Damage Characteristics Research Articles

Evolution and Characterization of Uniaxial Compression Damage of Coal Measure Rock

In order to study the evolution law of uniaxial compression damage and its characterization method, three kinds of rocks with different lithology that commonly exist in coal measure rock were taken as the research objects to explore the relationship between their mineral composition, microstructure and mechanical properties, and the feasibility of acoustic emission (AE) characteristic parameters and AE spatial location to characterize the evolution process of uniaxial compression damage of rocks was compared and analyzed. A damage constitutive model based on AE cumulative ringing count was established and verified by numerical simulation. The results show that the differences in the micromorphology and mineral composition of coal measures with different lithology directly affect their physical and mechanical properties and load damage characteristics. AE characteristic ringing count can effectively represent the damage evolution process of rock during loading. Based on rock porosity characteristics and AE cumulative ringing count during loading, a constitutive model considering initial damage and cumulative damage was established. The theoretical analysis results of the damage constitutive model are in good agreement with the results of laboratory experiments and numerical simulation, which can be used to analyze the damage process of coal measure rock under load.

Impact response of 3D printed cornstalk-inspired structures: The effect of indenter shape on penetration

This paper reports the mechanical response and damage tolerance of 3D-printed cornstalk-inspired structures subjected to impact loading. Specimens were subjected to dynamic indentation tests at multiple impact energies with flat, hemispherical, and conical indenters. The mechanical properties of the base material (ABS) were measured across varying strain rates using a Shimadzu® Universal Testing Machine and a Split Hopkinson Pressure Bar. The effect of geometrical variations of the constituents on energy-absorbing capability was also investigated. Damage characteristics were interrogated through X-ray CT scans and provided detailed failure modes associated with each indenter shapes. Further, finite element simulations provided insights into the penetration mechanisms associated with the different indenter shapes. The results demonstrated that test specimens impacted by flat indenters absorbed ∼25 % less energy than those impacted by hemispherical and conical indenters. Among the various indenters, the conical shape had the highest duration of contact force within the specimen before experiencing failure by matrix cracking and complete perforation.

Post-disaster investigations of damage feature of buildings and structures due to several local strong winds in China during 2021–2024

Local strong winds such as tornadoes and downbursts are rare in terms of measured wind speed data due to their rapid formation and strong destructive power. Post-disaster investigations have become an important approach for rating the strength of these two kind of winds and analyzing structural failure mechanism. From 2021 to 2024, several tornadoes and downbursts occurred in China. This study delineated changes in the intensity levels of wind disasters along their paths based on on-site disaster investigations and established standards for the level of structural damage based on the extent of functional loss and repair. This study focused on the damage feature to light steel structures, masonry structures, steel-concrete structures, and pole structures, and discussed the causes of the damage from the perspectives of construction and force transmission mechanisms. In addition, this study estimated the equivalent wind speeds based on the damage feature of pole structures and metal roof claddings. To reproduce the damage process for a group of high-rise buildings, the computational fluid dynamic (CFD) technology is used to simulate the airflow distribution inside buildings under two conditions of open and closed interior doors. The investigation results can provide useful information for the wind intensity classification and rating standards in China. Meanwhile, compared with the interior doors being open or closed, closing indoor doors during strong winds can significantly reduce indoor wind speeds, which is beneficial for ensuring safety.

Damage and Crack Propagation Mechanism of Q345 Specimen Based on Peridynamics with Temperature and Bolt Holes

With the increasing demand for the performance and design refinement of steel structures (including houses, bridges, and infrastructure), many structures have adopted ultimate bearing capacity in service. The design service lives of steel building structures are generally more than 50 years, and most of them contain bolted connections, which suffer from extreme conditions such as fire (high temperature) during service. When the structure contains defects or cracks and bolt holes, it is easy to produce stress concentration at the defect location, which leads to crack nucleation and crack propagation, reduces the bearing capacity of the structure, and causes the collapse of the structure and causes disasters. In the process of structural damage and crack propagation, the traditional method has some disadvantages, such as stress singularity, the mesh needing to be redivided, and the crack being restricted to mesh; however, the integral method of peridynamics (PD) can completely avoid these problems. Therefore, in this paper, the constitutive equation of PD in high temperature is derived according to the variation law of steel material properties when changed by temperature increase and peridynamics parameters; the damage and crack expansion characteristics of Q345 steel specimens with bolt holes and a central double-crack at 20 °C, 200 °C, 400 °C, and 600 °C were analyzed to clarify the structural damage and failure mechanism. This study is helpful for providing theoretical support for the design of high-temperature steel structures, improving the stability of the structure, and ensuring the bearing capacity of the structure and the safety of people’s lives and property.

Damage characterization and modelling of FRP laminated composites subjected to external edge-on impact

This paper presents both experimental and numerical investigations into the edge-on impact behavior of T700/YPH307 composite laminates with varying lay-up designs and impact energy levels. Various non-destructive testing techniques, including visual inspection, ultrasonic C-scanning and X-ray computed tomography (CT), were used to detect the post-impact damage status and further reveal its 3D spatial distribution. A continuum damage mechanics (CDM) model, incorporating in-plane shear nonlinearity, fracture plane angle within anisotropic materials, as well as fiber kinking failure in longitudinal compression, was established using an explicit solver. Detailed comparison of the experimental and numerical results was conducted in mechanical response curves and failure mechanisms, where a good agreement was observed. Parameter analyses on the in-situ strengths and the friction coefficient were also performed, offering guidelines for the edge-on impact modelling. Failure mechanisms induced by edge-on impact typically exhibit two distinct features: a highly localized debris wedge, which can be regarded as a trigger in the subsequent occurrence of damage, and the bending fracture of the outer plies resulting from the wedge effect during the oscillating stage of an impact force plateau. Besides, higher impact energy exacerbated internal damage, while the influence of the lay-ups was relatively limited.

To Evaluate The Histomorphological Changes Of Postmortem Transthoracic Needle Biopsy/Autopsy Lung In COVID-19 Patients

Objective: To study the histomorphological changes in postmortem needle biopsy/autopsy lung in COVID-19 Patients. Study Design: This was an observational study done at Shri Atal Bihari Vajpayee Medical College & Research Institute, Bengaluru, and Karnataka from March 2021 to May 2021. Methodology: A total of 30 patients who died of Covid-19 were included and all of them were diagnosed to be Covid -19 positive by RT-PCR testing. Post-mortem transthoracic needle biopsy was done to obtain lung tissue by using B-Bard biopsy gun in midaxillary approach. The biopsy samples were grossed and processed after fixing for 48hrs. The slides obtained were stained by routine hematoxylin and eosin stain, studied for morphology of the lung tissue and findings were recorded. Results: We obtained consent for post-mortem transthoracic needle biopsy/autopsy of lung in 30 deceased cases. All these cases were positive for SARS –COV2 on RT-PCR. The age of the cases was ranging from 26-72 years and median age is 53years, males (63.3%) were affected more than females (36.7%). Most deceased had comorbidities, among them diabetes mellitus (26.6%) and hypertension (26.6%) were most common. Lung biopsy samples were taken from 30 deceased patients. Histomorphological feature of diffuse alveolar damage was seen in 90% (27 out of 30) cases. Other findings noted on microscopy were chronic interstitial inflammation in 6.7% cases, pulmonary edema (3.33%), intra alveolar haemorrhage (3.33%) and viral cytopathic changes (3.33%). Conclusion: This study highlighted the pulmonary morphological changes which are most prominent in COVID-19 infections, but it was a difficult to ascertain that the findings are related to viral infection or due to associated coomorbidities

Assessing social equity of federal disaster aid distribution: A nationwide analysis.

In this study, we conduct the first comprehensive, nationwide assessment of social equity performance of multiple federal post- and pre-disaster assistance programs that differ in targeted recipients, project types, forms of aid, and funding requirements. We draw on the social equity and distributive justice theory to develop and test a set of hypotheses on the influence of program design and specificity on their aid distributional patterns and equity performance. The analysis uses panel data of about 3000 US counties to examine the relationship between a county's receipt of federal assistance and its recent disaster damage, socioeconomic, demographic, political, local government, and geographic characteristics in a two-stage random effects Tobit model. Expectedly, we find that post-disaster grants are largely driven by recent disaster damage, while damage is simultaneously influenced by local socioeconomic conditions. For all disaster programs, disproportionately more federal aid is allocated to populous counties. For programs geared toward state and local governments and targeting community recovery and mitigation, more aid is received by counties with better socioeconomic conditions. Conversely, for programs targeting individual relief and recovery, more aid is given to counties with lower incomes and greater social vulnerability. Results also indicate that counties located in high-risk regions receive greater outlays. These findings shed light on the varying degrees of social equity of federal disaster assistance programs tied to their cost-share requirement, funding caps, and inherent complexity of application procedures.

Fatigue-thermal damage characteristics of red sandstone with a hole under high-temperature cyclic loading coupling and microstructural degradation

In underground coal gasification (UCG) projects, deeply buried subterranean projects are significantly influenced by high temperatures, alongside disruptive loads such as excavation, blasting, and drilling. Therefore, it is essential to study the fatigue behaviors of rocks under the coupled effects of thermal elevation and cyclic loads. This study performed uniaxial compression and cyclic loading-unloading tests on red sandstone specimens with cavities. The high-temperature fatigue behaviors of specimens were explored from various aspects, encompassing stress, deformation, energy, damage, and the microstructural variations of the specimens after high-temperature procedures were assessed by utilizing scanning electron microscopy (SEM). At temperatures below 600 °C, SEM images indicate a contraction of microcracks in the specimens, whereas temperatures above this threshold lead to their expansion. Notably, the total, elastic, and dissipated energy density of the specimens exhibit a curve of second degree with the upper limit stress. Additionally, elastic and dissipated energy densities linearly correlate with input energy density. Furthermore, the coupled damage and axial strain of the specimens positively correlate with the temperature. The damage mode of thermal fatigue is attributed to the accumulation and penetration of transgranular fractures within the red sandstone.

Damage evolution and acoustic emission characteristics of sandstone under different true triaxial cyclic loading and unloading modes

In the process of deep coal mining, the cyclic mining disturbance behavior produces significant cyclic loading and unloading effects, to ensure safe production in the mining area, it is necessary to study the damage characteristics and acoustic emission characteristics of the rock body under different cyclic loading and unloading effects. This study developed a TAWZ-5000/3000 rock true triaxial (disturbance) test system and used it to carry out true triaxial cyclic loading and unloading tests in different modes, with acoustic emission (AE) monitoring of the deformation and damage processes. The test results proved that a large number of cycles weakens the rock’s ability to control deformation, and this weakening ability is also related to the types of cyclic loading and unloading modes. The hysteresis loop characteristics and mechanical parameters show obvious path dependence. Based on the damage equivalence method, it is found that the absolute damage parameter increases with the increase of the number of cycles in the same mode, and the accumulation rate of the cumulative damage parameter is faster; the cumulative damage parameter in the equal amplitude cyclic loading and unloading (EAC) mode is always higher than that in the other two modes. The normalized AE ring count rate in the rock samples under cyclic loading and unloading has a significant relationship with the damage percentage, and the crack extension scale function (b-value) shows the “steady increase – strong fluctuation − significant decline” trend. By analyzing the AE characteristic parameters, namely rise time/amplitude (RA) and ringing count/duration (AF), it is found that the sandstones in EAC, graded cyclic loading and unloading (GC), and stepped cyclic loading and unloading (SC) modes are mainly damaged by tension-shear and shear, respectively. By analyzing the values of the acoustic emission parameters RA-AF, it is found that the sandstone is mainly damaged by tensile shear, tensile tension, and shear under EAC, GC, and SC modes, respectively, corresponding to the rock samples’ damage patterns. The study results have important guiding significance for preventing and controlling disasters in deep mines.

A deep learning-based spatial gradient reconstruction method for efficient damage identification in composite with high-sparsity Lamb wavefield

The structural integrity and safety of carbon fiber reinforced plastics (CFRP) are vulnerable to delamination, which is often imperceptible to the naked eye. Although the Scanning Laser Doppler Vibrometer (SLDV) has shown promise in damage quantification of CFRP, its time-consuming measurement process limits its application in engineering scenarios. To address this, we introduce a novel damage index, the spatial gradient, which captures the interaction between delamination and the wavefield. We have also developed a neural network capable of reconstructing the spatial gradient directly from high-sparsity Lamb wavefield data obtained at an extremely low spatial sampling rate, thereby significantly reducing measurement time. To enhance the network’s capability to detect wavefield anomalies, we employ the cross-attention technique, allowing for the direct injection of shallow features representing local wavefield distortions caused by damage into the decoder. Additionally, we integrate multiple reconstruction layers to guide the wavefield reconstruction process, ensuring meaningful information is captured at each stage. Our method achieves substantial improvements in reconstruction accuracy, increasing from 70 % to 92 % in single-damage scenario and from 14 % to 72 % in multi-damage scenario compared to the previous state-of-the-art techniques. By using the reconstructed spatial gradient field for damage imaging through spatial covariance analysis, our approach demonstrates its feasibility and generalizability across various damage locations. This suggests its potential as a reliable solution for fast and accurate damage characterization, reducing the measurement burden and enhancing practical applicability.

Pore water pressure dynamic response in asphalt mixture: A measurement system development

The pore water pressure dynamic response in asphalt pavements is complex and distinct, which is closely related to pavement damage and seepage characteristics. However, existing measurement methods often don’t simulate the dynamic pore water pressure realistically and combine with measuring position and pavement saturation adequately. This study develops a system to measure pore water pressure in asphalt mixtures under dynamic loading. It simultaneously considers vehicle-pavement interactions, sensors embedding and pavement saturation. The test results shows that the output equivalent loads accuracy of the system reaches 80 % and higher. The noise interference from air is identified, and the FFT digital filters are designed to minimize it. The application result shows pore water pressure response varies under different loading modes. The pressure rapidly rises, peaks, then diminishes to 0 under intermittent loading, while it rebounds after decreasing but never reaches 0 under continuous loading. A turning point at 9.8 % void ratio is noted, where denser mixtures exhibit more hysteresis and longer dissipation times, suggesting increased resistance to water transfer.

Effect of human reovirus strain R-92 on tumor cell lines

Background. Among all the new methods and approaches, virotherapy with oncolytic viruses, both in combination with immunotherapy and without it, shows high efficiency in various phases of clinical trials and good tolerance by patients.Aim. To study the sensitivity of some immortalized cancer cell lines to the R-92 strain of human reovirus with cell characteristics at the ultrastructural level.Materials and methods. The study was carried out on cell lines of HeLa, A549, U87MG. Cells were planted in an amount of 15 thousand per well of a 96-well plate and after adhesion, the virus was inoculated by adding a medium containing virus particles in 4 tenfold dilutions (approximately 10 9 –106 particles per ml). Next, the cells were cultured for 24 h, after which the number of living cells in the wells was determined indirectly using the methyl tetrazolium test, which was carried out according to standard methods. To study the ultrastructure of infected cells, cells were seeded into a T25 flask and inoculated with the virus at the maximum concentration. After 24 h of cultivation, the cells were fixed in a 2.5 % glutaraldehyde solution in phosphate buffer for 1 h, after which they were washed three times in phosphate buffer and samples were processed for TEM according to standard methods.Results. Diluting the virus 1000 times led to a decrease in the cytostatic effect in all three cultures to a level practically no different from the control. HeLa turned out to be the most sensitive culture to reovirus. In the experiment, the number of living cells decreased to 60.4 ± 10.2 % compared to the control during incubation with the maximum number of viral particles and to 63.7 ± 16.2 % with a tenfold dilution of the virus. This indicator was significantly lower than in the other two studied cultures under these cultivation conditions (p <0.001).In addition, at the maximum virus concentration, the A549 culture was less sensitive than the U87MG culture (p <0.01). At lower concentrations of viral particles, the average viability of the studied cell lines did not differ significantly from each other. Analysis of electron diffraction patterns showed that the virus successfully replicates in the cytoplasm of the studied cultures, but is not released from the cell, which is apparently due to the short incubation period. TEM also showed cell damage characteristic of apoptosis or necroptosis, uniformly expressed in all studied cultures.Conclusion. Cell lines A549, HeLa and U87MG, according to the results of the methyl tetrazolium test, demonstrate different sensitivity to the human reovirus strain P-92. The TEM picture of cells from infected cultures showed signs of the development of apoptosis or necroptosis.

A Hardware Circuit for Extracting Weak Damage Characteristics of Steel Wire Rope Using an Asymmetric Monostable System

ABSTRACTNon‐destructive testing of steel wire rope is significant in lifting machinery. However, it is still challenging to extract weak damage characteristics of steel wire rope under noise caused by harsh working conditions. Currently, extracting damage characteristics mostly involves secondary processing through software, which is cumbersome and inefficient. Stochastic resonance is a typical stochastic dynamic phenomenon of a nonlinear system, and it can extract weak damage characteristics through the cooperation of noise, weak signals, and nonlinear system models. Among different nonlinear system models, the asymmetric monostable system, which has only one fixed point, is advantageous for achieving a more stable response under pulse excitation. In this work, a hardware circuit based on an asymmetric monostable system is constructed to extract weak damage characteristics of steel wire rope. This hardware circuit can efficiently extract damage characteristics without secondary processing. Additionally, the denoising performance of the nonlinear circuit, focusing on weak signals with damage characteristics under a noisy background, is evaluated using the cross‐correlation coefficient and local cross‐correlation coefficient. The results demonstrate that the proposed method provides high recovery in the non‐destructive testing of steel wire rope.

Critical damage events of 3D printed AlSi10Mg alloy via in situ synchrotron X-ray tomography

Fish-scale-like melt pool structures and internal defects are unique characteristic in additively manufactured (AM) metals. These features play a critical role in the damage and fracture processes under different service conditions, governing the material's performance. However, the relationship between these damage features and loading conditions, as well as the spatial interactions between melt pool structures and internal defects remains incompletely understood. By in situ time-lapse synchrotron X-ray tomography and diffraction, we identify the initiation and growth events of life-limiting damage under tensile, low cycle fatigue (LCF), and high cycle fatigue (HCF) loading. A novel transition from meso-structure insensitive, defect-dominated short fatigue crack propagation to a meso-structure sensitive mechanism occurs as the plastic zone expands of a growing crack. Under tension and LCF, the damage accumulation gradually increases and micro-voids nucleate at the melt pool boundaries (MPBs) after which the crack path follows the MPBs. In contrast, under HCF, surface defects initiate fatigue cracking and the MPBs have a very limited effect on the crack propagation path. Finally, physics-informed machine learning method is introduced to develop a novel methodology for predicting fatigue life by including three-dimensional features of defects in AM parts.

Effect of time of harvesting and post-harvest treatments on physical characteristics of sap burn damage of mango (Mangifera indica L.) cv. Dashehari in Telangana state

Effect of time of harvesting and post-harvest treatments on physical characteristics of sap burn damage of mango (Mangifera indica L.) cv. Dashehari in Telangana state

Heat transfer-deformation characteristics and fracture damage analysis during LN2 freeze-thaw process in different rank coals

Exploring the heat transfer and deformation characteristics of coal bodies of different coal ranks during the freeze-thaw process is of significant importance for analyzing the fracture mechanism under the effect of liquid nitrogen (LN2). This experiment targets lignite, bituminite, and anthracite under both saturated and dry conditions. A real-time temperature-strain monitoring system was employed to observe the heat transfer and deformation characteristics of coal samples with different ranks throughout the freeze-thaw cycle. Additionally, a nuclear magnetic resonance system was utilized to examine the characteristics of pore damage before and after fracturing. The findings reveal: (1) During the freeze-thaw process, the absolute value of the temperature evolution rate for dry coal samples shows a negative correlation with coal rank, indicating a close link between temperature diffusion and intrinsic coal properties like oxygen content and porosity. (2) For saturated coal samples, the absolute value of the temperature change rate during freezing decreases as the coal rank increases, with the opposite trend observed during thawing. The phase change effect of water in fractures during freezing can enhance internal temperature diffusion in the coal body, while it acts as an inhibitor during thawing. (3) Based on the trend of strain fluctuations, the coal body deformation process during the freeze-thaw cycle can be segmented into seven stages, summarizing the general mechanisms of deformation failure. (4) Under saturated conditions, the amplitude of elastic deformation for each sample is negatively correlated with coal rank, with the sequence for dry coal samples being bituminite > anthracite > lignite. (5) The formation of a sealed space at the beginning of freezing is identified as a necessary condition for deformation during the freeze-thaw process, with the formation and strength of the sealed space depending on the temperature diffusion rate, moisture content, and inherent properties of the coal sample.

Development of a Semi-Autonomous Pulse and Receive Concrete Inspection System

Concrete structures are being subjected to increasing loads and used beyond their intended lifespan. When combined with operators shrinking maintenance budgets it is imperative structures are monitored for damage. Acoustic Emission (AE) and AE Tomography offer a method for damage detection and characterisation. However, they are encumbered by their equipment and setup requirements, and best used on areas where damage is already known to have occurred. An autonomous pulse catch system could be used to identify these areas. To explore the potential of such a system, seven concrete beams differentiated by their aggregate size were tested using an automated pulse and receive system. The effect of aggregate size, and pulse frequency on attenuation and wavespeed are investigated. The pulse regime consisted of narrowband pulses ranging from 30 kHz to 500 kHz. The results show that high frequency pulses experienced greater attenuation than low frequency pulses. Whilst a link appears between the size of the aggregate and the rate of attenuation of high frequency signals. A strong negative correlation between amplitude loss and pulse frequency was observed. For the specimen containing coarse aggregate, pulse velocity was constant between 100 kHz and 500 kHz, whereas specimens containing coarse aggregate experienced frequency dependant attenuation. This testing shows the significant potential for an automated pulse and receive system, which could lead to the development of an autonomous health monitoring system. In addition, the approach can be instrumental in developing large data sets, that can be used in Machine Learning processes, to develop a deeper understanding of AE signal propagation in concrete materials.

Interference effect of frequency selective surface on lightning attachment

Airborne electromagnetic functional devices represented by frequency selective surface (FSS) are receiving increasing attention due to the ever-growing complication of electromagnetic environment in air space. Previous investigations have highlighted the capability of FSS to induce the distorted electric field encompassing an airborne radome. This phenomenon interferes with lightning attachment behavior and compromises the effectiveness of anti-lightning devices. A current challenge is how to reveal the physical mechanism behind this interference. In this paper, a lightning model is established for a honeycomb sandwich composite-FSS structure and a single FSS array, respectively, to investigate the interference effect of FSS on lightning attachment. Arc behavior is verified by structural damage characteristics in relevant experiments. An equivalent circuit representing the process of an FSS array suffering a lightning strike is proposed to reveal the interference mechanism of FSS. The results indicate that the electrical connectivity of FSS has a significant impact on lightning attachment behavior. Patch FSS can induce partial discharge and exacerbate interface damage to a radome while aperture FSS eases energy accumulation, although the latter is prone to induce lightning leaders without integration with composites. The obtained results provide potential guidance for the structural and anti-lightning design of an airborne radome.

First-principles investigation on the structural, optical, and laser-induced damage characteristics of boron impurity and boron-oxygen defect cluster in potassium dihydrogen phosphate crystals

The DFT+U method combined with HSE06 hybrid functional and finite-size correction has been employed to investigate the defect formation energies, lattice modifications and optical spectra of Potassium Dihydrogen Phosphate (KDP) crystals with Boron. The B defects contain the B interstitials (Bi), the B substituted P sites (BP), and the boron-oxygen defect clusters ([BP+VO]). The results demonstrate that these B defects can trigger lattice distortions. The BP and [BP+VO] have a minor lattice change rate and greater stability, while Bi has a relatively large local distortion inducing crystal damage. We have also utilized conformational coordinate diagrams to explore the optical absorption/emission processes arising from B defects. The BP and [BP+VO] were found to generate absorption peaks at 330 nm and 255 nm, while the Bi leads to absorption peaks near the absorption edge. The absorption peaks within the near-ultraviolet range might have an energy buildup at the defects, which would decrease laser utilization and harm the crystal.

Development of Johnson-Cook-Distinct Lattice Spring Model and its application in projectile penetration into metal targets

Projectile penetration into metal targets plays an important role in modern protective structure engineering, damage assessment in terrorist attacks, and car clash accident analysis, etc. The penetration process of metal target has been characterized by large deformation, high temperature, high pressure, and dynamic damage, which can be classified as a continuous-discontinuous dynamical process. To capture the dynamic responses of metal materials subjected to high-speed penetration, Johnson-Cook model has been implemented in a continuum-discrete model, namely, Distinct Lattice Spring Model (DLSM). This is achieved by redefining the constitutive model in DLSM, with plasticity hardening (plastic strain effects), strain rate, temperature, damage evolution, equation of state, etc., being taken into account, thus developing a new numerical model called JC-DLSM model. This model is validated through studying Taylor rod high-speed impact experiments, thin metal plate penetration experiments, and projectile impact experiments on titanium alloy targets. Good agreement between numerical modelling and experimental data has been achieved for all cases considered, thereby demonstrating the capability of JC-DLSM to reproduce the damage characteristics and ballistic limits of metals under high-speed impact/penetration. Then, the impacts of projectile shape, metal target surface configuration on the characteristics of penetration damage patterns have been investigated. This contributes to a better understanding of the damage mechanisms of metal targets upon penetration or impact, facilitating the computational means for analysing and optimizing the penetration resistance of protective engineering structures.