Effect Of Surface Damage Research Articles

The Analysis of Liquefaction Potential and Post-Liquefaction Deformations at a Highway Bridge Crossing

The primary goal of this study is to geotechnically analyze the soil strength and liquefaction potential of the soil where the Seyrek highway junction and the bridge are built under earthquake-related dynamic stress. The analyses include comparisons of liquefaction potential using various empirical approaches, studies of post-liquefaction vertical deformation, and investigations into the influence of fill soil on liquefaction-induced surface deformation. Since the analyses of liquefaction potential in soils are made based on the "Simplified Method" approach, this method was also used in this study. This study also used the "Simplified Method" approach, which is the basis for studies of soil liquefaction potential. Four standard penetration tests (SPT) on the bridge piers were used to collect field data, and experiments in the lab were used to establish the requisite soil parameters. When the results of the Simplified Method analysis were performed according to the soil properties of the SK-1, SK-2, SK-3, and SK-4 drillings and the liquefaction analysis results were determined according to the required safety factor (Fs), liquefaction potential up to 18.5 meters was determined in all four SPT locations. Moreover, the results of surface damage effect analyses of the non-liquefied cover/fill layer on the Seyrek crossing bridge soil for all four SPP fields were found to be 'visible" and the liquefiable layer thickness (H2) was found to be 10.5 m. The calculated liquefaction severity index (LS) value was found to be up to 52, which means the liquefaction effect was found to be 'Possible liquefaction damage'.

Durability and damage model of polyacrylonitrile fiber reinforced concrete under freeze–thaw and erosion

In an alpine saline soil area, the combined effect of freeze–thaw and erosion ions causes the imbalance of concrete durability. In studying the macro–meso deterioration law and failure mechanism of polyacrylonitrile fiber-reinforced concrete (PANFC) under this action, PANFC specimens formed by open-air curing were prepared, and a composite salt solution containing 5% MgSO4, 5% Na2SO4, and 3.5% NaCl was used as the freeze–thaw medium for salt-freezing test. Results demonstrate that the degradation of PANFC under salt-frost conditions can be divided into the micro-damage stage and damage acceleration stage, with 50 cycles as the limit. When the content of PAN fiber is 1.5–1.8 kg/m3, the salt frost resistance of concrete is advantageous. The macro-scale results show that the relative dynamic elastic modulus and ultrasonic wave velocity of PANFC decrease with the increase of salt-freezing cycles, whereas the weight of PANFC increases before 25 salt-freezing cycles. The meso-scale results show that after 50 cycles, the evolution of micro-pores to macro-pores and micro-cracks in PANFC is accelerated. The pore size ratio of micro-pores (0–0.1 μm) decreases with the increase of cycles, and the pore size ratio of micro-cracks (greater than10 μm) increases with the increase of cycles. Failure mechanism analysis shows that the failure of PANFC results from the combined effect of surface damage and internal damage. Finally, the salt-frost damage model of PANFC was established on the basis of the damage mechanics and classical Aas-Jakobsen fatigue theory, and the damage determination value Dn was between 0.2527 and 0.2781. Using Dn, the failure criteria of concrete damaged under salt-frost conditions can be re-evaluated.

Effects of cavitation erosion-induced surface damage on the corrosion behaviour of TA31 Ti alloy

This study used electrochemical noise technology to analyse the effects of surface damage induced by cavitation erosion (CE) on the pitting and passivation behaviours of TA31 Ti alloy. According to the results, TA31 Ti alloy exhibited high corrosion resistance in NaCl solutions. However, the residual tensile stress layer generated during grinding and polishing reduced its passivation ability. Subsequently, the residual tensile stress layer was eliminated after CE for 1 h, improving the passivation ability of the material. Thereafter, pitting corrosion was initiated on the material surface. Increasing the CE time from 1 h to 2 h gradually decreased the passivation ability of the alloy. A large number of CE holes promoted the transition from pitting initiation to metastable pitting growth. which gradually dominated the surface of TA31 Ti alloy. The damage mechanism of uniform thinning increased the passivation ability and stability of the alloy with the increase in CE time from 2 h to 6 h. Therefore, the surface of TA31 Ti alloy was dominated by the initiation of pitting corrosion.

A novel index combining temperature and vegetation conditions for monitoring surface mining disturbance using Landsat time series

The exploitation and utilization of mineral resources have significantly contributed to economic and social development; however, the procession has also negatively impacted the ecological environment. Thus, it is necessary to effectively monitor coalfields, an important basis for reasonable development and utilization of coalfields and following ecological reclamation. Based on MODIS Global Damage Index, We couple the Land Surface Temperature (LST) and Normalized Difference Vegetation Index (NDVI), and proposal the Mine Landscape Damage Index (MLDI) and Mine Landscape Reclamation Index (MLRI) to supervise the disturbed vegetation of mines. Huolinhe coalfield, one of the largest mines in China, is monitored in this research. 3675 Landsat imageries from 1990 to 2020 are analyzed using the LandTrendr algorithm with MLDI and MLRI time series data on Google Earth Engine. The results demonstrate that this method could distinguish the region and disturbing process of damage and reclamation due to its effectiveness proved by visual interpretation of high-resolution imageries and verification of field investigation. The total detected area of vegetation damage was 16505.10 ha, and the vegetation damage in the mining was active from 2006 to 2011, with average annual damage of more than 1000 ha. The total area of vegetation restoration in the mine is 8640.81 ha, accounting for 52.35% of the vegetation damage. Vegetation restoration has increased gradually since 2010. In the past three years, vegetation restoration accounted for 47.61% of the total reclamation area. A novel index for monitoring the effects of surface damage in multi-open-pit mining areas is provided to us, and the detection is reliable. It can give the government an effective practical data reference in the sustainable development of utilization management and ecological reclamation in coalfield.

Effect of surface damage induced by cavitation erosion on pitting and passive behaviors of 304L stainless steel

Effect of surface damage induced by cavitation erosion on pitting and passive behaviors of 304L stainless steel

Analysis of interstrip capacitance of p+n MCz Si microstrip detector using TCAD simulation combining surface and bulk damage effects by mixed irradiation

Interstrip capacitance plays a crucial role on the detector electronic noise performance at the readout electrode of the irradiated detectors in the harsh radiation environment of the high luminosity Large Hadron Collider experiments. The major challenge is to optimize the design of the detector to get the low interstrip capacitance in the real ‘mixed’ irradiation environment of the experiment. A few of experimental studies have been performed within CERN RDD0 collaboration on the n-MCz Si detectors to extract the microscopic parameters for the surface and bulk damage effects especially by mixed irradiations in the detectors. The results on the microscopic parameters are fed into ATLAS TCAD commercial simulation program to compare the experimental data and simulation result. A very good agreement has been recorded between the data and simulation result. In this paper, the microscopic model parameters are used to investigate the effects of mixed irradiation up to a fluence of 8.82× 1014 neq./cm2 on the interstrip capacitance in n-MCz 〈100〉 silicon microstrip detectors. The results are discussed in detail using electric field distribution, electron concentration profile in the irradiated detectors for the different metal overhang width, and an optimized p+n-MCz Si microstrip design is proposed for the future collider experiment.

Development and test of innovative Low-Gain Avalanche Diodes for particle tracking in 4 dimensions

The MIUR PRIN 4DInSiDe collaboration aims at developing the next generation of 4D (i.e., position and time) silicon detectors based on Low-Gain Avalanche Diodes (LGAD) that guarantee to operate efficiently in the future high-energy physics experiments. To this purpose, different areas of research have been identified, involving the development, design, fabrication and test of radiation-hard devices. This research has been enabled thanks to ad-hoc advanced TCAD modelling of LGAD devices, accounting for both technological issues as well as physical aspects, e.g. different avalanche generation models and combined surface and bulk radiation damage effects modelling. In this contribution, it is reviewed the progress and the relevant detector developments obtained during the research activities in the framework of the 4DInSiDe project. • TCAD modelling for the design of radiation-hard LGAD sensors for 4D tracking. • Gain layer compensation, (p ＋ - and n ＋ -doping) to preserve the gain at high fluences. • New design approach to resistive read-out sensors: DC-coupled RSD. • DC-RSD employs a direct coupling of the resistive layer to the read-out pads. • DC-coupled low resistivity strips between read-out pads to improve the resolution.

Analysis of Bulk and Surface Radiation Damage in n+ in p SFz Si Micro Strip Detectors for the Future High Luminosity Collider Experiments: TCAD Simulation and Measurements

Within the framework of CERN RD50 collaboration, several radiation damage models for n/p-SFz, n-MCz Si have been explored for the better understanding of the experimental results in radiation damage analysis of the irradiated Si detectors. In the present paper, the important review on the microscopic radiation damage model for the p-type SFz Si detector combining the surface and radiation damage effects that can be used to simulate radiation damages effects in the heavily irradiated detectors for the good comparison of the experimental data and simulation result. The surface radiation damage models were extracted from the experimental measurements on the p-MOS capacitor and Gate-Controlled Diodes irradiated by Gamma or X-ray radiations in the range of 10 to 500 Mrad (Si). Whereas, the bulk damage model microscopic parameter was extracted from the experimental (TSC, DLTS) measurements on the n in p-SFz Si microstrip detector. The radiation damage (surface and bulk) models can be fed into the commercial Synopsys TCAD device simulator program for the designing and optimization of the detector, which can be used in the very harsh radiation environment of the HL-LHC, or FCC experiment. The objective of this analysis was to verify the experimental results using the new microscopic radiation damage models on the p-SFz Si for the radiation damage analysis of p- SFz Si detectors irradiated by proton, neutron or mixed at very high fluences. The results were verified by comparison of the experimental data with TCAD simulation.

Time-Dependent Sensitivity of Structural Reliability Assessment to Multi-Source Uncertainties Using Lamb Wave

Abstract This article investigates the time-dependent sensitivity of structural reliability assessment to multisource uncertainties using Lamb wave. To precisely model the influence of local damage on the structure in the course of damage growth, a surface damage effect model is proposed to obtain the equivalent elasticity modulus, which can be coupled with the structure model. The evolution of the surface damage is modeled using the fatigue crack propagation model. Furthermore, by setting up the component and structure failure criteria, the time-dependent reliability model of the structure under multisource uncertainties from Lamb wave detection and material properties is established. The method of score function is employed to evaluate the sensitivity index, which is defined as the derivative of the reliability with respect to the distribution parameters of uncertain variables. A spatial truss structure is used to demonstrate the overall procedure. Numerical results show that the sensitivities indices are time and damage size dependent. The sensitivity contributions from Lamb wave quantification model and the material properties are comparable when the crack size is relatively small. When the crack grows to a larger size, the reliability assessment result is much more sensitive to uncertainties associated with material properties.

TCAD modeling of bulk radiation damage effects in silicon devices with the Perugia radiation damage model

The “Perugia Surface and Bulk” radiation damage model is a Synopsys Sentaurus Technology CAD (TCAD) numerical model which accounts for surface and bulk damage effects induced by radiation on silicon particle detectors. In this work, the significance of the input parameters of the model, such as electron/hole cross sections and acceptor/donor introduction rates is investigated, with respect to the changes in leakage current, full depletion voltage, charge collection efficiency and the current-related damage factor α (an irradiated device’s figure of merit) of a PIN diode. Different types (IV, 1/C2-V) of comparisons are made between simulation outputs and experimental data taken from irradiated PIN diodes. Finally, the possibility of the analytical model’s validation with the examination of the Low-Gain Avalanche Detector (LGAD) case, and its general application for future silicon sensors is discussed.

TCAD simulations of non-irradiated and irradiated low-gain avalanche diodes and comparison with measurements

In this work, the results of Technology-CAD (TCAD) device-level simulations of non-irradiated and irradiated Low-Gain Avalanche Diode (LGAD) detectors and their validation against experimental data will be presented. Thanks to the intrinsic multiplication of the charge within these silicon sensors, it is possible to improve the signal to noise ratio thus limiting its drastic reduction with fluence, as it happens instead for standard silicon detectors. Therefore, special attention has been devoted to the choice of the avalanche model, which allows the simulation findings to better fit with experimental data. Moreover, a radiation damage model (called “New University of Perugia TCAD model”) has been fully implemented within the simulation environment, to have a predictive insight into the electrical behavior and the charge collection properties of the LGAD detectors, up to the highest particle fluences expected in the future High Energy Physics (HEP) experiments. This numerical model allows to consider the comprehensive bulk and surface damage effects induced by radiation on silicon sensors. By coupling the “New University of Perugia TCAD model” with an analytical model that describes the mechanism of acceptor removal in the multiplication layer, it has been possible to reproduce experimental data with high accuracy, demonstrating the reliability of the simulation framework.

Fatigue strength assessment of high-speed railway axle EA4T steel with foreign object damage

Axle is easy to be hit by ballast and other foreign object rolled up due to aerodynamic effect to form the typical foreign object damage (FOD) on the surface, leading to deteriorate the axle structural integrity and reduction of fatigue performance. In order to evaluate the effects of surface damage and strengthening treatment on the fatigue performance, the EA4T axle steel specimens with or without shot peening (SP) were induced FOD by a compressed-gas gun. Meanwhile, the strengthening mechanism of shot peening were investigated by both nanoindentation technique and X-ray diffraction. Then the probabilistic fatigue S-N curves (P-S-N) were acquired for unSPed and SPed specimens subjected to FOD or not. In addition, the fatigue limit of FODed axle estimated by Murakami equation was corrected by size effect, surface quality, loading mode factors. Finally, the fatigue limits with 97.5% reliability were adopted to construct the modified Kitagawa-Takahashi (K-T) diagrams for FODed axle with or without shot peening treatment, which can be used in the service performance evaluation of foreign object damaged axle.

Dominant factors and their action mechanisms on material removal rate in electrochemical mechanical polishing of 4H-SiC (0001) surface

Slurryless electrochemical mechanical polishing (ECMP) has been confirmed as a highly efficient damage-free polishing technique for SiC wafers. To increase the material removal rate of ECMP, it is essential to have a better understanding of the anodic oxidation mechanism of SiC to obtain a much higher anodic oxidation rate. In this study, we investigated the effects of electrolyte temperature, surface damage, doping concentration, and strain on the anodic oxidation rate of SiC. All these factors were found have a promotional effect on the anodic oxidation of SiC. The promotional effects of processing-induced damage and doping on SiC anodic oxidation were attributed to the processing-induced residual strain and doping-induced strain on the SiC surface, which were observed by Raman spectroscopy. The relationship between anodic oxidation rate and strain on the SiC surface was quantitatively investigated by applying a strain-controllable anodic oxidation device. Both compressive and tensile strains were found to increase the anodic oxidation rate of SiC. The promotion mechanism of the strain on the anodic oxidation of SiC was studied by conductive atomic force microscopy observations. This study is expected to be an important guide for improving the efficiency of ECMP and will contribute to the practical application of ECMP.

Geometrical model for calculating the effect of surface morphology on total x-ray output of medical x-ray tubes.

PurposeCorrelation of characteristic surface appearance and surface roughness with measured air kerma (kinetic energy released in air) reduction of tungsten‐rhenium (WRe) stationary anode surfaces.MethodsA stationary anode test system was developed and used to alter nine initially ground sample surfaces through thermal cycling at high temperatures. A geometrical model based on high resolution surface data was implemented to correlate the measured reduction of the air kerma rate with the changing surface appearance of the samples. In addition to the nine thermally cycled samples, three samples received synthetic surface structuring to prove the applicability of the model to nonconventional surface alterations. Representative surface data and surface roughness values were acquired by laser scanning confocal microscopy.ResultsAfter thermal cycling in the stationary anode test system, the samples showed surface features comparable to rotating anodes after long‐time operation. The established model enables the appearance of characteristic surface features like crack networks, pitting, and local melting to be linked to the local x‐ray output at 100 kV tube voltage ,10° anode take off angle and 2 mm of added Al filtration. The results from the conducted air kerma measurements were compared to the predicted total x‐ray output reduction from the geometrical model and show, on average, less than 10 % error within the 12 tested samples. In certain boundaries, the calculated surface roughness Ra showed a linear correlation with the measured air kerma reduction when samples were having comparable damaging characteristics and similar operation parameters. The orientation of the surface features had a strong impact on the measured air kerma rate which was shown by testing synthetically structured surfaces.ConclusionsThe geometrical model used herein considers and describes the effect of individual surface features on the x‐ray output. In close boundaries arithmetic surface roughness Ra was found to be a useful characteristic value on estimating the effect of surface damage on total x‐ray output.

TCAD Modeling of Surface Radiation Damage Effects: A State-Of-The-Art Review

A comprehensive numerical model which accounts for surface damage effects induced by radiation on silicon particle detectors is presented with reference to the state-of-the-art Synopsys Sentaurus Technology CAD (TCAD) tool. The overall aim of this work is to present the “Perugia 2019 Surface” damage modeling scheme, fully implemented within the TCAD environment, which effectively describes the surface damage effects induced by radiation in silicon sensors relying on a limited number of parameters relevant for physics. To this end, extensive measurement campaigns have been recently performed on gated-diodes and MOS capacitors at Fondazione Bruno Kessler (FBK) in Italy, Hamamatsu Photonics (HPK) in Japan and Infineon Technologies (IFX) in Austria on both n-type and p-type substrates (with and without p-spray isolation implants), in order to extrapolate the relevant parameters which rule the surface damage effects. The integrated interface trap density and the oxide charge density, have been determined before and after X-ray irradiation with doses ranging from 0.05 to 100 Mrad(SiO2), for each specific foundry and technology flavor. The main guidelines of this study are the versatility and generality of the simulation approach.

Surface Damage and Bleaching Effect according to the Application Type of Home Tooth Bleaching Applicants

Surface Damage and Bleaching Effect according to the Application Type of Home Tooth Bleaching Applicants

Effects of surface damage on critical current density in MgB2 thin films

We investigated the influence of surface damage on the critical current density (Jc) of MgB2 thin films via 140-keV Co-ion irradiation. The Jc(H) of the surface-damaged MgB2 films was remarkably improved in comparison with that of pristine films. The strong enhancement of Jc(H) caused by a surface damage in MgB2 films can be ascribed to additional point defects along with an atomic lattice displacement introduced through low-energy Co-ion irradiation, which is consistent with the change in the pinning mechanism, from weak collective pinning to strong plastic pinning. The irreversible magnetic field (Hirr) at 5 K for surface-damaged MgB2 films with a thickness of 850 and 1300 nm was increased by a factor of approximately 2 compared with that of a pristine film. These results show that the surface damage produced by low energy ion irradiation can serve as an effective pinning source to improve Jc(H) in a MgB2 superconductor.

Measurements of surface and bulk radiation damage effects in silicon detectors for Phase-2 CMS Outer Tracker

In this work we address the effects of bulk and surface damages on detectors fabricated by Hamamatsu on standard float zone (FZ) p-type material with an active thickness of 290 µm or thinned to 240 µm. In order to disentangle the effects of the two main radiation damage mechanisms, ionization effects and atomic displacement, the structures underwent two types of radiation: X-ray with doses from 0.05 to 70 Mrad (SiO2) and neutron in the range of 1−10 × 1014 neq/cm21MeV equivalent. The combined surface and bulk damage could be investigated in structures that underwent both types of irradiation. A wide set of measurements has been carried out on the test structures for a complete characterization.

Microstructure and tribological property of selective laser melted Ni-based composites using different scanning strategies

The effect of laser scanning strategy on microstructure and tribological property of WC/Inconel 718 composites manufactured by selective laser melting (SLM) was investigated. The microstructure of composites demonstrated columnar dendrites with <001> texture while the precipitates distribution and dendrites spacing were distinct by virtue of heat flux rotation. The island strategy with nearly full density possessed high microhardness (366.2 HV0.2) and low wear rate (1.72 × 10−4 mm3/N⋅m), showing the superior wear resistance. The wear rate of cross-direction displayed little difference with island owing to their similar structures. While the remelting strategy demonstrated spherical pores and aggregated precipitates owing to the excessive heat-input, which was more easily subjected to wear and mechanism transformed from abrasive wear to severe plastic deformation and adhesion. Besides, the wear resistance was weakened and wear debris transformed to flakes with the increase of applied load because of the effect of surface damage and loss.

Machining for an increased fatigue life for a Ti-6Al-4V ELI component

Abstract Fatigue life is an important design criterion for many structural parts. The surface integrity induced by a typical machining operation may have a marked effect on fatigue life. Literature evidence suggests that the compressive surface residual stress state may change appreciably from the state obtained at the recommended conventional cutting speeds when intermediate cutting speeds are utilized. Titanium alloys typically show an increased compressive residual stress state at intermediate speeds before eventually tending towards tensile stresses at elevated cutting speeds. This paper investigates the effect of an optimised cutting strategy to control the residual stress state of a machined Ti-6Al-4V ELI (extra low interstitial) component to thereby control the fatigue life. An experimental program is conducted whereby stepped shafts are machined at various cutting speeds before being subjected to a full cyclic in-plane bending moment fatigue test. Cutting speed is varied between the typically recommended speed of 40 m/min to an intermediate speed of 110 m/min. Residual stresses are measured by XRD and compared to the fatigue life achieved. Other surface integrity descriptors including surface roughness, sub surface microstructure and selected surface damage effects are presented and discussed in relation to the fatigue performance. In essence the paper reports that fatigue life can be improved by machining at the optimum cutting speeds. These optimum intermediate speeds do however introduce other less desirable effects such as an increase in surface damage including the presence of weldments and ploughing grooves that may have a negative effect on the reliability of the improvements obtained.