Effect Of Local Damage Research Articles

Investigation on the Effect of Energy Release Rate of Aluminized Explosive on the Damage of Underwater Targets

AbstractAs a type of high‐energy explosive, aluminized explosives are extensively used in underwater weapons and ammunition. This study aims to investigate the energy release rate on the damage of underwater targets caused by aluminized explosives (RDX/Al). The ship was selected as a target, and numerical simulations were conducted using AUTODYN software to study the energy release rate corresponding to different particle sizes of aluminum powder (25 nm −300 μm) in the underwater explosion process of RDX/Al, as well as its destructive effect on targets in the water. The research quantitatively evaluates the whole ship′s destruction results, including longitudinal bending deformations and crevasse. In addition, typical cabins were selected in this study to assess the local damage effects by analyzing stress, shock wave pressure, displacement, and acceleration shock response. Based on the damage results, it was revealed that RDX/Al with aluminum powder particle sizes ranging from 54 nm to 145 nm exhibited the most optimal damaging effects on ships after underwater explosions. These findings provide a basis for improving the destructive power of aluminized explosives against underwater targets, simultaneously, they can be utilized by ship designers to guide research and development of improved protective measures, aiming to reduce the vulnerability of ships to explosive attacks.

Assessment and Non-Bandaging Treatment of Third-degree Thermal Injury in the Dog: A Case Report

Dogs– scalds are a significant concern in veterinary practice. The causes can vary with common sources including hot water, boiling liquids, heated surfaces, and household accidents. Factors such as age, breed, and environment may influence the likelihood of scald injuries in dogs. Human negligence can contribute to the occurrence of scald injuries therefore pet owners should be educated about potential hazards in the household to ensure a safe environment and provide proper supervision and significantly reduce the risk of scald injuries. Thermal burns cause a spectrum of injuries, ranging from superficial to deep, leading to local damage and potential systemic effects based on the severity. It is imperative that owners understand importance of the early pet evaluation by professionals, or to provide first aid. Accurate clinical estimation is crucial for effective treatment and prognosis. Throughout history, the calculation of the affected body surface area of the animal was based on different methods in human medicine. Recent studies showed this method as inaccurate and new calculations were proposed. Because of the wide diversity, a completely accurate method is not established in veterinary medicine yet. Although standard treatment of burns is not established in veterinary medicine, the administration of analgesics, antibiotics, and fluid therapy is frequently recommended as essential. To stimulate wound healing and prevent excessive pain, wound moisturize is recommended as a part of treatment. We report the assessment and treatment of four days old third-degree thermal burn injury in an adult Pekingese dog.

Experimental and numerical study on local damage effect of ultra-early-strength reinforced concrete slabs (URCS) under contact explosion

UR50 ultra-early-strength cement-based self-compacting high-strength material has the advantage of short curing time and rapid development of early strength, which is an ideal material for rapid repair and construction of key facilities in wartime. In order to investigate the local damage characteristics of ultra-early-strength reinforced concrete slabs (URCS) under contact explosion thoroughly, 12 contact explosion tests were carried out on URCS cured for 28 days and 24 h with three reinforcement rates (0.23%, 0.41% and 0.79%) under 200 g, 400 g, 600 g and 800 g TNT mass by using TNT binding cube charge. The test results showed that the explosion resistance performance of URCS cured for 28 days under contact explosion was not much different from that cured for 24 h, and the variation of reinforcement rate within the conventional range had limited influence on the explosion resistance performance of URCS. Further, explicit dynamic finite element software LS-DYNA was used to simulate the local damage of URCS cured for 24 h under contact explosion, and the influence of slab thickness and TNT mass on local damage of 24-hour curing URCS was studied with validated numerical model, and the range of seismic collapse coefficients Kz for different failure modes of URCS under contact explosion was given.

Physics informed and data-based augmented learning in structural health diagnosis

Data-based diagnosis has been extensively addressed in the domain of structural health monitoring. Data exhibit patterns able to infer the existence of damaged areas, and in some cases to locate them. However, optimal predictive maintenance requires the ability to make fine predictions, which can be obtained by interrogating a model describing the systems under scrutiny. Thus, data is not only expected to enable diagnosis, but also to update the nominal model to incorporate the effects of localized damage, from data assimilation. Such a data-driven model enrichment can be performed by using different routes. In the present paper we propose an augmented physics-informed neural network procedure that allows updating the model, while completing the data collected by few sensors, using physics-informed NN and an appropriate regularized loss function.

Revealing and simulating the effect of hidden damage on local and full-field deformation behaviour of cast aluminium

Pores have been the main focus of quality assurance in castings. Latest research has shown that in aluminium castings pores can form only if there is existing entrainment damage, i.e., pores are merely the visible parts of the entrainment damage, and usually invisible damage is much more extensive. However, its effect on deformation behaviour has not been previously established or observed in-situ. This work applies 2D Digital Image Correlation (DIC) to an in-situ full-field stress-strain analysis of tensile samples with a non-conventional heterogeneous stress distribution. The observations reveal that the effect of hidden damage extends far beyond its impact on fracture behaviour and is responsible for initiating local strain concentrations during deformation. By extracting local stress-strain data, FE simulations have been performed to mimic the effect of local hidden damage on the heterogeneous stress-strain field. SEM and FIB-SEM analysis has been applied to investigate the cause for the strain concentrations. The combined results show that hidden damage in the form of oxide films is not only responsible for premature fracture, but also affects the deformation behaviour of tensile samples by introducing dispersed strain concentrations.

Effectiveness of endometrial scratching in infertility treatment with assisted reproductive technologies

Embryo implantation is a key factor limiting the effectiveness of assisted reproductive technologies, and depends on the quality of the blastocyst and the susceptibility of the endometrium. Various methods of treatment aimed at improving the receptivity of the uterine mucosa, including endometrial scratching, have been proposed. At the same time, the main mechanisms underlying this intervention remain unclear. Moreover, the optimal duration of exposure to the uterine mucosa and the groups of patients in which it can have a positive effect have not been determined. The study aims to investigate the main mechanisms and evaluate the effectiveness of local endometrial damage performed at various times before embryo transfer in the program of assisted reproductive technologies in women with and without a history of implantation failures based on the analysis of scientific literature. Clinical studies, systematic reviews and meta-analyses were studied in PubMed, Embase, Cochrane Library, Web of Science databases, Elsevier, Springer, Wiley publishers, on eLibrary, Research Gate platforms, in open sources of the scientific and educational segment of the Internet. The literature search was conducted by keywords: endometrial scratching, local endometrial damage, implantation failures, endometrial receptivity, assisted reproductive technologies, infertility. The search depth is 20 years. The main mechanisms of the effect of scratching on increasing endometrial receptivity include decidualization, the development of a local inflammatory reaction, as well as improved synchronization between the uterine mucosa and the transferred embryo by preventing premature maturation of the endometrium. Studies that showed a positive effect of local damage to the uterine mucosa were mainly conducted in patients with repeated implantation failures and with intervention in the luteal phase of the cycle preceding stimulation. At the same time, the work performed in a non-selective population of women and non-standardized by exposure time, in most cases, did not reveal the advantages of endometrial scratching. In this regard, additional qualitative randomized controlled trials with a large sample size and a clear identification of groups of patients for whom this intervention may benefit are required.

Effects of Local Denting and Fracture Damage on the Residual Longitudinal Strength of Box Girders

The residual strength of denting- and fracture-damaged box girders were experimentally and numerically investigated. The experiments were conducted under a pure bending moment using the four-point bending test method. The load, deflection, and strain were measured. The strains of the extension structures were also measured, and the frictional forces between the model and the supported round bar were estimated. Test models consisting of two groups were fabricated. These groups were designed to estimate the residual strength of denting- and fracture-damaged models. The damage was induced by releasing a striker using a drop-testing machine to consider the dynamic effect. Additionally, numerical analyses were performed via a nonlinear finite element analysis, where the measured initial imperfection data and welding residual stresses were considered. The ultimate longitudinal moments that considered the frictional force of the round bars were reduced by 12% (on average) compared with those obtained by neglecting the frictional forces.

Reinforced concrete slab under projectile impact – A review

This comprehensive review explores the intricate interplay between concrete structures and projectiles, crucial for both military and civil engineering applications. The study investigates diverse concrete compositions, reinforcement strategies, and projectile geometries used in impact scenarios. Material models, including Riedel-Thoma-Hiermaier (RHT), Holmquist-Johnson-Cook (HJC), and Xu et al., are examined for their effectiveness in simulating concrete's dynamic behavior under high strain rates. The analysis encompasses failure modes resulting from projectile impact, including scabbing, spalling, perforation, and punching, with empirical formulas predicting damage depths. The concept of a ballistic resistance limit is discussed, offering a predictive tool for assessing projectile resistance that is adaptable to various scenarios, including reinforcement considerations. The effectiveness of strategies such as reinforcement, prestressing, and layered configurations in minimizing damage and perforation velocity are highlighted. Consideration of local and global damage effects in assessing Reinforced Concrete Composite (RCC) structures' impact response is emphasized. The review concludes by suggesting future research directions to improve concrete resistance through empirical studies and advanced numerical simulations, thereby contributing to the advancement of protective engineering practices.

Localized Damage Identification in the Last Stage Low-Pressure Steam Turbine Blade Using Dynamic Parameter Measurements

Abstract Steam turbine blades are the important components in power system shaft lines subjected to severe temperatures, leading to low/high cycle fatigue failures. The transient conditions occurring during startup and shutdown events generate alternative stresses causing the fracture at the blade roots. The present work deals with the effect of localized damage on the vibration characteristics and damage identification study in the last stage low-pressure (LP) steam turbine blade. Initially, free vibration studies and transient analysis of the last row LP blade section are conducted using the finite element model. A crack near the root region is modeled by a torsional spring, whose stiffness is expressed in terms of crack depth ratio. Effects of crack depth ratio and location near the roots on the natural frequencies and transient response amplitudes are studied in detail. The relationship between the damage parameters and blade frequencies is established through the backpropagation neural network model.

Experimental and theoretical investigations on axial bearing capacity of steel angle members with local corrosion on their limb peaks

To investigate the effect of local corrosion damage on the bearing performance of steel angle members, a total of 21 specimens, with various slenderness ratios and corrosion levels, were prepared and subjected to axial compression. During the test, the load–displacement curves, load–strain histories, failure modes, and residual bearing capacity of the steel angles were experimentally obtained and analysed. After that, the finite element analysis (FEA) model, calibrated by the test results, was established to further reveal the failure mechanism of the corroded steel angles under axial compression. It was found that all the corroded steel angles finally failed under global buckling around the weak axis induced by local buckling, and their residual bearing capacities were negatively correlated with the widths and lengths of the local corrosion zones. However, for the angles with a large slenderness ratio or with a local corrosion length larger than 20% of the whole length, the effect of local corrosion on the residual bearing capacity gradually diminished. By using the equivalent cross-sectional area, a simplified design method was also proposed to evaluate the residual bearing capacity of the corroded steel angles, and the predictions agreed well with both the test and simulation results.

Understanding the approach to animals with thermal burns

Thermal burn injuries represent a spectrum of superficial to deep epidermal and dermal injury sustained after exposure to a liquid, solid or gaseous heat source. Severe thermal burns result in both local damage and systemic effects. In systemically compromised animals, managing major body system abnormalities takes priority over surgically managing the thermal burn. General principles of wound management are relevant to animals with thermal burns. The surgical approach will vary according to individual wound and patient factors. Adjunctive therapies, such as negative pressure wound therapy, are touched on. Further research into thermal burns in veterinary cases is warranted.

A Computational Investigation of Microstructural Damage of the Anterior Cruciate Ligament Under High Loading of the Knee Joint.

The anterior cruciate ligament plays a major role in maintaining the stability of the knee joint and is susceptible to injury under strenuous activity. Anterior cruciate ligament (ACL) injuries can lead to joint instability and complications such as osteoarthritis. Despite this, there is a lack of material models capable of predicting damage at a localized fiber level, hindering our ability to understand how damage develops in real-time. This work develops a continuum-damage material model of the ACL and applies the model to a finite element simulation of the knee undergoing high quadriceps tendon loading. Using quadriceps tendon loadings of 1000, 1500, and 2000 N, the development of microstructural damage within the ACL tissue was examined, and the effects of localized damage on the joint kinematics were investigated. Damage tended to develop in the midsubstance of the ACL in the present model in the anterior medial bundle region and could induce significant changes in the joint kinematics. Using this model, new insights into the development of ACL injury mechanisms can be investigated.

Local creep damage effects on subsequent low temperature fatigue crack growth behaviour of thick-walled pressure vessels

The influence of prior creep damage on the subsequent fatigue cracking behaviour of thick-walled pressure vessels has been thoroughly investigated in this study. Creep damage was introduced into fracture mechanics specimens by performing creep tests at 550 °C and stopping them after reaching a desired crack length. Using this experimental methodology, creep damage was successfully introduced ahead of the crack tip in the form of intergranular voids and microcracks. In order to assess the creep damage effects, in the absence of significant plasticity, on the structural integrity of thick-walled pressure vessels the material was uniformly pre-strained under compressive plastic deformation prior to the specimen manufacture, thus hardening the material. Fatigue tests were performed on specimens with and without creep damage and the results were compared with each other. Moreover, metallurgical investigations were conducted to understand the influence of microstructural damages, as a result of creep loading conditions, on the fatigue cracking behaviour of the material. The results from this study show a clear reduction in the fatigue cracking rate in the presence of creep damage local to the crack tip. The findings have been discussed in terms of the effects of static creep loading conditions and microstructural damages on the subsequent fatigue cracking behaviour under cyclic loading conditions.

A numerical chemo-micromechanical damage model of sulfate attack in cementitious materials

The sulfate attack (SA) of cementitious materials widely exists, which severely reduces the mechanical properties and durability of cementitious materials. However, few numerical SA damage models of cementitious materials have been comprehensively developed. The understanding and simulation of the chemo-mechanical behavior of cementitious materials are beneficial to better modeling, predictions and designs of underground structures. In this research, a numerical chemo-micromechanical damage model under the SA and loading is proposed to explore the cracking process of the cementitious materials based on the discrete element method (DEM). Some inherent characteristics of the chemical attack can be well considered in the proposed numerical model. The local damage effect can be simulated, as well as the sulfate corrosion degree and the material component. The performance of this proposed model is confirmed and validated by available experimental results. We examine the dependence of the strength and the elastic moduli of the cementitious material on: (a) the content of ettringite, (b) the distribution of ettringite, (c) the mechanical properties of the cementitious matrix, (d) the void ratio of the cementitious materials, (e) the confining pressure, and (f) the expansion coefficient of sulfate corrosion products. The softening and fluctuating phenomena are witnessed in the stress-strain curves. The failure mode of cementitious materials with the SA is different from that of specimens without the SA. The damage parameters of cementitious materials under the SA are examined in depth. The numerical results reveal that the proposed damage model is feasible and valuable in the modeling, predictions, applications and durability of chemo-mechanical sulfate attack problems in cementitious materials.

Physical explanation for vibro-acoustic modulation due to local and global nonlinearities in a structure and its experimental and numerical validation

This article introduces a simple physical explanation that demonstrates why a local or global nonlinearity in a structure causes amplitude modulation and phase modulation in the system response, when employing the vibro-acoustic modulation method for structural health monitoring (SHM) applications. The underlying major assumption and the explanation itself are validated experimentally and numerically. Afterwards, the explanation is used to demonstrate comprehensively why very different types of envelope functions can be observed in the system response, depending on the exciting ultrasonic carrier frequency ω. The beauty of the suggested explanation is that it does not only work for local nonlinearities, such as exhibited by defects, but also for any non-damage induced (local or global) nonlinearity in the system which can cause modulation as well. A physical understanding of cause and effect is of crucial importance here, because the modulation caused by non-damage induced nonlinearities might camouflage the effects of local damage that one is actually interested in during SHM applications.

Experimental study of collapse behavior of single-layer cylinder shells with infilled walls

To study the dynamic responses, dynamic characteristics and seismic performance of the single-layer cylinder shell considering the effect of infilled wall, several groups of shaking table tests were carried out. The acceleration responses, displacement responses and strain responses were measured in the tests, and the structural seismic performance was evaluated under different seismic motions and input principal directions. The mechanism of load redistribution was investigated to evaluate the local damage effect on the whole structural collapse and the progressive collapse resistance, and the test results were compared with those from the shaking table tests of the single-layer cylinder shell without the effect of infilled wall. The results show that the infilled wall changes the dynamic characteristics and dynamic behavior of the whole structure, and the damage of the infilled wall cause abrupt change of the dynamic response including the acceleration amplification effect and strain amplification effect. The collapse resistence of the structure is reduced because of the infilled walls, and the collapse pattern is also changed. The ductility of the single-layer cylinder shell structure is reduced, and this is conflict with the traditional view which believes the infilled wall will enhance the seismic resistence performance. The data and conclusion of this study will provide references to the evaluation of seismic resistance and engineering practices for cylinder shell structure.

ПСИХОФИЗИОЛОГИЧЕСКИЕ АСПЕКТЫ КЛИНИЧЕСКИ ВЫРАЖЕННЫХ НАРУШЕНИЙ ПСИХИЧЕСКОЙ АДАПТАЦИИ У БОЛЬНОЙ, ПОЛУЧИВШЕЙ МЕСТНОЕ ЛУЧЕВОЕ ПОРАЖЕНИЕ IV (КРАЙНЕ ТЯЖЕЛОЙ) СТЕПЕНИ (23 ГОДА НАБЛЮДЕНИЯ)

Purpose: To evaluate in dynamics the psychophysiological adaptation of a patient who received local radiation damage to the tissues of the left half of the chest IV (extremely severe) severity (23 years of observation).
 Material and methods: Patient KTS, 66 years old, as the main diagnosis are the effects of local radiation damage to the skin and underlying tissues of the left half of the chest from external radiation (about 3 % of body surface area) IV extremely severe. Before receiving a radiation injury, she was able-bodied and socially adapted, worked as a nurse. In 1996, she was diagnosed with stage I left breast cancer T1N0M0 stage I, in connection with which she underwent a sectoral resection of the mammary gland. Then the patient underwent a course of radiation therapy. By retrospective assessment, the total dose of therapeutic effect before the incident was 10 Gy. At the time of the next session of radiation therapy in connection with the breakdown of the apparatus, a sharp uncontrolled increase in the dose of ionizing radiation (more than 100 Gy) occurred, causing serious injury. The patient was admitted to the Institute of Biophysics Clinic on the 5th day. Psychophysiological research was carried out with the use of automated software and methodic complex «Expert», designed to study the personal characteristics of a person, cognitive and intellectual personality characteristics in 2001 – 2017 years.
 Results: The effects of local radiation damage to the skin and underlying tissues of the left half of the chest from external irradiation of IV (extremely severe) degree in the form of cicatricial-atrophic changes of the soft tissues, with no bone skeleton remain. Disorders of mental adaptation are expressed in the form of senesto-hypochondria disorders, autism of perception, demonstrativeness, apathetic depression and introversion. The most profound contribution to the reduction of the adaptation of the victim is brought about by the features of deep internal disharmony caused by contradictory combinations of demonstrativeness, schizoid traits, anxious depression and affective rigidity.
 Conclusion: The data obtained indicate that impaired mental adaptation is an integral part of the clinical picture of local radiation injuries, and reveal the urgent need not only of specific treatment of radiation injury, but also of psychotropic pharmacotherapy and psychotherapy.

Deformation and Damage Assessments of Two DP1000 Steels Using a Micromechanical Modelling Method

Damage characterization and micromechanical modelling in dual-phase (DP) steels have recently drawn attention, since any changes in the alloying elements or process route strongly influence the microstructural features, deformation behavior of the phases, and damage to the micro-mechanisms, and subsequently the particular mechanical properties of the material. This approach can be used to stablish microstructure–properties relationships. For instance, the effects of local damage from shear cutting on edge crack sensitivity in the following deformation process can be studied. This work evaluated the deformation and damage behaviors of two DP1000 steels using a microstructure-based approach to estimate the edge cracking resistance. Phase fraction, grain size, phase distribution, and texture were analyzed using electron backscatter diffraction and secondary electron detectors of a scanning electron microscope and employed in 3D representative volume elements. The deformation behavior of the ferrite phase was defined using a crystal plasticity model, which was calibrated through nanoindentation tests. Various loading conditions, including uniaxial tension, equi-biaxial tension, plane strain tension, and shearing, along with the maximum shear stress criterion were applied to investigate the damage initiation and describe the edge cracking sensitivity of the studied steels. The results revealed that a homogenous microstructure leads to homogenous stress–strain partitioning, delayed damage initiation, and high edge cracking resistance.

Altered Drop Jump Landing Biomechanics Following Eccentric Exercise-Induced Muscle Damage.

Limited research exists in the literature regarding the biomechanics of the jump-landing sequence in individuals that experience symptoms of muscle damage. The present study investigated the effects of knee localized muscle damage on sagittal plane landing biomechanics during drop vertical jump (DVJ). Thirteen regional level athletes performed five sets of 15 maximal eccentric voluntary contractions of the knee extensors of both legs at 60°/s. Pelvic and lower body kinematics and kinetics were measured pre- and 48 h post-eccentric exercise. The examination of muscle damage indicators included isometric torque, muscle soreness, and serum creatine kinase (CK) activity. The results revealed that all indicators changed significantly following eccentric exercise (p < 0.05). Peak knee and hip joint flexion as well as peak anterior pelvic tilt significantly increased, whereas vertical ground reaction force (GRF), internal knee extension moment, and knee joint stiffness significantly decreased during landing (p < 0.05). Therefore, the participants displayed a softer landing pattern following knee-localized eccentric exercise while being in a muscle-damaged state. This observation provides new insights on how the DVJ landing kinematics and kinetics alter to compensate the impaired function of the knee extensors following exercise-induced muscle damage (EIMD) and residual muscle soreness 48 h post-exercise.

Practical approach of linear hydro-elasticity effect on vessel with forward speed in the frequency domain

In this study, a practical approach to incorporate forward speed and hydro-elasticity effect in the frequency domain is developed. By utilizing the discrete-module-beam (DMB) method, flexible structures are partitioned into multiple rigid bodies that are connected by beam elements. The forward speed effect is taken into consideration in the multi-body hydrodynamics through the slender body and low uniform flow speed approximation, which is called the uniform flow approximation (due to no steady perturbation coupling term considered). By implementing the uniform flow approximation into the multi-body hydrodynamics formulation and then coupling it with the DMB method, any multi-rigid-body radiation–diffraction simulation tools can be extended to solve the linear hydro-elasticity problem with forward speed effect. The present numerical results compare well with published experimental and computational results, including a more direct but much more time-consuming FEM–BEM coupling method. By using the developed computer program, the increase of elastic response and change in dynamic bending moment are assessed for various wave lengths and forward speeds in the case of Wigley hull. The occurrence of hydro-elastic resonance at the first bending mode at certain forward speed is illustrated for a typical operational sea state. The forward speed also changes the wet mode shape, dynamic elastic response, and dynamic bending moment and its distribution along the ship. Encounter frequency, convective term in the pressure formulation and the m-terms contribute to their changes. The effect of local structural damage on the modal characteristics and the resulting hydro-elasticity is also investigated It needs to be noted that due to several approximations (e.g., uniform flow and free-surface approximations), care should be exercised when applying the proposed method.