Material Damage Research Articles

Dual-Modal Near-Infrared Organic Nanoparticles: Integrating Mild Hyperthermia Phototherapy with Fluorescence Imaging.

Our study seeks to develop dual-modal organic-nanoagents for cancer therapy and real-time fluorescence imaging, followed by their pre-clinical evaluation on a murine model. Integrating NIR molecular imaging with nanotechnology, our aim is to improve outcomes for early-stage cutaneous melanoma by offering more effective and less invasive methods. This approach has the potential to enhance both photothermal therapy (PTT) and Sentinel Lymph Node Biopsy (SLNB) procedures for melanoma patients. NIR-797-isothiocyanate was encapsulated in poly(D,L-lactide-co-glycolide) acid (PLGA) nanoparticles (NPs) using a two-step protocol, followed by thorough characterization, including assessing loading efficiency, fluorescence stability, and photothermal conversion. Biocompatibility and cellular uptake were tested in vitro on melanoma cells, while PTT assay, with real-time thermal monitoring, was performed in vivo on tumor-bearing mice under irradiation with an 808 nm laser. Finally, ex vivo fluorescence microscopy, histopathological assay, and TEM imaging were performed. Our PLGA NPs, with a diameter of 270 nm, negative charge, and 60% NIR-797 loading efficiency, demonstrated excellent stability and fluorescence properties, as well as efficient light-to-heat conversion. In vitro studies confirmed their biocompatibility and cellular internalization. In vivo experiments demonstrated their efficacy as photothermal agents, inducing mild hyperthermia with temperatures reaching up to 43.8 °C. Ex vivo microscopy of tumor tissue confirmed persistent NIR fluorescence and uniform distribution of the NPs. Histopathological and TEM assays revealed early apoptosis, immune cell response, ultrastructural damage, and intracellular material debris resulting from combined NP treatment and irradiation. Additionally, TEM analyses of irradiated zone margins showed attenuated cellular damage, highlighting the precision and effectiveness of our targeted treatment approach. Specifically tailored for dual-modal NIR functionality, our NPs offer a novel approach in cancer PTT and real-time fluorescence monitoring, signaling a promising avenue toward clinical translation.

Nonlinear interaction of Lamb waves with fatigue cracks in metal plates under the condition of phase-velocity mismatching

Abstract Nonlinear Lamb waves have been widely acknowledged as an efficient method for evaluating material damage at an early stage. However, due to the dispersive and multimode natures of Lamb waves, nonlinear Lamb waves with exact/approximate phase-velocity matching have been employed in previous research solely for the evaluation of fatigue cracks. Second harmonic Lamb waves can be generated from the contact acoustic nonlinearity (CAN) induced by the “breathing” effect of fatigue cracks. This paper presents a verification of the second harmonic S0 mode Lamb waves due to fatigue crack CAN, despite the mismatch in phase velocity between this mode and the primary S0 mode Lamb waves. This verification is achieved through both simulation and experiment. Consequently, the generation of double-frequency Lamb waves by fatigue cracks under conditions of phase velocity mismatching is validated. Furthermore, the phase-velocity mismatching method is anticipated to exclude material nonlinearity in the detection of fatigue cracks. This method offers a potential for accurate detection and evaluation of fatigue cracks.

Superior fracture resistance and topology-induced intrinsic toughening mechanism in 3D shell-based lattice metamaterials.

Lattice metamaterials have demonstrated remarkable mechanical properties at low densities. As these architected materials advance toward real-world applications, their tolerance for damage and defects becomes a limiting factor. However, a thorough understanding of the fracture resistance and fracture mechanisms in lattice metamaterials, particularly for the emerging shell-based lattices, has remained elusive. Here, using a combination of in situ fracture experiments and finite element simulations, we show that shell-based lattice metamaterials with Schwarz P minimal surface topology exhibit superior fracture resistance compared to conventional octet truss lattices, with average improvements in initiation toughness up to 150%. This superiority is attributed to the unique shell-based architecture that enables more efficient load transfer and higher energy dissipation through material damage, structural plasticity, and material plasticity. Our study reveals a topology-induced intrinsic toughening mechanism in shell-based lattices and highlights these architectures as a superior design route for creating lightweight and high-performance mechanical metamaterials.

- PENGGUNAAN LAGU “AKU MAU” PADA PRODUK MAINAN BONEKA “PUTRI ANISA HIJAB PERFUMED DOLL”

Copyright violations have occurred frequently over the years, with one prevalent issue being the unauthorized duplication of copyrighted works. A notable instance of this is the unauthorized use of the song "Aku Mau" in the "Putri Anisa Hijab Perfumed Doll" toy. This case examines the protection of the song "Aku Mau"'s creator in relation to the doll product and the considerations of the Commercial Court judges based on Law No. 28 of 2014 on Copyright. The research methodology used is normative legal research with a descriptive approach, drawing on secondary data to support primary data. Data was gathered through fieldwork and literature review, then analyzed qualitatively with conclusions drawn using deductive reasoning. The results of this research is that the actions by GO TOYS and PT. BINTANG CAHAYA KENCANA involved the unauthorized duplication of the song "Aku Mau" for commercial gain. The conclusion is that the judges’s decision was justified, as the DJKI copyright registration confirmed Inge Christiane as the rightful creator of the song "Aku Mau." Consequently, the Commercial Court judges ruled in favor of awarding partial material damages totaling Rp. 4,000,000,000.

Efficiency of state financial control: approaches to evaluation and conditions of increase

Unresolved problems of the development of state financial control slows down the positive impact of the socio-economic development of the country. In the conditions of martial law and a shortage of financial resources, impeccable state financial control acquires the characteristics of one of the main guarantors of the effective and transparent use of international financial aid. The efficiency of the DFC becomes the main indicator of effective management of public finances. The article examines approaches to the assessment of the effectiveness of DFC. It was established that the reduction of the volume of financial violations depends on a group of factors: the effectiveness of the control measure, the effectiveness of the state financial control body; the quality of the evidence base, which should be a factor of irreversible action in matters of compensation for material damage caused to the state; completeness of implementation of recommendations on elimination of established violations and prevention of their occurrence in the future; the level of professional competence of managers of public sector entities in the implementation of control powers. It was determined that the desired efficiency of the DFC depends on the quality of its legal, methodological and praxeological support. Achieving a significant impact on the indicators of the state sector of the national economy can also take place thanks to the improvement of the qualifications of managers of state sector entities.

Modelling and Characterisation of Orthotropic Damage in Aluminium Alloy 2024.

The aim of the work presented in this paper was development of a thermodynamically consistent constitutive model for orthotopic metals and determination of its parameters based on standard characterisation methods used in the aerospace industry. The model was derived with additive decomposition of the strain tensor and consisted of an elastic part, derived from Helmholtz free energy, Hill's thermodynamic potential, which controls evolution of plastic deformation, and damage orthotopic potential, which controls evolution of damage in material. Damage effects were incorporated using the continuum damage mechanics approach, with the effective stress and energy equivalence principle. Material characterisation and derivation of model parameters was conducted with standard specimens with a uniform cross-section, although a number of tests with non-uniform cross-sections were also conducted here. The tests were designed to assess the extent of damage in material over a range of plastic deformation values, where displacement was measured locally using digital image correlation. The new model was implemented as a user material subroutine in Abaqus and verified and validated against the experimental results for aerospace-grade aluminium alloy 2024-T3. Verification was conducted in a series of single element tests, designed to separately validate elasticity, plasticity and damage-related parts of the model. Validation at this stage of the development was based on comparison of the numerical results with experimental data obtained in the quasistatic characterisation tests, which illustrated the ability of the modelling approach to predict experimentally observed behaviour. A validated user material subroutine allows for efficient simulation-led design improvements of aluminium components, such as stiffened panels and the other thin-wall structures used in the aerospace industry.

Analysis of the behavior of structures under the effect of progressive rupture of a cavity

Abstract The ground movements related to the presence of old underground cavities are often damaging to structures and infrastructures. Considering these ground movements in calculations will prevent considerable human loss and material damage. Many areas, both in Algeria and in abroad, are prone to instability caused by ground rupture and the phenomenon of sinkhole progression. The objectives of this work are first to numerically simulate the process of cavity collapse and second to analyze the impact of cavity properties on structure stability. A finite element model was established to analyze the influence of several cavity parameters (dimensions, volume, and spacing). Validation of the model relied on comparing numerical results with experimental data from scientific research, as well as those from analytical approaches. Adequate correlation was achieved. The study allowed deriving mathematical equations relating to several parameters, including cavity dimensions and position in the soil, soil characteristics, and footing width. These results will be considered to reduce the risk of surface structure instability.

Effect of Load Cycling on High Temperature Creep of 316L Stainless Steel

For components in concentrating solar thermal plants, the creep mechanism will cause a significant portion of material damage to receivers, storage tanks, turbines and pipework. These components will undergo conditions where loads, temperature, or both load and temperature are not constatnly applied. This creep damage process will not resemble the constant load creep tests used to characterise creep of materials. Therefore, creep tests incorporating a load cycle were undertaken to obtain a better understanding of how high temperature materials respond to these cyclic conditions. These tests showed that when time under load was considered, creep undertaken under load cycling conditions were accelerated relative to constant load conditions. A modified Larson-Miller approach was used to assess this effect and determine an equivalent stress where constant load test data agrees with the cycled test data. This found that cycling the load was equivalent to if the system were under 3 and 7 MPa higher stress, for tests which were loaded for 12 hrs and 6 hrs per 24 hrs respectively. This could be a potential approach to simply and easily consider these load cycling effects for design and life analysis.

Optimization of Material Utilization by Developing a Reliable Design Criterion for Tool Construction in Cross-Wedge Rolling

The massive forming industry in Germany produces around 1.4 million parts every year, which are mainly used in safety-relevant areas such as the automotive industry. The production of these parts requires a considerable amount of energy, much of which remains unused and causes high CO2 emissions. An efficient approach to reduce these emissions and improve material utilization is cross-wedge rolling, which enables efficient material utilization but is limited by the so-called Mannesmann effect, which leads to unwanted material defects. This paper describes the development and validation of a safe design criterion for cross-wedge rolling tools in order to avoid material damage caused by the Mannesmann effect and thus increase resource efficiency in forging. Based on simulation-supported investigations and experimental tests, process maps are created for various materials. The validation is carried out both in an experimental test facility with real tools and in an industrial production facility, which leads to a significant reduction in excess material and CO2 emissions. The results show that the full resource potential of cross-wedge rolling can be exploited by optimizing process parameters and tool geometries.

Study of the dynamic impact spalling of ductile materials based on Gurson-type phase-field model

The formation of void damage and spalling failure in ductile metallic materials under strong impact is a well-established phenomenon. In aerospace and defense technology engineering design, understanding the spalling failure process and related mechanisms is of utmost importance. This paper develops an explicit Gurson-type phase-field model that can simulate the void evolution and spalling damage of three-dimensional ductile metallic materials under high-velocity impacts based on the study of Aldakheel et al.. The model incorporates the Gurson-type void evolution equation and the phase-field approach while taking into account the pressure-dependent bulk modulus and inertia effects. This model is used to study the main processes and mechanisms of impacted layer cracking of metals in different dimensions. Meanwhile based on the study of complex spallation cracking processes in metals in two and three dimensions, observing and proposing the formation mechanism of complex spallation cracking modes in materials due to lateral and edge (base angle) rarefied effects.

A phase-field gradient-based energy split for the modeling of brittle fracture under load reversal

In the phase-field modeling of fracture, the search for a physically reasonable and computationally feasible criterion to split the elastic energy density into fractions that may or may not contribute to crack propagation has been the subject of many recent studies. Within this context, we propose an energy split – or energy decomposition – aimed at accurately representing the evolution of a crack under load reversal. To this purpose, two key assumptions are made. First, the damage gradient direction is interpreted as being representative of the normal-to-crack direction, as already assumed in previous works in the literature. The second assumption consists of considering the sign of the projection of the stress tensor onto the damage gradient direction at a point as an indicator of whether this point should behave as an opening or as a closing crack. We associate the latter case (crack closing) to both (a) a complete recovery of elastic energy density of the intact material (i.e., perfectly rough crack surfaces) and (b) a zero crack driving force at that point. The first case (crack opening) is treated classically as a damageable material point at which damage can increase. The implementation of the proposed approach turns out to be remarkably simple and computationally robust. For the evaluation of the displacements and damage gradients at nodes, the classical Z2 technique is used, and a new effective and computationally convenient iterative strategy is implemented to guarantee convergence of the staggered scheme. Four examples are presented in order to assess the suitability of the present model by using both AT1 and AT2 regularization models. Results show the desired effect of limiting crack propagation to prevailing tensile states, as well as of recovering the initial intact stiffness upon load reversal, even when two of the most common energy splits fail.

Multiscale modeling of diffuse damage and localized cracking in quasi-brittle materials under compression with a quadratic friction law

The diffuse damage and localized cracking of quasi-brittle materials (i.e., rocks and concretes) under compression can be delineated by a matrix-microcrack system, wherein a solid matrix phase is weakened by a large number of randomly oriented and distributed microcracks, and the macroscopic cracking is formed by a progressive evolution of microcracks. Several homogenization-based multiscale models have been proposed to describe this matrix-microcrack system, but most of them are based on a linear friction law on the microcrack surface, rendering a linear strength criterion. In this paper, we propose a new quadratic friction law within the local multiscale friction-damage (LMFD) model to capture the plastic distortion due to frictional sliding along the rough microcrack surface. Following that, a macroscopic Ottosen-type nonlinear strength criterion is rationally derived with up-scaling friction-damage coupling analysis. An enhanced semi-implicit return mapping (ESRM) algorithm with a substepping scheme is then developed to integrate the complex nonlinear constitutive model. The performance of LMFD model is evaluated compared to a wide range of experimental data on plain concretes, and the robustness of ESRM algorithm is assessed through a series of numerical tests. Subsequently, to effectively describe the localized cracking process, a regularization scheme is proposed by combining the phase-field model with the established LMFD model, and the discretization independent crack localization is numerically verified.

Micromechanical response of graphene coating on nt-TiAl under nanoindentation

The nanoindentation response of graphene (Gr) coating on nanotwin titanium-aluminum (nt-TiAl) matrix composites was studied using molecular dynamics (MD) simulation. The indentation velocity, twin boundary spacing, and parallel and vertical Z-axes are studied. The results show that the bearing capacity and hardness of Gr coating is significantly higher than that after coating failure, and the load-displacement curve shows the same phenomenon. Damage to the substrate material at varying speeds is indicated by atomic aggregation near the Gr coating, with the center of aggregation showing a negative correlation with indentation velocity. The matrix's damaged area is larger when the twin layer is perpendicular to the Z-axis and deeper when parallel, showing that the twin structure limits material damage by hindering dislocation expansion. Moreover, the presence of Gr coating delayed the matrix's plastic deformation process. This delay effect significantly improves the mechanical properties of composites, which have potential applications in aerospace.

Electrical characterization of freeze-thaw damage in saturated concrete and its interfacial transition zones

Determining the freeze-thaw (F-T) damage of the interfacial transition zone (ITZ) is crucial to understanding the mechanism of F-T in concrete and improving its frost resistance. In this paper, the F-T damage of saturated concrete/mortar and ITZ is characterized using AC impedance spectroscopy, and the micro-mechanisms of F-T damage in cement-based materials (CBMs) are summarized. Firstly, the damage factor was defined by the effective resistivity of the CBMs, and a correlation between the damage factor and the compressive strength loss was established. The F-T damage process was divided into a damage development stage and a damage stabilization stage based on the damage factor and fractal dimension. Then, the effective resistivity separation formula was proposed to calculate the ITZ effective resistivity, and the ITZ damage factor was calculated for non-destructive quantitative characterization of the F-T damage in the ITZ. Finally, the microscopic mechanism of F-T damage in CBMs and their ITZs was summarized based on damage factor, fractal dimension, super depth of field microscopy, and nanoindentation. The results showed a linear relationship between the damage factor and compressive strength loss (Lc = 0.176Er+0.030); the ITZ had damage factors of 80 % and 70 %, which were 1.6 and 1.4 times higher than those of the matrix, respectively; F-T cycles produce micro-damage, part of which connects with the disconnected pores to form connected pores, the micro-damage extends and accumulates along the surface of the aggregates, leading to ITZ debonding from aggregate and deterioration of the mechanical properties.

Nonlinear finite element damage analysis of laminated shells by Carrera Unified Formulation

The paper presents a comprehensive study on the nonlinear finite element analysis of laminated shells, employing the Carrera Unified Formulation (CUF) in conjunction with a progressive damage model developed by Tita et al. (2008). This research focuses on accurately predicting the behavior of laminated composite structures under progressive damage. The model accounts for both polymer matrix and fiber failures, and the numerical implementation and simulations are performed using MATLAB. The study validates the proposed framework by comparing the numerical results with experimental data, demonstrating a good agreement and thus confirming the model’s capability to capture the nonlinear behavior of laminated shells during damage progression. The research also highlights the importance of the CUF in providing a versatile approach to finite element analysis, allowing for different families of elements and, thickness expansions and use of failure criteria that consider out of plane stresses, which can be particularly useful for a more detailed and physically consistent analysis of damage in composite materials.

Peridynamic study on thermomechanical damage of the rail during wheel idling

Wheel idling is an extreme sliding contact scenario that accelerates rail failure. Using temperature-dependent elastoplastic materials, a peridynamic (PD) model for wheel-rail contact was developed to investigate the thermomechanical damage behavior of rails during wheel idling. Numerical simulations of loading and unloading during wheel idling under different loads were performed, and the results of contact stress, temperature, plastic deformation, and material damage were obtained and analyzed. During loading, the temperature of the rail surface increases rapidly to over 1200 °C, which is well above the austenitization temperature. The intense thermal softening caused by high temperatures deteriorates the wheel-rail contact relationship and leads to a surge in plastic deformation. The softened surface material was continuously removed by the contact load, leading to severe wear damage, and the wear depth increased significantly with the load and idling time. The wear coefficients for the Archard wear model were derived using the wear results from the PD model. During unloading, the surface material cools rapidly at a rate of 1400°C/s through heat transfer into the rail, undergoing martensitic transformation and forming a brittle and hard white etching layer. The thickness of the WEL decreases as the wear depth increases.

Scutellaria baicalensis Polysaccharide-Mediated Green Synthesis of Smaller Silver Nanoparticles with Enhanced Antimicrobial and Antibiofilm Activity.

Silver nanoparticles (AgNPs) have attracted widespread attention in multidrug-resistant bacterial infections. However, the application of AgNPs synthesized by conventional methods is restricted by its high costs, toxicity, and poor stability. Herein, a water-soluble polysaccharide (Scutellaria baicalensis polysaccharide, SBP) rich in reducing sugars was used as both the reductant and stabilizer to greenly synthesize spherical AgNPs@SBP with smaller particle sizes (11.18 ± 2.50 nm) and higher negative zeta potential (-23.05 ± 2.76 mV), which was favorable to enhance its antimicrobial activity and improve pH and thermal stability. Besides, SBP facilitated the adhesion and penetration of AgNPs@SBP to methicillin-resistant Staphylococcus aureus (MRSA) and carbapenem-resistant Escherichia coli (CREC), thus significantly enhancing its antibacterial activity (increased by 32-fold and 64-fold, respectively). Likewise, AgNPs@SBP at a low concentration (7.8 μg/mL) could effectively penetrate and inhibit nearly 90% of MRSA and CREC biofilm formation. Antimicrobial mechanism studies showed that AgNPs@SBP could lead to more severe cell membrane damage and genetic material leakage by upregulating reactive oxygen species and depolarizing mitochondrial membrane potential, ultimately resulting in the apoptosis of bacteria. Overall, the wrapping of SBP significantly enhanced the antibacterial and antibiofilm activity of AgNPs, which possessed great potential in the prevention and treatment of multidrug-resistant bacterial infections.

Analysis on failure test and evaluation about refueling receptacle of onboard hydrogen system

ABSTRACT As the key component of the onboard hydrogen system, the service life and failure problem of the refueling receptacle easily leads to the hydrogen leakage accident which give rise to the suffocation, the frostbite, the burns, and the impact injuries. The typical hydrogen leakage accidents include the accidental leakage, the ignition, the deflagration, and the explosion. Therefore, the failure test and evaluation problem about the refueling receptacle is focused on. In this paper, the failure test and evaluation about the refueling receptacle covering the vibration resistance performance, the temperature resistance performance, and the durability was studied. First, the failure mechanisms of the refueling receptacle involving the vibration, the temperature, and the durability based on the vehicle operating conditions were clarified. Second, according to the test experience and the vehicle operating condition, the test methods about the failure phenomenon of the refueling receptacle were established, respectively. Finally, the failure test results of the refueling receptacle were analyzed. The failure of the refueling receptacle may caused by the aging and failure of sealing element, the metal creep aging and material damage, the decline in the contact stress at the low-temperature connection, the loose connection, and the internal structural ectopia.

Fatigue analysis of spherulitic semi‐crystalline polymers: Unveiling the effects of microstructure and defect

AbstractA micromechanical model considering the spherulite structure of semi‐crystalline polymers was established in this study. The micro stress–strain histories were captured by combining the constitutive equations and multi‐axial fatigue criterion. The continuous damage theory was employed to describe the degradation of material properties during cycle loading. Based on the proposed model, the effects of microstructure features, such as grain anisotropy, defects, and crystallinity, on the fatigue performance was examined under multi‐axial loading condition. The local material degradation and damage accumulation were then focused on to understand the underlying fatigue mechanisms with various microstructures. Meanwhile, the crack initiation site was precisely predicted and discussed. This research provides theoretical support for understanding the failure mechanisms of spherulitic semi‐crystalline polymers, deepening the understanding of associated microstructural characteristics and strengthening the anti‐fatigue design of semi‐crystalline polymers.

Temperature field in the crack-free ductile dry grinding of fused silica based on wheel wear topographies

Fused silica is an excellent window material widely used in ultraviolet transmission optical system. Crack-free ductile dry grinding is a novel method for the efficient fabrication of fused silica. The grinding temperature field has an important influence on the grinding process. However, most previous studies assumed that the grinding temperature was independent of the wheel’s wear. In this paper, a temperature field model of the ductile dry grinding of fused silica is developed based on wheel wear topographies. Simulated wheel topographies with the same statistical parameters as the realistic wheel wear topographies are reconstructed based on the convolution filtering and Johnson transformation algorithm. The theoretical temperature field is the superposition of the thermal effects induced by effective cutting grain point heat sources extracted from the simulated wheel topographies. The theoretical prediction accuracy of the wheel-workpiece contact zone is validated by an infrared radiation transmission method. This model not only provides opportunity to explore the material removal mechanisms and improve the surface generation quality of fused silica during the wear process of the wheel, but also could be extended to provide the basis for the utilization of grinding heat or prevention of grinding thermal damage for other isotropic materials.