http://yetl.yabesh.ir/yetl1/handle/yetl/4255483 2026-08-25T05:39:14Z 2026-08-25T05:39:14Z Rahman, Waliur Shougat, Md Raf E Ul Peters, Kara http://yetl.yabesh.ir/yetl1/handle/yetl/4315994 2026-08-23T08:02:30Z 2026-01-01T00:00:00Z

Shear-Horizontal Wave Manipulation Using Flexural Resonance-Based Elastic Metamaterial Rahman, Waliur; Shougat, Md Raf E Ul; Peters, Kara Abstract. Shear-horizontal (SH) waves offer unique advantages for guided wave-based structural health monitoring applications. Their in-plane motion reduces sensitivity to environmental conditions. Additionally, the non-dispersive SH0 mode minimizes signal distortion. This article employs resonant metamaterials to focus SH0 waves before detection by a sensor. The objective is to amplify the signal and overcome attenuation of the mode as it propagates through a structure. The results show that flexural resonances of the unit cell modify SH modes and produce polariton-like dispersion behaviors. The dispersion curve for the SH mode through the metamaterial exhibits three distinct regions: non-dispersive, dispersive, and polariton. These regions are then used to design a frequency-selective metamaterial system for SH0 waves in a plate. The results represent the first demonstration of focusing SH0 modes using resonant metamaterials.

2026-01-01T00:00:00Z Ha, Yoosung Negyesi, Martin Hasegawa, Kunio Lacroix, Valery http://yetl.yabesh.ir/yetl1/handle/yetl/4315993 2026-08-23T08:02:28Z 2026-01-01T00:00:00Z

Applicability of Instrumented Indentation for Assessing Allowable Flaw Sizes of Circumferentially Flawed Stainless Steel Piping Ha, Yoosung; Negyesi, Martin; Hasegawa, Kunio; Lacroix, Valery Abstract. Structural integrity assessment of flawed pipes, as required by ASME B&PV Code Section XI, relies on failure stress calculated by the limit load criterion (LLC). The failure stress is derived from flow stress, which depends on yield and ultimate tensile strengths. Instrumented indentation technique (IIT) is a nondestructive alternative to conventional tensile testing. A large number of studies related to IIT reported that IIT is capable of assessing the yield strength and the ultimate tensile strength with 10% accuracy compared to the tensile testing. The benefit of IIT for the analysis of allowable flaw sizes is critically assessed in this study based on experimental data and code calculations. Intrinsic standard deviations of yield and ultimate tensile strengths for type 304 stainless steels are discussed in this article. As a result, the IIT method is capable of estimating the flow stress for type 304 stainless steel within 3.2% deviation from the result of conventional tensile tests. Then, the allowable circumferential flaw sizes for pipes subjected to tensile loading are calculated based on strength properties assessed by IIT. In addition, the allowable flaw sizes are compared to the allowable flaw sizes derived from the flow stress tabulated in the ASME B&PV Code Section II, Materials. The conclusion is drawn that IIT yields a sufficiently accurate estimate of the flow stress on austenitic stainless steel piping. Therefore, IIT is a beneficial method for LLC.

2026-01-01T00:00:00Z Cao, Dongdong Hao, Jianan Xun, Zhi http://yetl.yabesh.ir/yetl1/handle/yetl/4315992 2026-08-23T08:02:26Z 2026-01-01T00:00:00Z

Local Defect Detection of Cable Impedance Spectrum by Using Fast Inverse Fourier Transform Cao, Dongdong; Hao, Jianan; Xun, Zhi Abstract. Cables are a key component of power systems. Local defects such as insulation aging and mechanical damage can easily cause serious faults. Impedance spectroscopy analysis has become a research hotspot in defect detection due to its noninvasive nature and sensitivity. However, traditional Fourier transforms have problems such as weak noise suppression, low characteristic resolution, spectral leakage, and insufficient low-frequency resolution, which limit the ability to detect minor defects. To address this limitation and achieve high-precision detection and location of local defects in cables, this article adopts an improved method based on the inverse fast Fourier transform (IFFT). The equivalent time component (2l/v) is extracted from the reflection coefficient spectrum at the beginning of the cable, and the time–frequency resolution is optimized by combining the adaptive window function. The defect characteristic frequency band is enhanced through the frequency-domain weighting algorithm, and the location function DF(x) is constructed to highlight the defect differences. Meanwhile, the signal propagation speed is simulated and measured by comsol software to provide key positioning parameters. Experiments show that this method is not sensitive to the strength of the injected signal (as long as the minimum power is met), but sensitive to the severity of defects. It can accurately locate multiposition defects (such as defects at 10 m, 20 m, and 40 m on a 60 m XLPE cable) and is not affected by cable curls. It is suitable for high-voltage cables and radio frequency (RF) cables with semiconductive layers.

2026-01-01T00:00:00Z Wall, James J. Hohmann, Brian P. http://yetl.yabesh.ir/yetl1/handle/yetl/4315991 2026-08-23T08:02:25Z 2026-01-01T00:00:00Z

Feasibility of Monitoring Flaws in Nuclear Reactor Primary Loop Piping Systems Using Surface Strain Measurements—Phase 2: Pressurized Welded Pipe Mock Ups Wall, James J.; Hohmann, Brian P. Abstract. The material presented in this article summarizes the results from phase 2 of a larger Electric Power Research Institute (EPRI) study to determine if permanently mounted strain sensors can be used to monitor and quantify the presence and growth characteristics of flaw indications in primary loop piping in light water nuclear power reactors (LWRs). The samples utilized in this phase 2 work consisted of butt welded sections of austenitic 304 stainless steel pipe segments. Axial and circumferential notches, intended to simulate service flaws of varying depths and lengths, were generated into the inner diameter (ID) of the samples. Resistive strain gauges were applied in longitudinal (axial) and transverse (hoop) orientations, on the outer diameter (OD) in the vicinity of the notch locations. The axial notches perpendicularly intersected the weld while circumferential notches were generated along the weld fusion planes on one side (15 deg from the radial direction). The notch morphologies, strain gauge placement details, and a summary of the strains measured during pressurization tests are presented in this article. Based on the strain data obtained, transverse strain measurements may be sufficient to allow online monitoring (OLM) of axial and circumferential flaws in the vicinity of welds in the LWR pressurized primary coolant loop austenitic stainless steel piping and components.

2026-01-01T00:00:00Z