vehicles, especially EVs. Thus, lightweight alloys such as aluminum sheets have been increasingly used to make various automotive panels. In this work, effects of material anisotropy on forming limit behaviour of AA5052-H32 aluminum sheet were investigated. Tensile tests of samples having different notch geometries as well as stretch-forming tests of Marciniak samples were carried out for obtaining the fracture forming limit curve (FFLC). In addition, sample orientations with regard to the rolling direction were considered by the formability analysis. The resulted anisotropic FFLCs of investigated sheets were compared and discussed. Finally, experiments and FE simulations of a cross-die forming test were carried out. The Hill'48 yield criterion and Swift hardening law were applied to describe the anisotropic plastic deformation. Then, failure occurrences of formed part were predicted by the FFLCs taking into account the material anisotropy. It was found that the proposed FFLCs could more precisely describe the formability of the examined aluminum sheet than the conventional FFLC. [ABSTRACT FROM AUTHOR]

Solar air heaters generally exhibit lower levels of thermal performance due to thermal losses and poor heat transfer characteristics of air. One of the commonly used techniques for performance improvement is to enhance turbulence levels in the flowing air stream. This paper presents the computational fluid dynamics analysis on the influence of trapezoidal rib shape factor and notch on the overall thermal behavior of solar air heater at constant heat flux conditions. The simulation is conducted for different Reynolds number varying from 11000 to 25000. The rib shape factor is varied as 1.71-8.85 for a fixed rib height value of 1.4 mm. The results reveal that lower values of shape factor improve heat transfer by about 13.1% for the rib shape factor of 2.42 while lower values of shape factor produce increased pressure drop by about 31% on an average for the rib shape factor of 1.71. The presence of notches create additional peak Nusselt number locations which however is negated by the presence of entrapped smaller eddies which effectively result in marginal improvement in heat transfer relative to the notchless rib irrespective of the geometry of notch. It is concluded that the suitable design modification of notches is essential to overcome the hot spots in order to take advantage of the concept of notch on ribs to achieve improved thermal characteristics. [ABSTRACT FROM AUTHOR]

The paper presents a next stage in the development of excitable cellular automata method which allows one to model energy flow propagation in a loaded solid under external mechanical and thermal-dynamic loads. At this stage the method is proposed for assessing the probability of crack initiation near geometric stress concentrators. Patterns of various mechanical characteristics distribution on the specimen surfaces are given, as well as the time dependence graphs of the average values of these parameters in the vicinity of notch tip. Some aspects of the notch shape effect over the deformation patterns as well as prospects of the proposed approach development are discussed. [ABSTRACT FROM AUTHOR]

Recent work has demonstrated the capability of applying inverse methods to automated eddy current (EC) data of surface breaking cracks and notches of various sizes, orientations and aspect ratios. However, not all eddy current indications in turbine engine component inspections originate from cracks, which can result in the unnecessary removal of engine components from service. For powder metallurgy nickel-based superalloys, non-metallic inclusions (NMIs) and non-metallic particles are frequently present. If an EC inspection can reliably classify NMI indications from crack indications, there would be great payoff for the USAF. In this work, simulated results are presented to highlight differences in eddy current signals from cracks and NMIs. Progress is presented on the development of a new model-based inversion scheme highlighting enhancements to the numerical model VIC-3D®, improved indication registration in noisy scans, and the fitting and evaluation of multiple surrogate model classes. Lastly, inversion results demonstrate the ability to distinguish cracks and NMIs, and the potential to characterize the approximate dimensions and depth of NMIs. [ABSTRACT FROM AUTHOR]

The fracture toughness characteristics of ZrO2ceramics were determined experimentally using an original technique of wedging small-sized chevron notch specimens developed at the Institute of Strength Physics and Materials Science SB RAS (Russia) in the laboratory of physical mesomechanics of materials and non-destructive testing. Measurements have shown that inelastic displacements can be more than 22% of the total displacement of the consoles by the time of the specimen failure. The effect of the Y2O3 stabilizer on the critical stress intensity factor KIc was verified. It was shown that an increase in the Y2O3 stabilizer content from 3 to 8% significantly decreases the fracture toughness. The stress intensity factor KIc falls within the range from 5.7 to 2.35 MPa m1/2. [ABSTRACT FROM AUTHOR]

An original method is proposed for the crack resistance determination of a material by wedge splitting of a chevron-notched specimen. It was developed at the Institute of Strength Physics and Materials Science SB RAS in the laboratory of Physical Mesomechanics and Nondestructive Methods of Control. An example of the crack resistance test of technical titanium VT1-0 is considered. [ABSTRACT FROM AUTHOR]

The aim of this paper is to study the flexural strength of concrete beam with Wulung Bamboo that has been in the notch as reinforcement. The notch is expected to increase the bonding effect and minimize the slip effects. This study used experimental laboratory method. Bamboo strip are processed and shaped with the notches of the v shape with the distance between the notches are 20, 30, 40, 50, 60 and 70 mm. The specimen size used in the form of a concrete beam is 110x150x1700 mm. Static loading is done with third point loading system (ASTM C78). The experimental results showed the performance of bamboo strips notch reinforced concrete beams increased compared to bamboo reinforcement without notch and the maximum load will increase as the number of notches increases. [ABSTRACT FROM AUTHOR]

Tool steels are considered as hard to deform materials since they have a mixture of soft ferritic matrix with hard carbides as secondary particles. In this study, 5 mm thick plates of AISI A8-Modified tool steel were subjected to cold rolling prior to the quench-temper cycle with the view to investigate the work hardening behavior of this steel during rolling and to reduce the brittleness of the product after the quench-temper cycle. 5mm thick samples were rolled 10, 20, 30, 40, and 50 (%) under similar conditions and then cut parallel to the rolling direction. Microstructure evolution, deformation-induced microvoids, and hardness evolution as a function of prior deformation were investigated. Electron microscopy was used to investigate the root causes for the formation of microvoids and potential alligatoring failure. The influence of microvoids on mechanical properties after the quench-temper cycle was evaluated through bending tests. Results showed no failure for 50% cold rolled sample in comparison with fracture for non-deformed sample indicating that prior deformation could be a novel route for improving the in service properties of these alloys. Hardness of 50% cold rolled after thermal hardening was lower than that for non-deformed sample. The analysis of prior austenite grain size, volume fraction of retained austenite, and volume fraction of carbides for both testing conditions showed that hardness reduction can be related to the presence of microvoids formed in the microstructure during rolling. [ABSTRACT FROM AUTHOR]

A hybrid glass/aluminum/titanium fiber metal laminate (FML) based on the standard GLARE concept was proposed in present paper, and its notched behavior was investigated experimentally and numerically. Experimental results revealed that a special three-stage stress-stain curve was obtained by this reinforced GLARE, which was related to the transition of load bearing mechanism. As well as, improvements of notched strength and normalized notched strength were achieved benefiting from the high strength and ductile nature of titanium, where their maximum increments obtained at D/W=0.2 were 11.88% and 15.40%, respectively. In addition, numerical results indicated that the finite element model (FEM) predicted well the notched behavior of GLARE with incorporating the thermal residual stress effect. Moreover, the comparisons of internal energy and damage dissipation energy between standard GLARE and reinforced GLARE have facilitated in the understanding of reinforced effect of titanium. It is believed that the present investigation can provide some useful information for damage tolerance design of FMLs. [ABSTRACT FROM AUTHOR]

A wavefront analysis indicates that a flexural wave propagates at a helix angle with respect to the pipe axis. The expression for calculation of the helix angle for each flexural mode is given, and the helix angle dispersion curves for flexural modes are calculated. According to the new understanding of flexural guided waves, a magnetostrictive helical array transducer (MHAT) is proposed for selectively exciting a single predominant flexural torsional guided wave in a pipe and inspecting spiral welded pipes using flexural waves. A MHAT contains a pre-magnetized magnetostrictive patch that is helically coupled with the outer surface of a pipe, and an array of novel compound comb coils that are wrapped around the helical magnetostrictive patch. The proposed wideband MHAT possesses the direction control ability. A verification experiment indicates that flexural torsional mode T(3,1) at center frequency f=64kHz is effectively actuated by a MHAT with 13-degree helix angle. A 20-degree MHAT is adopted to inspect a spiral welded pipe, an artificial notch with cross section loss CSL=2.7% is effectively detected by using flexural waves. [ABSTRACT FROM AUTHOR]

Guided ultrasonic waves are widely used for long range inspection. Higher Order Modes Cluster (HOMC), discovered at the author's research group [1-3] consist of multiple higher order guided wave modes that travel together as a single wave-packet and without appreciable dispersion for distances in the range of meters. These waves not only propagate along the length of the structure but also cover the entire thickness, and in view of the higher frequencies, they can offer improved resolution over conventional low-frequency guided waves. This paper studies the sensitivity of axial plate HOMC to notch-like defects, evaluated by calculating wave reflection co-efficient. The studies are carried out using finite element models validated by experiments. Analysis is presented for better understanding of wave-defect interaction. Advantages and limitations for practical realization of the above approach are also discussed. [ABSTRACT FROM AUTHOR]

Ultrasonic wavefield imaging, which refers to the measurement of wave motion on a 2-D rectilinear grid resulting from a fixed source, has been previously applied to angle-beam shear wave propagation in simple plates with through-holes and far-surface notches. In this prior work, scattered waves were analyzed using baseline subtraction of wavefields acquired before and after a notch was introduced. In practice, however, defects of interest often occur between bonded layers and it is generally not possible to record data from the same specimen in both the undamaged and damaged states, even in the laboratory. Direct baseline subtraction of wavefields thus becomes impractical as a tool for analyzing scattering. This present work considers measurement and analysis of angle-beam waves in bonded specimens with and without buried defects originating from fastener holes. Data from fastener holes with and without simulated damage in the form of notches are compared, and it is shown that wavefield baseline subtraction, even after correcting for misalignment between scans, is ineffective for isolating scattering from the notch. A combination of frequencywavenumber filtering and spatial windowing is proposed and implemented as an alternative approach to quantify scattering from damage. Despite unavoidable deviations from specimen-to-specimen caused by factors such as variations in bonding, transducer mounting, and fastener hole machining, it is shown that scattering from buried notches can be clearly visualized in recorded wavefield data of bonded plates containing a buried defect as opposed to "baseline" wavefield data taken from a nominally similar specimen with no defect present. Backscattering is further quantified in the form of scattering patterns at different scattering frames to quantify the effect of the notch on the total backscattered wavefield. [ABSTRACT FROM AUTHOR]

A model-based calibration process is introduced that estimates the state of the eddy current probe. First, a carefully designed surrogate model was built using VIC-3D® simulations covering the critical range of probe rotation angles, tilt in two directions, and probe offset (liftoff) for both transverse and longitudinal flaw orientations. Some approximations and numerical compromises in the model were made to represent tilt in two directions and reduce simulation time; however, this surrogate model was found to represent the key trends in the eddy current response for each of the four probe properties in experimental verification studies well. Next, this model was incorporated into an iterative inversion scheme during the calibration process, to estimate the probe state while also addressing the amplitude/phase fit and centering the calibration notch indication. Results are presented showing several examples of the blind estimation of tilt and rotation angle for known experimental cases with reasonable agreement. Once the probe state is estimated, the final step is to transform the base crack inversion surrogate model and apply it for crack characterization. Using this process, results are presented demonstrating improved crack inversion performance for extreme probe states. [ABSTRACT FROM AUTHOR]

Guided waves inspection is a well-established method for the long-range ultrasonic inspection of pipes. Guided waves, used in a pulse-echo arrangement, can inspect a large range of the pipe from a single point as the pipe structure carries the waves over a large distance due to the relatively low attenuation of the wave modes. However, the complexity of the dispersion characteristics of these pipe guided wave modes are well known, and can lead to difficulty interpreting the obtained results. The torsional family of guided wave modes are generally considered to have much simpler dispersion characteristics; especially the fundamental T(0,1) mode, which is nominally non-dispersive, making it particularly useful for guided wave inspection. Torsional waves have been generated by a circumferential ring of transducers to approximate an axi-symmetric load to excite this T(0,1) mode. Presented here is a new design of Electromagnetic Acoustic Transducer (EMAT) that can generate a T(0,1) as a single transducer, rather than a circumferential array of transducers that all need to be excited in order to generate an axisymmetric force. The EMAT consists of a periodic permanent magnet array and a single meander coil, meaning that the excitation of the torsional mode is greatly simplified. The design parameters of this new EMAT are explored, and the ability to detect notch defects on a pipe is demonstrated. [ABSTRACT FROM AUTHOR]

Guided ultrasonic waves are widely used for long range inspection. Higher Order Modes Cluster (HOMC), discovered at the author's research group [1-3] consist of multiple higher order guided wave modes that travel together as a single wave-packet and without appreciable dispersion for distances in the range of meters. These waves not only propagate along the length of the structure but also cover the entire thickness, and in view of the higher frequencies, they can offer improved resolution over conventional low-frequency guided waves. This paper studies the sensitivity of axial plate HOMC to notch-like defects, evaluated by calculating wave reflection co-efficient. The studies are carried out using finite element models validated by experiments. Analysis is presented for better understanding of wave-defect interaction. Advantages and limitations for practical realization of the above approach are also discussed. [ABSTRACT FROM AUTHOR]

In this paper, the fictitious radius - according to Neuber's method for determination of stresses at the notch root was used. Next, the fatigue lives of elements of the ring notches were calculated, and then compared with results of experimental tests of S235JR and 42CrMo4+QT steel samples. It has been demonstrated that the fictitious radius strongly depends on the expected fatigue life. [ABSTRACT FROM AUTHOR]

In the development of ship structures applying new materials and it's purposeful placement play an important role. During the last years, especially in a construction of ro-ro type vessels, the usage of novel sandwich structures in cargo decks is profitable. Steel sandwich panel is an innovative solution which at a todays state of development can be used for the construction of any members not taking part in a global bending of a hull. The one important reason for this is a lack of knowledge and experience in the fatigue assessment. The problem of fatigue assessment of the steel sandwich structures arises from no typical welds connecting its structural components. The joints are fabricated by the use of laser welding technique, or hybrid welding. Standard methodology for the fatigue analysis is local stress approach or local strain approach. In both methods the crucial aspect is determination of a maximum values of strains and stresses. The most effective technique to designate these values is numerical modelling with the use of Finite Element Method or Boundary Element Method. In this paper the comparison of local stresses at a weld notch obtained by two independent methods is presented. The results calculated by the Finite Element Analysis are being compared with the experimental one measured by the use of laser extensometer grid technique. The goal of this comparison is verification of the main numerical modelling assumptions. [ABSTRACT FROM AUTHOR]

This communication presents the results of the 2015 UT benchmark obtained with the models implemented in CIVA. The benchmark addresses the TOFD technique. To calculate the diffraction echoes, field by applying the pencilmodel and diffraction on notches edges is modelled by GTD (Geometrical Theory of Diffraction). We present comparisons between experimental and simulated results. We discuss the results obtained with and without applying the so-called "plane wave approximation" on the incident field. [ABSTRACT FROM AUTHOR]

A model-assisted POD (MAPOD) evaluation approach is explored for the eddy current inspection of fatigue cracks in titanium. Experimental results are presented comparing crack and EDM notch responses and different eddy current measurement systems. The MAPOD evaluation process is performed using a simulated case study, highlighting the benefit of leveraging better models to mitigate variation in the model fit and minimize test sample requirements. The benefit of validating NDE techniques that use inverse methods to estimate uncontrolled measurement conditions is also studied. [ABSTRACT FROM AUTHOR]

Non-linear ultrasonic parameter β and acoustic emission signals of ultrasonic fatigue testing were analyzed by using Laser Doppler Vibrometer and continuous AE waveform analysis system. Notched specimens of the high-strength low-alloy steel were prepared for the ultrasonic fatigue testing with exciting vibration frequency of 20 kHz. The AE events for each broken specimens were detected prior to the increase of β parameter. [ABSTRACT FROM AUTHOR]

This paper reports the development of ultrasonic phased array systems used for tubular inspection. First the design of a linear phased array is discussed with considerations of both theoretically and practically important factors. Then systems utilizing the linear phased array are introduced for different applications. To evaluate the system performance, tests were performed on flat bottom holes and artificial notches, including notches in longitudinal, transverse, and oblique orientations made according to API specifications. Test results have been presented. [ABSTRACT FROM AUTHOR]

Guided ultrasonic waves offer an efficient way for the long-term integrity monitoring of large structures. Permanently attached distributed or localized sensor arrays have been shown to be able to detect and localize simulated corrosion damage. Crack-like defects have a directivity pattern of the scattered field, which must be taken into account for the data processing algorithm. The directivity pattern of the scattered field for the A0 Lamb wave mode has been predicted from 3D Finite Element simulations and verified from experimental measurements at machined part-through and through-thickness notches. These results provide the basis for the quantification of the detection sensitivity for defects in plate structures using guided wave arrays. Using a hybrid model to account for the propagation distance and scattering characteristics, the relative amplitudes of received pulses for given sensor locations can be calculated. From a comparison with the signal to noise ratio of the array system, detection capabilities can be predicted for various defect sizes and orientation. [ABSTRACT FROM AUTHOR]

Optical surface inspection methods gain increasing importance since such inspection systems operate without contact and offer various possibilities for online defect detection and classification. In order to quantitatively evaluate different systems used for on-site inspections, we have performed an â versus a-analysis to determine the Probability of Detection (POD) for planar specimens with boreholes and notches of different dimensions and orientations. Following the international standard according to MIL-HDBK-1823 in the 2007 update version we have determined POD-curves using the digitized and algorithmically processed data. We show that the application of more complex sensor technology and algorithms correspondingly leads to improvement of the POD. [ABSTRACT FROM AUTHOR]

Results of detailed experimental measurements of the leaked magnetic field for two different steel plates with a machined notch presented in a companion paper are compared against the numerical predictions using commercial software COMSOL. The accuracy of the results is discussed in detail, as well as the ingredients that allow obtaining satisfactory computational results. Some interesting conclusions that derive from the numerical computations are also presented. For instance, the influence of the notch length on the amplitude of the recorded signal, the need to have a precise measurement of the magnetic permeability up to magnetic fields much higher than the magnetic field in the bulk of the material, etc. [ABSTRACT FROM AUTHOR]

The magnetic flux leaked by artificial notches machined by EDM is measured for two different rectangular steel plates. The measurements were performed for different field intensities, different liftoffs, and both sides, simultaneously recording the three components of the magnetic field. Attention was paid to the accurate measurement of the liftoff, and to make the magnetic history of the material as predictable as possible. This was achieved by measuring for decreasing magnetic excitations, starting from saturation. The descending branch of the major loop is measured and reported, to allow for a detailed comparison against numerical experiments. [ABSTRACT FROM AUTHOR]

This communication presents the results obtained on the configurations proposed in the 2010 UT modelling benchmark with the ultrasonic models implemented in the CIVA software. Experiments have been performed upon a planar block containing vertical planar backwall and surface breaking notches of different heights and extensions. The aim is to study the relative amplitudes of the notches echoes obtained after one bound on the backwall or after two bounds, on the backwall and then on the surface of the block. Side drilled holes and flat bottom holes were also present in the block for calibration. Two immersion probes of 5 MHz central frequency, for two different apertures, were used. The echoes are simulated by applying an integral formulation for the field radiated by the probe (the pencil-model) and a scattering model based on the Kirchhoff approximation. Comparison between simulated and experimental results are presented and discussed. [ABSTRACT FROM AUTHOR]

This paper presents results of an eddy current model validation study. Precise measurements were made using an impedance analyzer to investigate changes in impedance due to Electrical Discharge Machining (EDM) notches in aluminum plates. Each plate contained one EDM notch at an angle of 0, 10, 20, or 30 degrees from the normal of the plate surface. Measurements were made with the eddy current probe both scanning parallel and perpendicular to the notch length. The experimental response from the vertical and oblique notches will be reported and compared to results from different numerical simulation codes. [ABSTRACT FROM AUTHOR]

Considering the applications to in-line testing of products, water-free imaging technique is required. This study described defect imaging technique using a scanning laser source. Laser beam was emitted onto a surface of a plate, and then guided waves excited at the laser source were detected by ultrasonic transducers fixed on the plate surface. For a plate with rounded defects, amplitude distributions obtained by scanning the laser source corresponded to thickness distributions, but for plates with rectangular notches, unwanted artifacts were seen due to reflection, diffraction, and ultrasonic attenuation. Then, using multiple receiving transducers and synthesizing multiple images, distinct defect images were obtained for a flat plate and a curved plate with rectangular notches. [ABSTRACT FROM AUTHOR]

The notch effects on the high-cycle fatigue properties of Ti-6Al-4V ELI alloy have been investigated at cryogenic temperatures. Smooth and notched specimens with the Kt=1.5, Kt=2 and Kt=3 were prepared. High-cycle fatigue tests were carried out at 4, 77 and 293 K. One million cycles fatigue strength (FS) of smooth specimen was increased with a decrease of the test temperature. Although the FS of each notched specimen at 4 K were lower than those of 77 K. Fatigue crack initiation sites of the smooth, the Kt=1.5 and the Kt=2 notched specimens at 4 K were facets in the specimen interior (internal type fracture) and those of the Kt=3 notched specimens were at the notch root (surface type fracture). The size of individual facets comprising the internal fatigue crack initiation sites correspond to almost the α-grain size. Therefore, improvement of the fatigue strength of the notched specimens for Ti-6Al-4V ELI alloy which show internal type fracture at cryogenic temperatures requires attaining a smaller area size by grain refining. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

To evaluate material risk caused by human-error, the notch effects on the fatigue properties of forged Ti-5Al-2.5Sn ELI alloy have been investigated at cryogenic temperatures. Smooth and notched specimens with the Kt=1.5, 2 and 3 were prepared. High-cycle fatigue tests were carried out at 4, 77 and 293 K. The S-N curves of each specimen shifted to higher stress level with a decrease of the test temperature. At 4 K, the fatigue strength of the Kt=3 specimens were substantially lower than those of the smooth specimens. Although the notch effects on the fatigue properties of the Kt=1.5 and the Kt=2 notched specimens are not clear or significant. Fatigue crack initiation sites of the smooth and the Kt=1.5 notched specimens were in the specimen interior (internal type fracture) and those of the Kt=2 and the Kt=3 notched specimens were at the notch root (surface type fracture). The location of the fatigue crack initiation sites showed transition from the internal type fracture for the Kt=1.5 notched specimens to the surface type fracture for the Kt=2 notched specimens. Therefore, the Kt values of the internal fatigue crack initiation sites correspond between 1.5 and 2. The sizes of the internal fatigue crack initiation sites were calculated by the √area. The √area sizes of the Kt=1.5 notched specimens and the smooth specimens were in a similar range and the fatigue strength of the two are not significant. [ABSTRACT FROM AUTHOR]

Tensile tests of type 304L and 316L steels were carried out using round bar specimens with a notch in liquid helium, hydrogen, liquid nitrogen and at ambient temperature. The obtained tensile strengths were compared with the tensile strengths of smooth specimens. For smooth specimens, tensile strength increased with a decrease in temperature and the strengths in liquid helium and hydrogen show similar values in both steels. For notched specimen of 304L steel, tensile strength (including fracture strength) increased noticeably from ambient to liquid nitrogen temperature but showed a large decrease in liquid helium and hydrogen. In liquid hydrogen and helium, the tensile strength is a little lower in liquid hydrogen than in liquid helium and both strengths are lower than tensile strengths of smooth specimens. For notched specimen of 316L steel, an increase in tensile strength from ambient to liquid nitrogen temperature was not so large and a decrease from liquid nitrogen to liquid hydrogen was small. The tensile strengths in liquid helium and hydrogen were nearly same and higher than those of smooth specimens. Different behavior of serration was observed between liquid helium and hydrogen, and between 304L and 316L steels. The reasons for these differences were discussed using computer simulation. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Notch tensile behavior of alloy 718 is characterized in conventionally heat treated condition as a function of U and V notches at 25, 200 & 400 °C. The experimental results were then compared with the values obtained from simulation of notched geometries in ANSYS software using smooth specimen data. An excellent agreement is noticed between simulated and experimental true stress-true strain curves. [ABSTRACT FROM AUTHOR]