The Sky is Not Falling – Mechanical Damage Can Be Assessed Appropriately

Near wellbore damage has been a topic of great attention over last many decades. Typical measures of formation damage is skin factor (S) which is a hydrodynamic parameter characterizing additional resistance to flow of fluids in the near borehole zone of the reservoir, leading to reduced production (yield) compared to the perfect (ideal) wells. This has been a great attention of topic because it directly effects on formation fluid productivity from the concerning well. Reasons behind formation of this damage can be combinations of several mechanisms are clay particle swelling, fluid loss or change in formation water saturation, wettability reversal, Emulsion blockage, Mutual precipitation of soluble salts in wellbore-fluid filtrate and formation water, Deposition of paraffins or asphaltenes, Fines migration etc. Operations which are usually leads to those mechanisms to happen are drilling, cementing, well completion, work-over operations, production of fluids, injection of fluids and Operations to isolate water production etc. This paper describes mechanisms of the formation damage. And introduces types of skins depending on the mechanism of damage and source operation, and Types of skin are The mechanical or formation damage skin factors (Sd)Completion pseudo skin factor (Sp)Partial penetration skin factor (Spp)-Geometrical pseudo skin factor (Sg)Multiphase pseudo skin factor (Sm)Non-Darcy flow or Rate-dependent high velocity or turbulent flow pseudoskin factor (Sturb) This paper also describes all type of skin in detail with mathematical models given to calculate the skin individually as well as effective skin.

Assessment of the durability of elastomers for structural applications has been of much interest among the literary circles for quite some time. All polymeric materials undergo degradation when in contact with aggressive environmental agents like humidity, water, and temperature. This rate of degradation should increase with the growing intensity of the ambient environmental agents involved. On the other hand, during service life, these materials are also subjected to mechanical loading in one way or the other. The rate and extent of degradation can be accessed by scrutinizing the changes in constitutive behavior of material through mechanical and chemical properties. Accelerated thermal, hydrolytic, and hygrothermal aging are among the most common modes of process-related degradation, leading generally to chain scission, cross-linking phenomena, and reduced resistance to fracture stress and strain. In this experimental study, our goal is to separate the environmental degradation from mechanical damage. A polyurethane based (PUB) adhesive was aged in thermo-oxidative (0%RH), hydrolytic aging, and hygrothermal (80%RH) aging environments. The damage and decay mechanisms have been used to draw a distinction between environmental degradation and mechanical damage. Material characterization included cyclic tensile tests, gravimetric measurements to observe water-uptake, FTIR and scanning electron microscopy (SEM) tests on as-received and aged samples. Aging was conducted at three different temperatures (60°C, 80°C and 95°C) and four different exposure durations (1, 10, 30, and 90 days). This work confirms that environmental degradation is separable from mechanical damage. Data collected during gravimetric measurements indicate that during aging in desalinated water, water uptake increases linearly with the square root of the aging duration, which agrees with Fick’s second law. Increasing water uptake is proportional to decreasing tensile strength and toughness of the material. The total mechanical and environmental damage is a synergized effect of all exposure conditions and parameters involved i.e. aging time, temperature, oxygen, water, and humidity. The chemistry and mechanics of the polymer degradation were found to be in good agreement with each other.

ABSTRACT: Installation damage of geosynthetics occurs during their handling, positioning on the ground and the placing and compacting of fill material. Abrasion is a common damage mechanism where there is cyclic relative motion (friction) between a geosynthetic and contact soil. This paper presents the laboratory test results of mechanical damage and abrasion performed on six geosynthetics. The in isolation and combined effects on mechanical, hydraulic and physical properties of the geosynthetics were assessed. Results show that the effects of induced mechanical and abrasion damage essentially depend on the geosynthetic structure. For the most affected materials, strength losses after abrasion (in isolation and combined with mechanical damage) are higher than after the induced mechanical damage. Therefore, for most geosynthetics studied, abrasion is the conditioning mechanism which most affects their tensile strength. An increase of the characteristic opening size of the geosynthetics was observed, while their permittivity did not increase. This may be caused by differences in the test set-ups.

The theoretical and technological achievements in the damage mechanism and evaluation model obtained through the national basic research program “Key Fundamental Scientific Problems on Mechanical Equipment Remanufacturing” are reviewed in this work. Large centrifugal compressor impeller blanks were used as the study object. The materials of the blanks were FV520B and KMN. The mechanism and evaluation model of ultra-high cycle fatigue, erosion wear, and corrosion damage were studied via theoretical calculation, finite element simulation, and experimentation. For ultra-high cycle fatigue damage, the characteristics of ultra-high cycle fatigue of the impeller material were clarified, and prediction models of ultra-high cycle fatigue strength were established. A residual life evaluation technique based on the “β-HV-N” (where β was the nonlinear parameter, HV was the Vickers hardness, and N was the fatigue life) double criterion method was proposed. For erosion wear, the flow field of gas-solid two-phase flow inside the impeller was simulated, and the erosion wear law was clarified. Two models for erosion rate and erosion depth calculation were established. For corrosion damage, the electrochemical and stress corrosion behaviors of the impeller material and welded joints in H2S/CO2 environment were investigated. KISCC (critical stress intensity factor) and da/dt (crack growth rate, where a is the total crack length and t is time) varied with H2S concentration and temperature, and their variation laws were revealed. Through this research, the key scientific problems of the damage behavior and mechanism of remanufacturing objects in the multistrength field and cross-scale were solved. The findings provide theoretical and evaluation model support for the analysis and evaluation of large centrifugal compressor impellers before remanufacturing.

To ensure reliable core analysis results, in addition to the invasion-related core damage (discussed in Chap. 7), the least possible mechanical damage should occur to the core. Mechanical core damage is defined as a permanent change in rock properties which is not reversible by restoring the rock back to in situ conditions.

Soybean (Glycine max (L.) Merrill) seed susceptibility to mechanical damage during harvesting, threshing, and storage operations has decreased seed quality by reducing seed germination ability and seedling vigour, mainly in tropical and subtropical environments. This research aimed at estimating the genetic variability of seed response to mechanical damage (MD), and its relationship to agronomic characters such as plant height at maturity (PHM) and seed yield (SY). The material included 10 early maturity parents and 45 diallel crosses among them and five experimental checks. Ten F 8:5 experimental lines from each cross were evaluated. The statistical and genetical analyses included estimates of phenotypic and genotypic correlations; relative contribution of genetic effects versus combined genetic and environmental effects; relationship between the genetical and experimental variation coefficients; coefficient of genotypic determination; expected and observed gain; and, correlated response to selection. The parents Parana, Hale-321, IAC-Foscarin-31 and Primavera, showed the same MD resistance levels as IAS-5 cultivar, a standard check for MD resistance. The parents Palmetto, Coker-136, FT-81-1835 and Forrest were MD susceptible; however, they were superior to the IAC-2 cultivar, a standard check for MD susceptibility. The coefficient of genotypic determination for MD was estimated in 0.739, indicating large possibility to select MD resistant inbred lines in a population represented by the 45 diallel crosses. Expected and observed genetic gains indicated the possibility of success in the selection for resistance to MD among and within crosses. Based on the low genetic correlations (<0.25) among MD, PHM, and SY, all possible combinations of these traits could be found in a same soybean plant, at least in the early maturity group.

Radiation therapy is a widely used treatment for cancer, but it can have detrimental effects on the heart, leading to radiotherapy-induced cardiotoxicity. This condition has become an area of increasing concern, especially as cancer treatments continue to evolve. This review aims to explore the recent literature on radiotherapy-induced cardiotoxicity, focusing on the latest research published. The goal is to identify recent advances in understandings of the underlying mechanisms of damage, risk factors, screening modalities, risk stratification, and novel treatment strategies for mitigating radiotherapy-induced cardiotoxicity. A narrative literature review of PubMed articles from the last 3 years was conducted to gather recent research on radiotherapy-induced cardiotoxicity including keywords such as "cardiac complications," "cardiotoxicity," "radiotherapy," and "radiation." This review identifies advances in understanding the mechanisms of cardiac damage, particularly the roles of humoral immunity and endothelial dysfunction. Recent studies have also highlighted key risk factors, including radiation dose, genetic predispositions, underlying cardiovascular conditions, and lifestyle factors. Additionally, the review emphasizes the need for enhanced surveillance and early detection of cardiotoxicity following radiation therapy, proposing a combined approach involving both imaging techniques and biomarker monitoring for more accurate assessment. Novel imaging methods and emerging biomarkers are being explored for their potential in improving detection and risk stratification. This review article also outlines the national guidelines and clinical recommendations for the prevention and management of radiotherapy-related cardiotoxicity. Despite these advancements, there remain significant gaps in understanding the full range of factors contributing to radiotherapy-induced cardiotoxicity, including the genetic contribution and the interaction between radiotherapy and other cancer treatments with regard to their contributions to cardiotoxicity. Additionally, further research is indicated to further elucidate the mechanisms of damage and the significance of biomarker changes relating to cardiotoxicity. Overall, this review underscores the importance of ongoing research to mitigate the cardiovascular risks associated with radiotherapy.

It is known that the mechanisms of damage in the brain after stroke are regulated by combination of several types of cells, primarily of neurons, astrocytes, endothelium and microglia. Ischemic exposure disrupts the balance in the cellular composition of the brain; in the lesion, cells die by necrosis while in tissue surrounding ischemic zone the delayed induction of apoptosis occurs, and namely the ratio of death of different cells determines the clinical outcome of the disease. Thus, the assessment of death of various cell types of the neurovascular unit is an important part of fundamental studies of the mechanisms of brain damage and pre-clinical studies of potential neuroprotective drugs. In this line, we have conducted a comparative study of the two most often used methods: immunohistochemical staining of brain sections, allowing to determine the number and localization of specific cells in the tissue among other types of cells, and immunoblotting that detects specific proteins in the tissue homogenate. We have found that, depending on the type of cells, changes in their number and composition after stroke can be diffuse or localized, which imposes restrictions on the use of any method of estimation of the number of cells in brain tissue. In general, the most preferable is the use of immunohistochemistry, however, with certain limitations, immunoblotting can be used in estimating amounts of astroglia and microglia.

Investigation of localized damage in single crystals subjected to thermalmechanical fatigue (TMF)

&lt;div&gt; Damage Mechanisms Affecting Fixed Equipment in the Refining Industry &lt;/div&gt; &lt;div&gt; Recommended Practice 571 First Edition, December 2003 &lt;/div&gt;

The large majority of existing earth dams were designed with old standards, which often accounted for the effects of earthquakes in a simplified manner. As a result, seismic re‐evaluation of these structures is now becoming increasingly important for dam owners. The seismic performance of earth dams can be evaluated at different levels of resolution, typically ranging from simple sliding block analysis, to the use of advanced numerical models. Seismic inputs for these models are typically chosen using code‐based or site‐specific probabilistic seismic hazard analysis (PSHA). In this study, we analyze the seismic vulnerability of two major earth dams located in Southern Italy, a seismically active area. The two dam systems have different geotechnical characteristics: one of them is founded on potentially liquefiable materials, whereas the other one is not susceptible to liquefaction. Our analyses are based on finite difference numerical simulations using both simplified and advanced constitutive models. Seismic vulnerability of both dams is analyzed by means of analytical fragility functions for various damage mechanisms and ground motion intensity measures (IMs). Such fragility functions are based on nonlinear deformation analyses within the multiple stripe analysis framework. We analyze efficiency and predictability of various IMs in predicting different damage levels and mechanisms. We show that the cumulative absolute velocity is overall the optimal IM in predicting vulnerability of both earth dams. We also analyze the relative importance of PSHA inputs (i.e. alternative ground motion and earthquake rupture forecast models; GMMs and ERFMs, respectively) and numerical models (simplified vs advanced) in the seismic analysis of earth dams by means of tornado diagrams. We show that the choice of GMMs and ERFMs is always more important than that of the constitutive model. However, for dams prone to liquefaction, the choice of the constitutive model has a higher importance than for non‐liquefiable earth dams.

We investigate the damage characteristics and mechanism of neutral density filters consisting of metal film on K9 glass substrate by 1064-nm pulsed laser. The damage morphologies present marked differences with different laser pulse energies. Specifically, with the increase of laser fluence, the damage pits density increase as well, and at the same time, the cracks appear around the pits and interconnect, which lead to the abscission of film. The damage mechanism has been studied from the viewpoint of embedded impurities in the film. The theoretical results show that the difference between the thermodynamic properties of impurities and film can lead to thermos-elastic stress, which plays important roles in deformation of film, nucleation and propagation of cracks. Last, methods have been proposed to improve the laser damage resistance by controlling the size distribution of impurity particles and increasing the film tensile strength.

Hot corrosion influence on deformation and damage mechanisms in turbine blades made of IN-792 during service

Recently, research on the impact resistance of transparent hybrid glass-polymer systems (layered and particle-matrix systems) has been conducted at the Netherlands Organisation for Applied Scientific Research (TNO), showing the potential of these materials for the application in protection concepts. A soft, transparent polyurethane elastomeric polymer, Clear Flex 75 (CF 75 in short) was selected as matrix material. Knowledge about the impact resistance of particle(s)-polymer systems is also relevant for propellants, consisting of a polymer binder and solid energetic particles. The impact-induced damage will change the combustion properties and the performances of the propellant. Against this background, a combined research programme of experimental tests and computational modelling was defined on the mechanical response of hybrid particle(s)-polymer systems under dynamic loading. In this programme, CF 75 polymer is the matrix material, which is embedded with single and multiple particles. In the computational part, multi-scale modelling techniques for dynamic conditions are developed. In the experimental part, a step-wise approach with increasing complexity is conducted for studying the dynamic response in compression and tension of (i) a monolithic polymer matrix, (ii) a single-particle-polymer system and (iii) a multiple-particles-polymer system. The used apparatus is a small scale split Hopkinson bar (SHB) device developed at TU Delft, which can conduct the dynamic compression (SHPB) and tension (SHTB) tests at various strain rates. The experimental results are important for (i) the evaluation of a transparent impact-resistant device of a soft polymer material backed by rigid glasses, (ii) the development of a particle(s)-polymer system for propellants and (iii) the calibration of computational models for designing a rigid-particle-modified composite material system for protective applications. Firstly, the experimental setups were built for high-strain-rate tension (SHTB) and compression (SHPB) tests. These two setups were carefully evaluated and proved to be reliable for dynamic tests on a soft polymer material at different strain rate levels. The details on the technology for casting the specimens of the monolithic CF 75 polymer material, the single-glass-polymer system and the multiple-particles-polymer system were given, as well as the basic physical properties of CF 75 polymer material. Afterwards, the dynamic tension and compression experiments were conducted at various strain rate levels. During these tests, a high-speed camera was employed to record the dynamic loading process and a scanning electron microscopy (SEM) was used to carry out the post-test analysis. From the dynamic tension tests, the damage, fracture and toughness mechanisms of the monolithic CF 75 polymer material were revealed. The rate dependency of the mechanical properties and dynamic deformation behaviour were characterized. Then, the bonding of the glass-polymer interface was also characterized by dynamic tension loading on a single-glass-polymer system of the CF 75 polymer matrix with an embedded single 3mm-diameter glass particle. Debonding, cavitation and necking were illustrated, as well as the effects on the stress-strain response at various strain rates. Dynamic compression tests were carried out to characterize the impact-resistant performance of the monolithic CF 75 polymer material. They revealed the deformation behaviour, damage mechanisms, fracture characteristics, rate dependency of mechanical properties and temperature rise. Then, the single-glass-polymer system was tested by dynamic compression tests. The results clarify the particle effect on the dynamic compressive response. The debonding-induced decrease of yield stress and the contribution of glass particle failure to fracture energy are quantitatively characterized at various strain rates. Finally, the impact-resistant performance of the multiple-particles-polymer systems of CF 75 polymer matrix with embedded 25wt.% and 50wt.% 0.5mm-diameter PMMA particles was characterized by dynamic compression tests. For the multiple-particles-polymer systems, an improved static stiffness is explained. Multiple cracking from the particle-polymer interface is observed, which induces the decrease of yield stress. A high particle density results in the decrease of maximum stress and strain energy. However, crushing of the particles causes a faster increase of maximum stress and strain energy with increasing strain rate (indicated by a higher strain rate sensitivity index). In this thesis, a systematical investigation about the dynamic mechanical response of soft polymers was carried out. It includes the monolithic polymer material (as matrix material in the particle(s)-polymer system), the single-glass-polymer system (for studying the interfacial bonding and single particle effect), and the multiple-particles-polymer system (as a representative of the real particle(s)-polymer system for impact-resistant applications).

Tribological behavior of Ti–6Al–4V alloy: Subsurface structure, damage mechanism and mechanical properties