Material Damage Research Articles

Photoluminescence and Raman spectroscopy of wide bandgap semiconductors damaged by deep-UV laser irradiation

The effects of a pulsed, focused, deep-UV (4.66 eV) laser on wide and ultra-wide bandgap semiconductors were investigated with photoluminescence (PL) and Raman spectroscopy. Three semiconductor single crystals were studied: silicon carbide (6H-SiC), gallium nitride (GaN), and gallium oxide (β-Ga2O3). Atomic emission lines from neutral Ga or Si were observed during the laser-damage process. For all three semiconductors, PL mapping (3.49 eV laser excitation) of the damaged material revealed visible emission bands in the 2.6–2.8 eV range, attributed to point defects. Raman spectra (2.33 eV excitation) showed a reduction in the Raman peak intensities in the damaged region, along with weak PL bands around 1.9–2.1 eV.

Contribution of the Self‐Heating Method in the Characterization of the Fatigue Damage of Materials With Defects Resulting From Additive Manufacturing

ABSTRACTThis paper investigates the ability of the self‐heating method to characterize the fatigue behavior of 316L stainless steel produced by Laser Powder Bed Fusion. Nearly dense cylinders are built vertically using various process parameters corresponding to various volumetric energy densities. Fatigue specimens are then machined from these cylinders and polished. Fully reversed tension–compression fatigue tests (R = −1) are conducted. The self‐heating method is used for the estimation of the fatigue limits. These fatigue limits are compared to results obtained from S‐N curves in the high cycle regime. Whatever the set of process parameters, the self‐heating curves show three distinct domains of heat dissipation. Thanks to microstructure analysis, fractographic observations, and correlations with S–N curves, these domains can be closely linked to damage mechanisms associated or not with defects.

Comparison of low-velocity impact damage in laminated composites for two thermoplastic material systems

Aircraft manufacturers are investigating thermoplastic material systems to produce parts more quickly and efficiently. Detailed damage data is needed to evaluate existing damage analysis methods, developed for thermoset materials, to predict damage in thermoplastic materials. Damage maps were created for two thermoplastic material systems subjected to low-velocity impact over a range of impact energies. In this paper, the damage maps were used to investigate and compare the damage response of the different material systems. Impact specimens were manufactured from TC1225 LMPAEK T700G from Toray Industries and APC AS4D/PEKK-FC from Solvay. The effect of the degree of crystallinity on the damage response was also investigated using a third set of specimens manufactured using the Toray material and a quenching process. Using a combination of data obtained from X-ray computed tomography and ultrasonic testing, damage maps were created for every interface and ply for selected specimens showing matrix cracks, delamination outlines, and fractured fibers. The LMPAEK specimens were found to have fewer and smaller delaminations than the PEKK specimens for impacts at the same energy. However, the LMPAEK specimens contained a larger number of fiber breaks. A similar trend was observed when comparing low-crystallinity LMPAEK specimens with the baseline LMPAEK specimens. The LMPAEK specimens often contained lines of fiber fractures in near-surface plies emanating from the contact region that were not present in the PEKK specimens. The different damage responses may indicate that the material selection will be a function of the application and loading.

ANÁLISE DOS PRESSUPOSTOS DA RESPONSABILIDADE CIVIL DOS BANCOS NOS CONTRATOS DE VENDAS CASADAS

This paper explores the concept of moral and material damages, highlighting their compensatory, punitive and preventive functions, with a focus on the application of the law in cases of defective services in the Brazilian legal context, especially in the Small Claims Courts of Amazonas. It analyzes the historical development of consumer law and the role of Small Claims Courts in promoting swift and accessible justice, highlighting the importance of the principles of transparency, objective good faith and equity in consumer relations. The research uses a doctrinal and jurisprudential approach to demonstrate the effectiveness of tied selling as a tool to curb harmful practices and relieve the burden on the judicial system, promoting a fairer and more responsible business environment. It is concluded that the rigorous application of punitive damages contributes significantly to the protection of consumer rights, strengthening the civil liability system and social justice in Brazil.

Dual-Modal Fusion PRI-SWT Model for Eddy Current Detection of Cracks, Delamination, and Impact Damage in Carbon Fiber-Reinforced Plastic Materials

Carbon fiber-reinforced plastic (CFRP) composites are prone to damage during both manufacturing and operational phases, making the classification and identification of defects critical for maintaining structural integrity. This paper presents a novel dual-modal feature classification approach for the eddy current detection of CFRP defects, utilizing a Parallel Real–Imaginary/Swin Transformer (PRI-SWT) model. Built using the Transformer architecture, the PRI-SWT model effectively integrates the real and imaginary components of sinusoidal voltage signals, demonstrating a significant performance improvement over traditional classification methods such as Support Vector Machine (SVM) and Vision Transformer (ViT). The proposed model achieved a classification accuracy exceeding 95%, highlighting its superior capability in terms of addressing the complexities of defect detection. Furthermore, the influence of key factors—including the real–imaginary fusion layer, the number of layers, the window shift size, and the model’s scale—on the classification performance of the PRI-SWT model was systematically evaluated.

The Use of Phosphonates to Inhibit Salt Crystallization: A Laboratory Study for the Sustainable Conservation of Mural Paintings in the Hypogea Context

This research is focused on the laboratory study of salt crystallization inhibitor products as new materials for conservation treatments which can be applied to mortars and painted plasters; as is well known, salt crystallization is one of the most frequent causes of decay processes on decorated architectural surfaces in a wide range of environments. Specifically, the study targets the field of the preventive conservation of mural paintings within rupestrian heritage sites. For the first time, systematic investigations were performed on mock-ups made of plaster painted with two different pigments: yellow ochre and carbon black. Two types of phosphonate inhibitors, PBTC (2-phosphonobutane-1,2,4-tricarboxylic acid) and ATMP (aminotris (methylene phosphonic acid)), were chosen and applied at two different concentrations. Given the limited literature available, and the presence of pigments potentially sensitive to treatment with salt inhibitors, preliminary tests were required. Their effects on the chromatic features of the pigments were evaluated visually and using colorimetry. The changes in the behaviour of water circulation in the mortar resulting from the treatments were evaluated through water vapour permeability and absorption tests. Accelerated crystallization experiments were carried out to assess how inhibitors could influence the growth of salts and the resulting material damage. The latter was carried out by employing sodium sulphate and calcium sulphate solutions, quantifying the damage to the specimens through material loss in weight and the percentage of painted surface loss. Based on the overall results, the product with the best performance was identified was ATMP 0.1% (by volume) in deionized water. The obtained results show that salt inhibitor treatments are promising for in situ application and could represent an innovative approach to promote the sustainable conservation of mural painting, particularly those located in hypogeal contexts, where the salt supply cannot be removed and slowing the growth of salts and/or changing their crystalline habitus may be effective in limiting their damage.

Lightning ablation damage and residual bending performances of scarf-repaired composite laminates with copper mesh protection

The copper mesh provides effective lightning strike protection for composite structures, while its efficiency can be compromised in scarf-repaired composite structures. In this study, after verified by test results, a numerical analysis procedure was employed to predict the lightning ablation damage and residual bending performances of scarf-repaired composite laminates with copper mesh protection. Initially, the ablation damage and bending damage mechanisms of good repaired and poor repaired composite laminates were analyzed. Then, the impact of lightning strike attachment position and repair design parameters including overlap length and thickness of adhesive layer on the lighting protection performances was investigated. The results indicate that ablation damage of composite and adhesive materials near the repair area significantly compromises structural integrity and reduces the bending strength. The predominant bending failure mode of scarf-repaired woven composite laminates after lightning strike is fiber failure in warp direction, accompanied by small areas of matrix failure and delamination failure. The reestablishment level of the electrical path varies with overlap length and thickness of adhesive layer, subsequently affecting the ablation damage area and depth. This study can provide a reference for the design and process control of scarf-repair in copper mesh protected composite structures.

An Attempt to Predict Transparent Armor Ballistic Performance through Quasi-Static Punch Shear Test

Abstract Background Transparent armor systems are traditionally designed following a trial-and-error approach, which involves high development costs associated with ballistic testing. This research article presents a novel methodology, termed quasi-static multi-punch shear testing, within the domain of transparent armor systems. Objective The primary aim is to establish a correlation between multi-hit ballistic tests at Level III-A according to the NIJ 0108.01 standard, achieved through an adaptation of the single-shot ballistic limit methodology, and the quasi-static multi-punch shear testing. The objective is to utilize a simple experimental methodology that provides insights into the multi-hit ballistic behavior of transparent armors. Methods Parameters such as absorbed energy and observed damage mechanisms were utilized to assess the potential relationship between these tests. Transparent armor samples that underwent testing using the quasi-static multi-punch shear test were subsequently cross-sectioned using a water jet cutting machine to facilitate visualization of material damage. In addition, drawing on insights from quasi-static multi-punch shear testing results, the K-means clustering algorithm was employed to predict the likelihood of a specific transparent armor system passing a multi-hit ballistic test. Results Various damage mechanisms were observed as a function of the punch displacement, and correlations were made with the load–displacement curves. Furthermore, the implementation of the K-means clustering algorithm successfully classified transparent armor into two groups: those that passed the ballistic test and those that did not. Conclusions This research significantly advances understanding of transparent armor system behavior under multi-hit conditions and offers a promising predictive tool for evaluating their performance through straightforward and cost-effective experimentation.

Self-Reporting Multiple Microscopic Stresses Through Tunable Microcapsule Arrays.

Self-reporting materials have emerged as a promising tool for real-time monitoring of stress and damage in structural materials. When critical stress is applied to these materials, an optical response is triggered - for example by dye release, or molecular cleavage. A key challenge is to extend these systems to respond to multiple different stress levels. To achieve this, a novel microcapsule-based assembly strategy is presented. Microfluidic synthesis is used to create microcapsules that release dye at a precise level of applied force. Subsequently, capillary assembly is used to combine microcapsules with different stress-responsiveness and different fluorescent dyes into chains, which are uniformly patterned into regular arrays, and embed these into the self-reporting materials. Through indentation experiments, it is shown that these materials can distinguish and record spatially resolved local stresses based on the fluorescence emitted upon microcapsule rupture. Crucially, the technique's accuracy is significantly improved when microcapsules are spatially organized within the material. This versatile technique can be applied to a range of different materials, via the use of thin coatings containing the regularly patterned microcapsule chains.

Prognosis of reflective pavement cracking development with Bayesian updating and surrogate models

ABSTRACT The main objective of this study is to establish an integrated prognostic method for predicting the development of thermal-induced reflective cracking in asphalt overlay on concrete pavement. The integrated prognosis process for crack growth is developed on the modified Paris’ law and includes three steps: (1) calculation of J-integral; (2) Bayesian updating of crack growth parameters and (3) prediction of remaining life. Finite element modelling (FEM) was conducted to calculate J-integrals at different crack depths and cold weather conditions. A surrogate model was built based on the original Kriging method and it shows high accuracy in predicting J-integrals from maximum air temperature, temperature drop and crack depth. The Bayesian updating process starts from the laboratory-measured distribution of fracture model parameters (A and n) in Paris’ Law and converges to the true values to match the measured crack depths at different loading cycles from field inspection. On the other hand, the consideration of material damage in asphalt overlay avoids over-estimation of remaining loading cycles for reflective cracking to reach the pavement surface. Further study is recommended to accurately assess in-situ pavement modulus and detect crack depth over concrete joints for implementation of the proposed prognostics method.

Numerical simulation of strengthening/deterioration and damage development of cementitious materials under sulfate attack environment

Cementitious materials exposed to sulfate environments often suffer from the combined effects of external sulfate attack and dry wet cycling. In order to predict the long-term performance of cement-based materials in sulfur rich environments, this paper aims to establish a numerical model that can reasonably characterize the degradation process of cementitious materials in sulfate environments. Using this model, we can address durability problems common to cementitious materials in real sulphate environments, such as determining the degree of corrosion, predicting the durability life of materials, and calculating the time to failure. The model consists of three parts: transportation, chemical reactions, and material damage. We establish the degradation model for cement-based materials in sulfate environments by considering ion diffusion, water convection, chemical reactions, accumulation of corrosion products, and the development of material strengthening/degradation. Compared with existing sulfate corrosion models, this model not only considers ettringite, but also takes into account the volume changes of gypsum formation, calcium leaching, and salt crystallization precipitation, which can more reasonably simulate the sulfate corrosion process in real environments. The model can reasonably simulate the distribution pattern of ion concentration, hydration products and corrosion products in the cementitious material, and on this basis calculate the porosity of the cementitious material. In order to make the simulation results more applicable to experimental and non-destructive testing results, the model uses easily obtainable relative dynamic elastic modulus to evaluate the degree of material strengthening/degradation and predict the durability life of the material.

New-Concept Metal-Based Artificial SEI Film of Polyimide Anode Material in Dual-Ion Batteries.

Organic material polyimides (PI) are widely used in secondary batteries due to green safety, renewables, and structural designability. However, problems such as low conductivity and structural damage of polyimide electrode materials seriously limit its practical application. Herein, an innovative in situ modification method with CaCl2 is used to construct pure Al metal-based artificial SEI film on the surface of PI to improve the electrochemical performance of organic dual-ion batteries. Compared with the pure PI material, it has a noticeable improvement in cycle performance. Importantly, characterization results of the physicochemical analysis show that the pure Al metal-based artificial SEI film formed in situ on the surface of the PI material plays a key role in isolating and improving the electrochemical performance of PI anode materials. The innovative approach offers an efficacious strategy to construct pure metal-based artificial SEI films for the practical implementation of organic batteries.

INTERNATIONAL STANDARDS GOVERNING INDIVIDUAL REHABILITATION

In this article, the international documents, the international standards established in them, on the rehabilitation of the victims of the actions (inaction) and decisions of the bodies and officials authorized to conduct criminal proceedings, compensation for the material and moral damages caused to them, and their provision by the state have been studied and analyzed. In particular, the author presents analytical views on the measures that should be taken to rehabilitate, compensate for the harm caused to, and integrate into society those whose human rights and freedoms have been unlawfully restricted or deprived, unjustly or unjustly convicted, unjustly arrested, or imprisoned, in declarations, conventions, and international pacts adopted by the UN and other international organizations.

Mapping structural damage to material damage for analysis of urban buildings considering actual damage states

Mapping structural damage to material damage for analysis of urban buildings considering actual damage states

Development of an Optimized Accident Prediction Model for Construction Safety Using Big Data Analysis

Background and objective: The objective of this study was to develop an intuitive accident prediction model that can be readily applied at construction sites to effectively reduce the incidence of accidents through the analysis of construction accident data.Methods: These accidents significantly contribute to the construction industry's overall accident rate. Accident types were categorized into fatalities, injuries, and material damages to construct the accident prediction model. A total of 24 factors were considered across eight major variables, which were identified during the first and second phases of data preprocessing to analyze construction accident big data. Machine learning techniques were employed, specifically supervised learning and ensemble learning, to identify the optimal predictive model.Results: Among the models tested, XGBoost emerged as the most effective due to its highly balanced accuracy, even in the presence of class imbalance.Conclusion: The implementation of the XGBoost accident prediction model, along with the feature importance codes developed in this study, enables the prediction of accident types for specific tasks performed at construction sites. This predictive capability is expected to inform the implementation of targeted accident prevention measures, such as enhancing safety protocols or adjusting work procedures based on the prediction outcomes.

Study of acute and subacute toxicities and genotoxic and mutagenic potentials of the lyophilized extract of Campomanesia sessiliflora (O.Berg) mattos leaves in wistar rats

Campomanesia sessiliflora (O.Berg) Mattos is a Brazilian native plant species used in a popular medicinal tea for treating gastrointestinal, urinary, and dermatological pathologies. This study evaluated the toxicity of Campomanesia sessiliflora (O.Berg) Mattos via acute and subacute toxicity tests. It also analyzed mutagenic and genotoxic potentials by the micronucleus test, which detects genetic material damage indicating mutagenicity, and the comet assay, which assesses DNA damage levels as a genotoxicity indicator. The plant extract initially originated from the ultrasonic maceration of Campomanesia sessiliflora (O.Berg) Mattos leaves in a hydroethanolic solution. The involved animals were adult Wistar rats. Ten females were available to evaluate acute toxicity and estimate the LD50, receiving a dose of 2000 mg/kg. The subacute toxicity evaluation used 35 females and 35 males divided into seven groups: negative control (saline control – SC), positive control (cyclophosphamide control – CC), 125 mg/kg (125), 250 mg/kg (250), 500 mg/kg (500), 1000 mg/kg (1000), and the satellite group (ST). Genotoxicity and mutagenicity experiments applied bone marrow micronucleus and comet assays. Acute and subacute toxicity tests did not present behavioral, physical, and physiological changes (p≥0.05). Administering the Campomanesia sessiliflora (O.Berg) Mattos extract reduced spleen size in male and female animals, without histopathological changes. However, doses above 500 mg/kg showed significant genotoxic and mutagenic effects in the comet and micronucleus assays compared to the control group. The extract did not exhibit acute or subacute toxicity, but doses higher than 500 mg/kg indicated some level of genotoxicity and mutagenicity.

A Fractal Study on Random Distribution of Recycled Concrete and Its Influence on Failure Characteristics

In order to quantitatively describe the influence of aggregate distribution on crack development and peak stress of recycled aggregate concrete, a multifractal spectrum theory was proposed to quantitatively characterize aggregate distribution in specimens. A mesomechanical model of reclaimed aggregate concrete mixed with natural aggregate and artificial aggregate was constructed. Numerical simulation tests were conducted on the uniaxial compression mechanical behavior of 25 groups of sample models with the same proportion and different aggregate distribution forms. Based on the box dimension theory, the multiple fractal spectrum method was used to quantitatively characterize the aggregate distribution form, and the key factors affecting cracks were explored based on the gray correlation degree. The research results show that the aggregate distribution in recycled aggregate concrete has multifractal characteristics. The multifractal spectrum was used to effectively characterize the aggregate distribution pattern, which can enlarge local details and provide new ideas for the quantitative analysis of the damage mode of recycled concrete. Secondly, by establishing a statistical model of the correlation between the multifractal spectrum width of the aggregate distribution pattern and the crack distribution box dimension, it was found that there was a positive correlation between the two, that is, the greater the multifractal spectrum width of the aggregate distribution pattern, the greater the crack box dimension, and the more complex the crack distribution. The complexity of aggregate distribution is closely related to the irregularity and complexity of mesoscopic failure crack propagation in recycled concrete specimens. In addition, gray correlation theory was applied to analyze the key factors affecting the formation of cracks in the specimens. The results showed that aggregate distribution had a first-order correlation with crack formation, and changes in aggregate distribution were an important factor affecting the performance of recycled concrete. Secondly, the poor mechanical properties of NAITZ led to obvious material damage, while NCA and MZ had a significant impact on the skeleton effect in the stress–strain process due to their large areas. This study deepens people’s understanding of the damage characteristics and cracking failure modes of recycled concrete. The study verifies the feasibility of the application of recycled aggregates and provides a valuable reference for engineering practice.

Compressive resistance of thin-walled pultruded GFRP profiles: The role of delamination examined through experiments and FE simulations

Significant efforts have been made in the last decades to develop design rules and guidelines for composite structures, meeting the increasing interest in pultruded glass fibre reinforced profiles (GFRP) by the construction industry. One aspect that has been difficult to address is the crushing resistance of these profiles, with previous research indicating that the design equations are not conservative, predicting much higher resistances than those obtained in experimental tests. This paper explores the possibility that crushing resistance is governed by tensile failure in the through-thickness direction of the laminates, by Poisson effect, and proposes modifications to a previously presented material damage model to account for this in finite element (FE) simulations. Compressive experimental tests were conducted in stub-column specimens, with 5 different open-section configurations, obtained from three different producers. The test results were compared to analytical and FE simulations, confirming that the former grossly overestimate the resistance, while the latter, with the proposed damage model, compare well with experimental results.

Efficient Metal Corrosion Area Detection Model Combining Convolution and Transformer

In the context of rapid industrialization, efficiently detecting metal corrosion areas has become a critical task in preventing material damage. Unlike conventional semantic segmentation targets, metal corrosion characteristics vary significantly in color, texture, and size. Traditional image segmentation methods need improvement in scenarios involving occlusions, shadows, and defects. This paper proposes a convolution and sequence encoding combined network, MCD-Net, for metal corrosion area segmentation. First, a visual Transformer sequence encoder is introduced into the convolutional encoder–decoder network to enhance global information processing capabilities and establish long-range feature dependencies. A feature fusion method based on an attention module is proposed to enhance the model’s ability to recognize corrosion boundaries, thereby enhancing segmentation accuracy and model robustness. Finally, in the model’s decoding stage, a score-based multi-scale feature enhancement method is employed to emphasize significant features in the corrosion areas. Experimental results indicate that this method attained an F1 score of 84.53% on a public corrosion dataset, demonstrating the model’s deeper understanding and reasoning capabilities for shadow and defect features, as well as excellent noise resistance performance.

Spatiotemporal variability of flash floods and their human impacts in the Czech Republic during the 2001–2023 period

Abstract. Flash floods, characterized by their sudden onset, extreme discharge, short duration, material damage, and human loss, represent a significant natural hazard. Not well covered by standard hydrological observations, flash flood data can primarily be derived from various types of documentary evidence. This evidence served as the main data source for creating a flash flood database for the Czech Republic from 2001 to 2023. This database enabled detailed analysis of different aspects of flash floods. The annual series of 233 flash flood events, 160 flash flood days, and 424 affected municipalities showed significant inter-annual variability but no linear trends. The triggering rainfall that generates flash floods was analyzed with respect to 1–3-hourly and daily precipitation totals and circulation types from the objective classification. While flash floods can occur anywhere, they were more frequently recorded at the foots of mountain slopes, often coinciding with “critical points” where built-up areas meet concentrated surface runoff pathways. The division of material damage caused by flash floods into eight categories indicated that the highest proportion of damage was to streets and communications (24.3 %), to houses (21.7 %), and to their cellars and basements (18.3 %). There were also 36 recorded fatalities. The understanding of flash floods in the Czech Republic aligns generally well with studies of flash floods in other European regions.