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This paper sets out to propose a wafer prealigner based on multi‐sensor integration and an effective prealignment method implemented on it.

The wafer and notch eccentricities, on which wafer prealignment is based, are calculated with the peripheral data of the wafer detected by a laser displacement sensor and a transmission laser sensor by means of barycenter acquiring algorithm in a one‐particle system.

The center and notch prealignment precisions of the system are, respectively, ±1.5 μm and ±30 μrad. Experimentation has proved the validity and effectiveness of the system.

The wafer prealigner is a subsystem of the lithography in the semiconductor industry. The prealignment algorithm can be implemented in any object with random figures.

The periphery of the wafer is detected by a high‐precision laser displacement sensor and a low‐cost transmission laser sensor instead of a CCD linear sensor used by traditional wafer prealigners, which saves the space occupation of the structure and enhances the systematic prealignment precision. Using barycenter acquiring algorithm in a one‐particle system to calculate the wafer and notch eccentricities is effective and valid.

The purpose of this paper is to estimate the number of cycles for fatigue crack initiation in notched plates.

Previously published experimental results for tests with initially uncracked U‐shaped notches of different sizes and geometries are utilized. The present work defines the fatigue initiation period, N_i, as number of loading cycles required for the formation of a through‐thickness Mode I crack at the notch root macroscopically propagating along the plate width. Thus, backward extrapolation of the observed early decreasing fatigue growth rates of the initiated crack at the notch root on the specimen surface to zero surface crack size enables the estimation of N_i.

A parameter based on the normal strain range and the maximum normal stress acting at the notch root best fitted N_i.

This paper provides an estimation of N_i in 3 mm thick mild steel plates subjected to constant amplitude uniaxial cyclic stresses. Initiated‐but‐non‐propagating cracks possibly found at the notch surface and at the notch root along the plate width are distinguished.

Based on the present analysis, a threshold stress is devised to represent the minimum stress level required for the appearance of a through‐thickness crack at the notch root running along the specimen width. Notched plates simulate many engineering applications particularly in aerospace industry.

This study investigates the fitting techniques for notch fatigue curves, seeking a more reliable method to predict the lifespan of welded structures.

Building on the fatigue test results of butt and cruciform joints, this research delves into the selection of fitting methods for the notch fatigue curve of welded joints. Both empirical formula and finite element methods (FEMs) were employed to assess the notch stress concentration factor at the toe and root of the two types of welded joints. Considering the mean stress correction and weld misalignment coefficients, the notch fatigue life curves were established using both direct and indirect methods.

An engineering example was employed to discern the differences between the direct and indirect approaches. The findings highlight the enhanced reliability of the indirect method for fitting the fatigue life curve.

While the notch stress approach is extensively adopted due to its accurate prediction of component fatigue life, most scholars have overlooked the importance of its curve fitting methods. Existing literature scantily addresses the establishment of these curves. This paper offers a focused examination of fatigue curve fitting techniques, delivering valuable perspectives on method selection.

The stress state near the notch affects fatigue damage directly, but quantifying the stress field is difficult. The purpose of this study is to provide a mathematical description method of the stress field near the notch to achieve a reliable assessment of the fatigue life of notched specimens.

Firstly, the stress distribution of notched specimens of different materials and shapes under different stress levels is investigated, and a method for calculating the stress gradient impact factor is presented. Then, the newly defined stress gradient impact factor is used to describe the stress field near the notch, and an expression for the stress at any point along a specified path is developed. Furthermore, by combining the mathematical expressions for the stress field near the notch, a multiaxial fatigue life prediction model for notched shaft specimens is established based on the damage mechanics theory and closed solution method.

The stress gradient factor for notched specimens with higher stress concentration factors (V60-notch, V90-notch) varies to a certain extent when the external load and material change, but for notched specimens with relatively lower stress concentration factors (C-notch, U-notch, stepped shaft), the stress gradient factor hardly varies with the change in load and material, indicating that the shape of the notch has a greater influence on the stress gradient. It is also found that the effect of size on the stress gradient factor is not obvious for notched specimens with different shapes, there is an obvious positive correlation between the normal stress gradient factor and the normal stress concentration factor compared with the relationship between the shear stress gradient factor and the stress concentration factor. Moreover, the predicted results of the proposed model are in better agreement with the experimental results of five kinds of materials compared with the FS model, the SWT model, and the Manson–Coffin equation.

In this paper, a new stress gradient factor is defined based on the stress distribution of a smooth specimen. Then, a mathematical description of the stress field near the notch is provided, which contains the nominal stress, notch size, and stress concentration factor which is calculated by the finite element method (FEM). In addition, a multiaxial fatigue life prediction model for shaft specimens with different notch shapes is established with the newly established expressions based on the theory of damage mechanics and the closed solution method.

This paper aims to study and modify the notch equivalent stress method, as well as to establish the notch equivalent stress range S–N curve and apply it to the fatigue assessment of engineering examples.

This paper studies the notch equivalent stress method and puts forward the concept of “singular equivalent crack”. Combined with the fatigue test results, by proposing to consider the singular coefficient of the transition angle of the welded structure and the introduction of material correction factors, this paper derives the notch equivalent stress equation for commonly used welded joints applicable to steel, and finally establishes the notch equivalent stress range of the S–N curve.

The obtained results show that the dispersion of fatigue data is 65.6 and 75.4% for T-joints and transverse cross-joints, respectively, under S–N curves using notched equivalent stress compared to the nominal stress range. The fatigue evaluation error of the modified notch equivalent stress equation for transverse cross welded joints improved by 50.65%, 53.1 and 39.6% on average, respectively, compared to the original other methods. The fatigue evaluation error for T-joints improved by 13.4 and 13.9%, respectively, compared to the original other methods.

There are relatively few studies on the fatigue assessment of notch equivalent stress method. In this paper, the notch equivalent stress method is studied and modified to improve the accuracy of fatigue assessment of welded structures with singular stresses.

It is well known that notches have a deleterious influence on the fatigue strength of parts. A constant, the sensitivity index, is commonly used to relate the fatigue stress concentration factor to the elastic stress concentration factor. The author outlines a simpler hypothesis, which he claims to be a more reliable guide to fatigue behaviour in notches. Briefly it assumes that the elastic stress concentration factor gives the reduction in the fatigue strength due to the notch, but because of the local nature of the stress concentration, the endurance limit is increased according to a simple law. This increase in the fatigue strength depends on the smallness of the notch.

The purpose of this paper is to introduce a numerical investigation used to calculate the J-integral of the main crack behavior emanating from a semicircular notch and double semicircular notch and its interaction with another crack which may occur in various positions in (TiB/Ti) functionally graded material (FGM) plate subjected to tensile mechanical load.

For this purpose the variations of the material properties are applied at the integration points and at the nodes by implementing a subroutine USDFLD in the ABAQUS software. The variation of the J-integral according to the position, the length and the angle of rotation of cracks is demonstrated. The variation of the J-integral according to the position, the length and the angle of rotation of cracks is examined; also the effect of different parameters for double notch FGM plate is investigated as well as the effect of band of FGM within the ceramic plate to reduce J-integral.

According to the numerical analysis, all parameters above played an important role in determining the J-integral.

The present study consists in investigating the simulation used to calculate the J-integral of the main crack behavior emanating from a semicircular notch and double semicircular notch and its interaction with another crack which may occur in various positions in (TiB/Ti) FGM plate under Mode I. The J-integral is determined for various load applied. The cracked plate is joined by bonding an FGM layer to TiB plate on its double side. The determination of the gain on J-integral by using FGM layer is highlighted. The calculation of J-integral of FGM’s involves the direction of the radius of the notch in order to reduce the J-integral.

This paper aims to present the design of a novel triangular-shaped wideband microstrip bandpass filter implemented on a low-cost substrate with a notched band for interference rejection.

The conventional dual-stub filter is embedded with simple fractal-based triangular-circular geometries through various iterations to reject wireless local area network (WLAN) signals with a notched band at 5.8 GHz.

The filter covers a wide frequency band from 3.1 to 8.8 GHz and has a fractional bandwidth of 98 per cent with the lower passband of 57.5 per cent and upper passband of 31.6 per cent separated by a notched band at 5.8 GHz. The proposed wideband prototype bandpass filter is fabricated in FR-4 substrate using PCB technology and the simulation results are validated with measurement results which include insertion loss, return loss and group delay. The fabricated filter has a sharp rejection of 28.3 dB at 5.8 GHz. Measured results show good agreement with simulated responses. The performance of the fractal-based wideband filter is compared with other wideband bandpass filters.

In the proposed work, a fractal-based wideband bandpass filter with a notched band is reported. The conventional dual-stub filter is deployed with triangular-circular geometry to design a wideband filter with a notched band to suppress interference signals at WLAN frequency. The proposed wideband filter exhibits smaller size and better interference rejection compared to other wideband bandpass filter designs implemented on low-cost substrate reported in the literature. The aforementioned wideband filter finds application in wideband wireless communication systems.

The purpose of this paper is to present and validate a methodology for the structural integrity assessment of components containing a variety of stress risers and subjected to static conditions.

The methodology is based on the use of the apparent fracture toughness prediction provided by the theory of critical distances (in this case, the line method), together with a well‐known, widely‐used engineering tool in structural integrity assessments: failure assessment diagrams. In order to validate the proposed methodology, an experimental programme has been conducted, testing 38 specimens made of aluminium alloy Al7075‐T651, each of them containing a certain stress riser. The comparison between the experimental results and the corresponding predictions provided by the proposed assessment methodology has also allowed the situations for which the theory of critical distances provides accurate predictions to be defined.

The results show that the methodology provides accurate results as long as the Neuber number, defined as the notch radius divided by the critical distance (L), is sufficiently low. In order to extend the validity to situations where the Neuber number is higher, it is necessary to calibrate L by using notched specimens with similar radii to those found in the defects being analysed.

The present study is part of Virginia Madrazo's doctoral thesis, an original research work.

The purpose of this paper is to retrieve the dielectric constant of the material under test (MUT) by using an empirical relationship, which relates the dielectric properties with all three resonant frequencies of the proposed sensor. Each notch of the sensor is analyzed for sensitivity by using 15 different MUTs with relative permittivity ranging from 1.006 to 16.5 with a fixed dimension of 12 mm × 12 mm × 1.2 mm.

In this paper, we present a triple-notch metamaterial-based sensor for the solid dielectric characterization based on a microstrip transmission line and a direct coupled-double split ring resonator (DC-DSRR). The proposed sensor is designed, and its response is measured using a vector network analyzer to verify the concept. The shift in the resonant frequencies of the proposed sensor owing to contact with MUT is depicted as a function of permittivity using the curve fitting tool.

The proposed sensors have three notches, with the third notch being more sensitive than the first and second notch because of the high resonance frequency. For the first, second and third resonances, the proposed sensor has sensitivity ranges from 4.9% to 14.68%, 8.97% to 23.95% and 15.48% to 29.36%, respectively. The findings of the simulations, measurements and formulations are all in good accord.

In comparison to previous solid dielectric metamaterial sensors, the proposed triple-notch sensor based on a microstrip transmission line and DC-DSRR has the following advantages: it has a simple unit-cell structure and meets the needs of miniaturization, compact size, low cost and improved sensitivity. It determines the relative permittivity using all three notches so that the accuracy of the measurement is enhanced as compared with single- and double-notch sensors.