Structural Integrity Evaluation Research Articles

Neural Selective Cryoneurolysis with Ice Slurry Injection in a Rat Model.

Postoperative pain caused by trauma to nerves and tissue around the surgical site is a major problem. Perioperative steps to reduce postoperative pain include local anesthetics and opioids, the latter of which are addictive and have contributed to the opioid epidemic. Cryoneurolysis is a nonopioid and long-lasting treatment for reducing postoperative pain. However, current methods of cryoneurolysis are invasive, technically demanding, and are not tissue-selective. This project aims to determine whether ice slurry can be used as a novel, injectable, drug-free, and tissue-selective method of cryoneurolysis and resulting analgesia. The authors developed an injectable and selective method of cryoneurolysis using biocompatible ice slurry, using rat sciatic nerve to investigate the effect of slurry injection on the structure and function of the nerve. Sixty-two naïve, male Sprague-Dawley rats were used in this study. Advanced Coherent anti-Stokes Raman Scattering microscopy, light, and fluorescent microscopy imaging were used at baseline and at various time points after treatment for evaluation and quantification of myelin sheath and axon structural integrity. Validated motor and sensory testing were used for evaluating the sciatic nerve function in response to ice slurry treatment. Ice slurry injection can selectively target the rat sciatic nerve. Being injectable, it can infiltrate around the nerve. The authors demonstrate that a single injection is safe and selective for reversibly disrupting the myelin sheaths and axon density, with complete structural recovery by day 112. This leads to decreased nocifensive function for up to 60 days, with complete recovery by day 112. There was up to median [interquartile range]: 68% [60 to 94%] reduction in mechanical pain response after treatment. Ice slurry injection selectively targets the rat sciatic nerve, causing no damage to surrounding tissue. Injection of ice slurry around the rat sciatic nerve induced decreased nociceptive response from the baseline through neural selective cryoneurolysis.

On the concept of micro-fracture map (MFM) and its role in structural integrity evaluations in materials science and engineering: A Tribute to Jorge Manrique

This paper deals with the concept of micro-fracture map (MFM) and its role in structural integrity evaluations in materials science and engineering, on the basis of previous research by the author on notch-induced fracture and hydrogen embrittlement of progressively cold drawn pearlitic steels and 316L austenitic stainless steel. With regard to this, some examples are provided of assembly of MFMs in particular situations.

Development of In-Service Inspection Rules for Liquid-Metal Cooled Reactors Using the System Based Code Concept

Abstract Inservice inspection rules for liquid-metal cooled plants were historically provided by Section XI, Division 3 of the ASME Boiler and Pressure Vessel Code. However, some parts of the Code, such as acceptance standards for the examination of class 1 and 2 components remained as being in the course of preparation. Although no major revisions were made to Division 3 since the first issue in 1980, a newly developed and published Code Case N-875 now provides alternative examinations to the methods previously contained in Division 3. The Code Case was developed using the System Based Code (SBC) concept pursuing rationalization of codes and standards based on reliability targets throughout a plant's service life. In this paper, an overview of the Code Case is presented. The technical foundation to establish the applicability of these alternative examinations as delineated in the Code Case consists of stage I and II evaluations with compensating individual considerations. Stage I is a structural integrity evaluation without the contribution of inservice inspections, while stage II is evaluation of the detectability of a postulated flaw. Not only conventional direct detection methods, but also indirect detection methods are permitted to be employed through the stage II evaluation. Furthermore, the detailed evaluation procedures are illustrated through the application of the Code Case's evaluation criteria to the primary heat transport piping system of a prototype sodium-cooled fast breeder reactor in Japan, specifically Monju.

Structural integrity evaluation of CNG pressure vessel with defects caused by heat treatment using numerical analysis

Natural gas vehicles use natural gas as a raw material; thus, compared to conventional diesel vehicles, there is no soot or fine dust produced, the noise generated is half, and the amount of air pollution is one tenth. Despite a considerable increase in their demand, there is still much controversy in terms of their safety, and safety-related accidents have frequently occurred in recent years. According to reports, most compressed natural gas (CNG) bus accidents are caused by the rupture of the pressure vessel, and the reason for this accident is that the containers show a high number of manufacturing defects. In the case of a metallic liner, the mechanical properties and rupture characteristics of the pressure vessel vary greatly depending on the method and conditions of the heat treatment process. Several accidents where pressure vessels have ruptured have been reported, and all these ruptures occurred owing to brittle fracture of the container because the mechanical properties, such as the tensile strength and the fatigue strength of the CNG vessel changed in comparison with the normal vessel owing to poor heat treatment processes. In this study, we compared and analyzed the structural integrity and fatigue characteristics of the normal vessel and the poorly heat-treated vessel under charging conditions and under an atmospheric environment, where the vessel is mounted on an actual CNG bus. This comparison is made through a heat convection and conduction analysis using SINDA/FLUENT and a structure and fatigue analysis using ADINA and winLIFE.

Evaluation of the environmental aging of the glass fiber-reinforced polymer composite when in contact with the effluent of a treatment plant

This paper presents an evaluation of the mechanical and physical behavior of the type E glass fiber-reinforced polymeric composite when exposed to environmental aging agents in an effluent treatment plant. The composite was made by the hand layup process, and the test bodies were made according to the American Society for Testing and Materials standards D3039-14 and D790-10 for the uniaxial tensile and three-point bending tests, respectively, where they were exposed for a period of eight months, conditioned above and immersed in the effluent of the treatment plant. The physicochemical characterization of the effluent was evaluated considering the following parameters: pH, conductivity, sulfate, alkalinity, acidity, sulfide, and temperature, aiming to characterize the effluent conditions in direct and indirect contact with the composite. After the exposure period, tests were carried out for morphological evaluation, structural integrity evaluation, mechanical performance evaluation, and fracture characterization of the polymer composite, thereby leading to a comparison of the mechanical characteristics in the original state to that of the aged state (after exposure in the effluent treatment plant). The polymeric composite studied was stable after the aging period, with little mass variation, less than 0.5%, and slight changes in color. The mechanical properties evaluated also did not change significantly during the study period. Variations in uniaxial tensile strength were less than 1.4% and for three-point bending less than 10%, thus showing that the type E glass fiber-reinforced polymer composite has potential for use in harsh environments such as in effluent treatment plants.

Large thermal gradients on structural integrity of a reactor pressure vessel subjected to pressurized thermal shocks

Pressurized-thermal-shocks (PTSs) are the most severe accidents that impact the structural integrity of a pressurized water reactor pressure vessel (RPV). In general, the one-dimensional thermal-hydraulic analysis results for PTS transients were often used as the loading conditions for structural integrity evaluation of RPV, but may cause over-conservative results. This paper investigates the effects of the cold plume, which is the non-uniform temperature distribution caused by colder water injected separately into the RPV, on the fracture probability of a three loop pressurized water reactor (PWR) vessel subjected to PTS events. The three-dimensional computational fluid dynamics (CFD) technique associated with probabilistic fracture mechanics (PFM) analysis were employed to comprehensively evaluate the structural integrity of RPV under hypothetical PTS accidents. Firstly the model of a PWR pressure vessel in Taiwan was constructed to simulate the thermal-hydraulic phenomena by CFD methodology. Based on the Best Practice Guidelines (BPGs) and ASME V&V guidance, the estimation of mesh uncertainty has been conducted. Then the detailed thermal-hydraulic boundary conditions corresponding to various RPV shell regions were regarded as the loading conditions for PFM analysis. Present results are compared with those which consider the simplified thermal hydraulic analysis system code's results as boundary conditions.

Nondestructive Spot Weld Quality Evaluation by Measurement of Structural Vibration Transfer Through Joined Panels

A nondestructive test method using structural vibrations was proposed for spot weld quality evaluations. The wave propagations in multi-spot-welded structures were analyzed using the spectral element method. The resonance frequency showed dependence on the spot stiffness due to the out-of-phase vibration modes locally generated at the testing spot. The experiments to measure the local vibrations were performed. A vehicle specimen made of multi-spot-welded ultra-high-strength steel panels was used for the evaluation. After exciting one side of the spot by an electric shaker, the resulting vibrations were measured on the other side. The transmitted responses by the input vibrations at the testing spot were obtained. The resonance frequencies depended on the wavelength for local vibrations in the specimen. The weld stiffness was predicted using the vibration transfer function. The estimated weld quality was compared to the actual spot diameter. The weld quality had influence on the dynamic properties and resonant modal vibration of the part under tests. To minimize the effect of the geometric and boundary conditions, the local vibrations affected only by the weld quality was used in this study. The proposed method enabled the efficient structural integrity evaluation using the vibration measurements of the welded structure.

Queensferry Crossing, UK: durability, maintenance, inspection and monitoring

The new Queensferry Crossing in Scotland, UK, is a durable structure designed to minimise degradation and withstand the challenging environment of the Forth estuary. High-performance materials, rigorous compliance testing and advanced protective measures have been employed to this end. An effective, integrated monitoring, inspection and maintenance system was developed to facilitate early intervention and maintain the bridge in a sustainable condition. A range of access facilities, including motorised gantries, shuttle trains and mechanical lifts have been provided to ensure safe and effective access, within touching distance, to all internal and external surfaces. An advanced structural health monitoring system has been installed to monitor the condition and integrity of the bridge, allowing rapid evaluation of structural integrity after extreme events and the identification of changes in condition over time.

Evaluation of Structural and Functional Integrity of the Rotator Cuff After Total Shoulder Arthroplasty

Evaluation of Structural and Functional Integrity of the Rotator Cuff After Total Shoulder Arthroplasty

함정용 Sliding Type 수밀문의 구조안정성 평가

함정용 Sliding Type 수밀문의 구조안정성 평가

The functional role of beta-oscillations in the supplementary motor area during reaching and grasping after stroke: A question of structural damage to the corticospinal tract.

Hand motor function is often severely affected in stroke patients. Non-satisfying recovery limits reintegration into normal daily life. Understanding stroke-related network changes and identifying common principles that might underlie recovered motor function is a prerequisite for the development of interventional therapies to support recovery. Here, we combine the evaluation of functional activity (multichannel electroencephalography) and structural integrity (diffusion tensor imaging) in order to explain the degree of residual motor function in chronic stroke patients. By recording neural activity during a reaching and grasping task that mimics activities of daily living, the study focuses on deficit-related neural activation patterns. The study showed that the functional role of movement-related beta desynchronization in the supplementary motor area (SMA) for residual hand motor function in stroke patients depends on the microstructural integrity of the corticospinal tract (CST). In particular, in patients with damaged CST, stronger task-related activity in the SMA was associated with worse residual motor function. Neither CST damage nor functional brain activity alone sufficiently explained residual hand motor function. The findings suggest a central role of the SMA in the motor network during reaching and grasping in stroke patients, the degree of functional relevance of the SMA is depending on CST integrity.

Creep damage characterization of UNS N10003 alloy based on a numerical simulation using the Norton creep law and Kachanov–Rabotnov creep damage model

The calculation of inelastic creep damage is important for the structural integrity evaluation of the elevated temperature structure in a thorium molten salt reactor (TMSR). However, a creep damage theory model and numerical simulation method have not been proposed for the key materials (UNS N10003 alloy) in the TMSR. In this study, creep damage characterization of UNS N10003 alloy is investigated using the Norton creep law and Kachanov–Rabotnov (K–R) creep damage model. First, the creep experimental data of the UNS N10003 alloy at 650 °C were adopted to fit the material constants of the two models. Then, the creep damage behavior of the UNS N10003 alloy was analyzed and discussed under uniaxial and multi-axial stress states. The results indicated that the K–R creep damage model is more suitable for the UNS N10003 alloy than the Norton model. Finally, the numerical simulation method was developed by a user-defined UMAT subroutine and subsequently verified through a finite element analysis (FEA). The FEA results were in agreement with the theoretical solutions. This study provides an effective method for the inelastic creep damage analysis of the elevated temperature structure in the TMSR.

Evaluation of structural integrity and functionality of commercial pectin based edible films incorporated with corn flour, beetroot, orange peel, muesli and rice flour

The present study aims to develop functional composite edible films using varied film formulations containing pectin (P), corn flour (CF), beetroot powder (BP), orange peel powder + sodium alginate (OPS), muesli root powder (MRP) and rice flour (RF) along with their structural, mechanical and functional characterization. Strong intermolecular attachment evolved between starch and pectin molecules due to hydrogen bonding of their hydrophilic groups, confirmed through scanning electron micrographs and FTIR spectra. Also, P-CF ratio (1:1) might retained some crystalline regions of starch which has significantly enhanced structural integrity and functionality of films in terms of tensile strength (TS), water solubility (WS), water vapour permeability (WVP) and thermal stability. In accordance with Herschel-Bulkley model, the predicted consistency index and flow behaviour values were affected by film formulation and the model was of good fit with R2 = 0.81 (PC3), R2 = 0.74 (PCB3) and R2 = 0.99 (for rest formulations). Although, higher proportions of hydrophilic polymers (P, OPS & BP) due to higher molecular mobility resulted in less rigid, highly soluble, moisture permeable and thermally unstable films. Furthermore, RF films possessed cracks over the surface and insoluble fractions due to insufficient starch gelatinization which decreased their TS and barrier properties. The ATR-FTIR spectra confirmed the presence of functional groups corresponding to starch and pectin in range of 500–4000 cm−1. The variation among different films underlies only in peak intensities due to some molecular changes. Overall, the films made of P-CF ratio (1:1) were more functional and structurally stable as compared to rest of the films, thus, they would make a better alternative for synthetic packaging.

Structural Integrity Assessment of a Propellant tank in Presence of Welding Residual Stresses

Upper stage of India’s new generation launch vehicle makes use of cryogenic propellants with liquid hydrogen (LH2) and liquid oxygen (LOX) as fuel and oxidizer respectively. The propellants are stored in tanks fabricated of Aluminum alloy and contain various openings. As carrying out proof test at operating environment is not feasible, the tanks are subjected to proof pressure test at room temperature (RT). During the RT proof pressure test of LOX tank, high strains, greater than 8000με, were recorded by gauges at three locations where weld rework had been undertaken. From structural analysis, the maximum welding residual stress at these locations is evaluated to be 95N/mm2. From stress analysis point of view, positive margins were observed with respect to failure of the tank even in presence of these residual stresses.However, since the tank is operating at cryogenic temperature, though there is an increase in the yield and ultimate strengths of the tank material, there is a reduction in ductility (lower percentage elongation). Therefore, evaluation of structural integrity of the hardware from fracture point of view is of paramount importance. A study was undertaken to investigate the influence of residual stresses on integrity of the tank in presence of minimum detectable crack sizes using conventional NDE techniques. The location where maximum strains were observed, post proof test, is considered for fracture evaluation. Directional stresses at location of interest are predicted through detailed finite element analysis. Subsequently, generalized Failure Assessment Diagram was drawn based on Elasto-Plastic fracture mechanics principles and margin against ultimate load ensured. The tank was used in a launch vehicle which was successfully flown in June 2017.

Evaluation of structural integrity of tactical missile ceramic radomes under combined thermal and structural loads

Radome is a thermo-structural member used in tactical missiles and houses the avionic systems like seeker. It is subjected to severe thermal as well as structural loads during the flight. The material of the radome is chosen such that it is transparent electromagnetic radiation. The ceramic radome is attached to the metallic bulkhead with high temperature glue. In the present manuscript, the experimental evaluation methodology implemented for evaluation of the structural integrity of the ceramic radome under combined thermal and structural loads is presented. Initially axial load, to simulate the resultant drag force and a distributed lateral load, to simulate the bending moment, are applied via a pre-casted contoured Teflon mock sections, up to proof load and then time varying temperature is applied. The time-varying temperature profile is applied via a closed loop control based on PID and the heating environment is created using short wave infra-red radiation. Exhaustive instrumentation is used in the experiments. Detailed results are also presented in the manuscript up to the structural failure.

Using seismoacoustic sounding technique for the purpose of structural integrity evaluation of the solid reinforced-concrete foundation for the power transmission line supports

During construction of the monolithic reinforced-concrete foundation, it is not easy to monitor both a continuous haulage and technology of concrete placement. For that matter, some breach of the foundation structural integrity may occur. Currently, there is no unanimous integrated practice of monitoring concrete placement for building oversize solid reinforced-concrete foundations. The surveying results of the solid concrete foundation dimensioned 16m by 16m and from 2 to 3.5m thick are set forth in the article. Such geophysical technique as seismoacoustic sounding has proved effective for concrete placement quality control of monolithic reinforced-concrete foundations by means of a non-destructive method.

Computation of the stress intensity factor KI for external longitudinal semi-elliptic cracks in the pipelines by FEM and XFEM methods

Evaluation of structural integrity of a cracked structure has become an important matter in the industrial field since couples of decades. However, damage process occurred in a structural component is not yet fixed. The objective of this research was to compute the stress intensity factor KI, in mode I, using in the linear elastic domain, by the finite element method and the extended finite element method. The defect studied in this survey has a form of a longitudinal semi-elliptic crack, located on the outer surface of the tube. A summary of the paper contains a numerical convergence for each method in terms of accuracy and limitations. The proposed methodology and outcomes released from this study act as novel design tool for the industrial engineers when is required to generate a robust solution for product development working in critical conditions.

Structural Integrity Evaluation of Large MOD Restorations Fabricated With a Bulk-Fill and a CAD/CAM Resin Composite Material.

To evaluate the effect of two composite restorative techniques (direct bulk fill vs indirect CAD/CAM) on the fracture resistance and mode of fracture of extended mesio-occlusal-distal (MOD) cavity preparations. Fifty-one sound human mandibular third molars were divided into three groups (n=17). Extended bucco-lingual MOD cavities were prepared. Teeth in group 1 were restored with a bulk-fill resin composite (Filtek Bulk-Fill Posterior Restorative), teeth in group 2 were restored with composite computer-aided design/computer-aided manufacturing (CAD/CAM) inlays (Lava Ultimate), and teeth in group 3 served as control and remained intact. All specimens were submitted to thermocycling, and a fracture resistance test was performed using a Universal testing machine (0.5 mm/min). Mode of fracture was classified into five types. One-way analysis of variance and the Duncan test were used to analyze the fracture load data at a significance level of α = 0.05. A chi-square test was used for the analysis of fracture mode between the restorative groups. Statistical analysis showed significant differences in fracture resistance among the experimental groups. The teeth restored with the bulk-fill composite exhibited lower fracture resistance (1285.3±655.0 N) when compared to the teeth restored with the composite CAD/CAM inlays (1869.8±529.4 N) (p<0.05). Mode of fracture showed the same distribution between the restorative groups. Although both types of restorations failed at loads larger than those found in the oral cavity, the CAD/CAM composite inlays increased the fracture resistance of teeth with large MOD cavities when compared to direct bulk-fill composite restorations. The majority of fracture types were intraorally repairable for both restorative techniques.

Pedestrian: Probabilistic fracture mechanics analysis code based on direct sampling with replacement

Probabilistic fracture mechanics (PFM) is a rational methodology in structural integrity evaluation for nuclear power plants, and several PFM analysis codes have been developed. In general, the statistical distributions of random variables such as initial crack sizes and material properties are expressed as probability density functions, and a set of random variables are sampled from those functions for each repeated failure analysis to obtain the cumulative failure probability. Since most random variables are considered to have physical upper and lower limits in their distribution, it is essential to set reasonable cut-offs in the functions to avoid improper samplings. If a sufficient quantity of measured data is available, their population is supposed to intrinsically include the information from such limits. In this study, we developed a PFM analysis code, that can sample the variables based on the direct sampling of measured data by sampling with replacement in order to rationally evaluate the failure probability. The difference in failure probability was discussed between the general sampling procedure, which uses probability density functions, and the direct sampling procedure. Consequently, the failure probability obtained by the direct sampling procedure was approximately an order of magnitude lower than that obtained by the general sampling procedure.

Evaluation of Structural Integrity of the ISO-based Moon Pool Type Diver Boats

Evaluation of Structural Integrity of the ISO-based Moon Pool Type Diver Boats