Surface Morphology Damage Research Articles

A comparative study on mechanical-electrical-thermal characteristics and failure mechanism of LFP/NMC/LTO batteries under mechanical abuse

Understanding the failure behaviors and failure mechanisms of lithium-ion batteries under mechanical abuse is essential for numerical reconstruction of abuse scenarios for different types of cells. This study investigates the mechanical-electrical-thermal characteristics, components tensile properties and failure mechanisms of LiFePO4 (LFP), Li(Ni0.5Mn0.3Co0.2)O2 (NMC), and Li2TiO3 (LTO) cells through indentation experiments, including ball intrusion, cylindrical intrusion, and out-of-plane compression modes at quasi-static loading rates. Additional ball intrusion experiments were conducted at varying loading rates. This study compares the effects of different material systems on battery performance under standardized mechanical abuse conditions. Post-test examinations analyze surface damage and internal component fracture morphology. Two distinct fracture modes were observed: ductile fracture and brittle fracture. The findings suggest that, under the same loading mode, LTO cells exhibit distinct failure behavior compared to NMC and LFP cells, attributed to differing material properties and resulting fracture modes during intrusion. Based on the analysis of the tensile results of the battery components, the cell fracture mode may be related to the tensile strength of the separator. The loading rate significantly impacts the mechanical-electrical-thermal performance of pouch cells, resulting in increased cell stiffness and shorter internal short circuit duration at higher loading speeds. However, the effect of loading rate is consistent across cells with different material systems.

Micron-size bubble defects in fused silica and its laser induced damage near 355 nm

In this paper, considering micro-bubble as a factor affecting the quality of optical components assembled in high-energy laser system, the behavior of small bubble inside high-temperature fused silica is investigated by two-phase flow theory. Furthermore, the effect of microbubbles as high-energy laser damage precursor is studied in detail. It is found that if micro-cracks or voids exist in fused silica during synthesis, basically spherical bubbles could be formed and hardly released. Thereafter, light intensity enhancement effect is evaluated at the initial stage of laser-induced damage. Both single and double bubbles attribute to laser energy intensification in a specific area. The Gaussian pulsed laser near 355 nm is utilized to test laser-induced damage thresholds (LIDTs), and the LIDTs of fused silica with unreleased micro-bubbles decrease from 9.7J/cm2 to ∼7.0 J/cm2. The surface damage morphologies and laser-induced material modifications due to micro-bubble are much more disastrous than those without defects. We propose that the Gaussian laser-induced damage morphologies are partitioned into three feature zones for fused silica with unreleased bubbles. The research in this paper provides underlying guidance for ameliorating the quality of fused silica and understanding laser-induced damage.

Manufacturing of magnetron sputtering tungsten coatings and irradiation damage behavior under helium plasma exposure

Tungsten coatings with different surface morphologies and microstructures were prepared on a reduced activation ferritic/martensitic steel CLAM by DC magnetron sputtering. The sputtering power during coating deposition was varied from 30 W to 60 W in the experiments. The as-deposited tungsten coatings were subjected to He plasma at a sample temperature of ∼758 K with an ion flux of ∼3.0 × 1021 m−2 s−1, an incident ion energy of ∼20 eV, and an ion fluence of ∼5.3 × 1024 m−2. The tungsten coating deposited at the sputtering power of 40 W successfully gained a unique needle-like morphology and a uniform grain size of ∼100 nm. The coating combined well with the CLAM steel substrate. The nano-sized microstructure brings in high-density grain boundaries and provides sufficient He release channels. Therefore, this dense structure is preferred as an important sink of irradiation-induced defects and thus exhibits excellent He plasma resistance. The formation of fuzz is correlated with the He plasma fluence. Accordingly, our work focused on the investigation of the damage behavior of tungsten coatings under the variation of He plasma irradiation influence. The surface damage morphology of the W coating exhibited a surface bulge, a localized fibrous structure, and a fuzz structure when the irradiation influence was 5.0 × 1023, 2.0 × 1024, and 1.0 × 1025 m−2, respectively. Many fuzz fiber structures were generated at the He plasma fluence of up to ∼1.0 × 1025 m−2. The damage of the tungsten coating increased in severity with the ion fluence until the columnar crystal failed.

Influence of high temperature on the tribological properties of hybrid PTFE/Kevlar fabric composite

The tribological properties of PTFE/Kevlar fabric are extremely important for the service behavior of self-lubricating and maintenance-free joint bearings in aviation, aerospace and other fields that require high wear performance at different temperatures. This paper aims at investigating the influence of the ambient temperature on the tribological properties of hybrid PTFE/Kevlar fabric through reciprocating wear tests. The wear loss, surface damage morphology and tribo-chemical behaviors of PTFE/Kevlar at the temperature range of 25–200 °C are first analyzed. The wear mechanisms, damage behaviors and their transitions with the increase in the ambient temperature and reciprocating cycles are then systematically discussed. This information can provide a guide to master the range of safe use and the optimization of materials.

Rolling contact fatigue and damage characteristic of AISI 9310 steel with pre-laser shock peening treatment

Contact fatigue is one of the most common failure modes for gear tooth, which is closely associated with the material surface state. In this paper, the specimens with and without pre-LSP treatment were subjected to rolling contact fatigue (RCF). The surface damage morphology/ characteristics and fracture morphology were characterized. The results showed that RCF life was improved from 5.37 × 105 to 9.04 × 105 cycles after LSP treatment. The main reasons are the effect of the work hardening and compressive residual stress induced by LSP. A smaller Kernel Average Misorientation value with pre-LSP treatment at subsurface after RCF, resulting in the increase of plastic deformation resistance and RCF life.

Influence of the polymer matrix type on cavitation resistance of composites

Cavitation resistance of polymer matrix / basalt powder composites was determined in this work. Two types of composites were tested: epoxy resin / basalt powder composite and polyester resin / basalt powder composite. In both cases, a basalt powder was used as reinforcement in the resin (grain size 20μm, in the amount of 15 wt%). An ultrasonic vibration method with a stationary sample was used to test the cavitation resistance of composites in laboratory conditions. The change in sample mass with test time was monitored to define cavitation rate. Scanning electron microscopy was used to monitor the morphology of composites surface damage.

Surface structure evolution and Raman response for multipulse, few-cycle, laser damaged ZnSe.

Multiple 11-fs infrared, few-cycle laser pulses were applied to a polycrystal ZnSe surface to study the evolution of surface damage morphologies. The polycrystalline grain boundaries seem to be the initiation site of surface damage and formation of ripples, which evolve as the result of many laser pulses at the same site. Scanning electron microscopy and atomic force microscopy (AFM) were applied to characterize the surface. The crystalline change and material phase transition were examined by confocal Raman spectroscopy. The thermal expansion coefficient increased slightly in the ablated zone compared to the non-ablated zone according to an AFM thermal tip test. The results show the growth and organization of surface ripples and the change of thermal properties as the number of irradiations at each site increases.

Advanced damage resistance monitoring procedure on the composite materials’ surface-exposed to cavitation testing

Morphology and development of surface damage of alumina-based materials, resulting from cavitation erosion is studied in this paper. Two series of samples were prepared: samples without fibers and those with the addition of 2 wt % of ceramic fibers. The form of surface damage is considered to be the information carrier for the analysis of the resistance of materials to cavitation and the quality of this information is determined. The surface of the samples was monitored in defined time intervals in order to prepare the digitized image suitable for further analysis using image analysis software. The principal component analysis was applied to examine the appearance of certain morphological characteristics depending on the behavior of the material during cavitation erosion. It was concluded that the addition of ceramic fibers gained in importance after a long time of cavitation erosion, while during a starting period of time the difference in the morphology of the damage is not very observable.

Premazi na bazi bazalta za zaštitu metalnih konstrukcija

The paper present the results of the synthesis of a new refractory coating based on basalt for the protection of metal construction under conditions of cavitation. Initial basalt samples obtained from the locality Vrelo - Kopaonik. The basalt based refractory filler was obtained by crushing and grinding selected samples of basalt rock. XRD, SEM and optical microscopy methods were used to characterize the obtained filler samples. The research defined the composition of basalt -based coating with epoxy resinbased binder, organic additives and organic solvent. The resistance properties of protective coatings applied to metal surface were investigated using the ultrasonic vibration method with a stationary sample according to the ASTM G 32 standard. To evaluate the resistance of the sample surface to the action of cavitation, the sample surface was examined before and during testing. The surface of the samples was monitored by scanning electron microscopy in order to analyze the morphology of surface damage. Computer image analysis according to the Image Pro Plus program was applied to assess the damage to the sample surface. The obtained test results showed high resistance of the coating layers to the effect of cavitation, with small mass losses, small damage to the coating surface and a cavitation rate of 0,1 mg/min.

Određivanje otpornosti na dejstvo kavitacije uzoraka pirofilita

The resistance under the action of cavitation of sintered pyrophillite samples was investigated. The initial sample of pyrophillite from the Parsovic-BiH deposit was ground a vibrating mill to a granulation of 20 mm, pressed and sintered at temperatures (⁰C): 100; 1100; 1200. To assess cavitation resistance, the change in sample mass as a function of cavitation time was monitored. The cavitation erosion test was performed using the ultrasonic vibratory cavitation test method according to the ASTM G-32 standard. Cavitation velocites were calculated for all samples, as a basic indicator of the resistance of the material under the action of cavitation. The change in the morphology of the surface with the test time was followed by scanning electron microscopy. Based on the values of cavitation velocity and analysis of the surface damage morphology, the cavitation resistance of the tested samples based on pyrophillite was determined. The obtained results indicate that the samples of sintered pyrophillite have satisfactory resistance to the action of cavitation and be applied in conditions of lower cavitation loads.

Experimental investigation of textile structure reinforced composite leaf spring for their cyclic flexural and creep behaviour

This work dealt with the investigation of cyclic flexural strength and time dependent creep behavior of E-glass/epoxy-based different textile structure reinforced (chopped fibers, unidirectional (UD), bidirectional plain woven (2D), and 3D woven solid structures (orthogonal and Interlock) composite leaf spring. All textile structures were developed using a rigid rapier mutibeam weaving machine. Four different 3D woven orthogonal structures with varying binder percentage (3, 7, 10, and 13%) were developed to optimize weaving construction parameters for leaf spring application. The 3D orthogonal reinforced composite leaf spring exhibited improved cyclic flexural and creep performance and 3S1B stuffer-binder combination was found with the highest initial flexural strength, lowest drop in cyclic flexural strength and improved creep resistance. UD based composite leaf spring exhibited comparable properties to 3S1B based composite leaf spring. Composite leaf springs were further analyzed for their surface damage (tensile side) due to cyclic flexural loading. Structural variation (binder percentage) of 3D structure reinforced leaf spring has a significant influence on their failure (surface damage) morphology. 3D woven composite leaf spring with minimum binder tow percentage was found to be a potential material for automotive leaf spring from cyclic flexural strength, creep resistance, stiffness retention and failure morphology point of view.

Experimental and numerical study on fretting wear and fatigue of full-scale railway axles

This study investigated the fretting wear and fatigue of full-scale railway axles. Fatigue tests were conducted on full-scale railway axles, and the fretting wear and fretting fatigue in the fretted zone of the railway axles were analysed. Three-dimensional finite element models were established based on the experimental results. Then, multi-axial fatigue parameters and a linear elastic fracture mechanics-based approach were used to investigate the fretting fatigue crack initiation and propagation, respectively, in which the role of the fretting wear was taken into account. The experimental and simulated results showed that the fretted zone could be divided into zones I–III according to the surface damage morphologies. Fretting wear alleviated the stress concentration near the wheel seat edge and resulted in a new stress concentration near the worn/unworn boundary in zone II, which greatly promoted the fretting crack initiation at the inner side of the fretted zone. Meanwhile, the stress concentration also increased the equivalent stress intensity factor range ΔKeq below the mating surface, and thus promoted the propagation of fretting fatigue crack. Based on these findings, the effect of the stress redistribution resulting from fretting wear is suggested to be taken into account when evaluating the fretting fatigue in railway axles.

Dry Rolling/Sliding Wear of Bainitic Rail Steels under Different Contact Stresses and Slip Ratios.

This study aims to deeply understand the effect of contact stress and slip ratio on wear performances of bainitic rail steels. The results showed that the wear loss increased as the contact stress and slip ratio increased. Based on the surface damage morphology and microstructural analyses, it revealed that the rolling contact fatigue wear mechanism played a significant role under the low slip ratio, but the dominant wear mechanism transferred to the abrasive wear at the high slip ratio. Meanwhile, the bainitic steel specifically presented worse wear resistance under the abrasive wear mode. Compared with the influence of a slip ratio, the increase in contact stress led to severer plastic flows and contributed to the propagation of cracks. In addition, the contact stress and slip ratio had the opposite effect on the friction coefficient, that is, the friction coefficient of bainitic steels behaved the inverse proportion with the contact stress, but positive proportion with the slip ratio. At last, the increase in slip ratio had more significant effect on the reduction of retained austenite (RA) than the enlargement of contact stress due to the fact that the RA would probably be removed before the martensitic transformation occurred under the abrasive wear mechanism.

Role of microstructure in plastic deformation and crack propagation behaviour of an α/β titanium alloy

The deformation and crack propagation behaviour have been comparatively investigated in a titanium alloy with bimodal microstructure (BM) and bilamellar microstructure (BLM). The results show that higher fracture toughness (58 MPa m1/2) was obtained for the BLM than that BM one (45 MPa m1/2). The deformed microstructure, crack initiation and propagation and surface damage morphology were observed by SEM and EBSD. Fatal cracks easily nucleated at the larger primary α phase, especially at the equiaxed αe/β interface and primary α lath (αl), and often grow along a straight line, which accelerated the crack propagation and leaded to non tortuous crack path in BM. For the BLM, slip hardly transferred the αl/βtrans interface due to the secondary α(αs) precipitation in the β lamellas. Cracks initiated at the boundaries of α colony and propagated with a zig-zag way, which leaded to a high branch and fluctuation of the crack of BLM and generated a relatively superior fracture toughness performance. These results indicate that a small amount of αl colony surrounded with βtrans matrix is beneficial to the improvement of fracture toughness, which can provide a good theoretical support to tailor the microstructure and mechanical performance of titanium alloys.

Surface analysis of retrieved bilateral UHMWPE tibial inserts under varus malalignment condition

Failure analysis on a retrieved ultra-high molecular weight (UHMWPE) knee tibial inserts of bilateral total knee replacement (TKR) was performed due to aseptic loosening detected after 16 years (left) and 12 years (right) in vivo services. Despite long implantation time, the effect of varus malalignment present on a 71 years old female patient (body mass index, 35.1) with a non-active lifestyle will be considered as a factor towards the TKR failure. We, therefore, determined whether implant malalignment was associated with increased surface damages in both retrieved tibial inserts. Surface damage morphology was assessed using a 3D laser microscope and Scanning Electron Microscope (SEM). ATR-Fourier Transform Infra-Red (ATR-FTIR), Differential Scanning Calorimetry (DSC) and Gel-Permeation Chromatography (GPC) were used to measure changes of chemical and physical properties of retrieved inserts. Results show left-16 years insert possesses more severe wear degradation (crater and cracks) compare to wear on right-12 years insert (delamination, multidirectional scratches, and ripple). The surface roughness on the medial compartment seems to be higher than the lateral side for both inserts which can be affected by uneven load distribution contribute by the varus deformity. Higher crystallinity of left-16 years insert (66.99%) compare to right-12 years insert (56.52%) were an indicator of major mechanical changes happen on left insert which was contributed by oxidation with respect to implantation time of both inserts. Our findings revealed that in vivo oxidation is a main contributing factor to the failure of implants, but not varus malalignment. The material properties in the oxidized layer are significantly altered, including a very substantial reduction in molecular weight displayed by both inserts.

High-velocity impact behaviors and post-impact tension performance of 2D-C/SiC composite beams

2D-C/SiC composites have widely been used in aeronautical and aerospace engineering, but their mechanical behaviors under small-mass and high-speed impact have not been thoroughly studied yet. In this paper, 2D-C/SiC beam specimens were impacted by a single-stage light-gas gun and the fracture processes were captured by a high-speed camera. Post-impact internal and surface damage morphologies were scanned by a CT and a SEM, respectively. Similar damage modes were revealed by high-speed images. Subsequently, quasi-static post-impact tension tests were conducted to understand the residual mechanical properties. Acoustic emission (AE) signals of specimens were detected during the tests and then classified by the K-means algorithm. Therefore, evolutions of matrix damage, interfacial delamination and fiber fracture were recognized. At the same time, strain value was obtained by digital image correlation (DIC) method and main crack propagations were obvious in strain contours. A combination of the AE and DIC methods very well monitored the real-time damage during post-impact testing, which further revealed the damage during impact phase.

The Tribo-Fatigue Damage Transition and Mapping for Wheel Material under Rolling-Sliding Contact Condition.

The purpose of this work is to construct a tribo-fatigue damage map of high-speed railway wheel material under different tangential forces and contact pressure conditions through JD-1 testing equipment. The results indicate that the wear rate of the wheel material varies with tangential force and contact pressure. The wear mapping of the wheel material is constructed and divided into three regions: slight wear, severe wear, and destructive wear, based on the wear rate under each test condition. With an increase in tangential force and contact pressure, the maximum crack length and average crack length of the wheel material increases. According to the surface damage morphologies and corresponding statistical results of average crack length of wheel material under each experiment condition, a tribo-fatigue damage map is constructed and divided into three regions: slight fatigue damage region, fatigue damage region, and severe fatigue damage region. Fatigue cracks initiate on the wheel specimen surface. Some cracks may propagate into material and fracture under cyclic rolling contact; some cracks may grow into inner material with a certain depth, and then turn toward the surface to form material flaking; some cracks may always propagate parallel to the wheel roller surface.

Concentric ring damage on the front surface of fused silica induced by a nanosecond laser

Concentric rings are observed on the front surface when a laser pulse focuses on the rear surface of fused silica. The spatial distribution of concentric rings presents a certain regularity, and the width and depth of the ring gradually increase from inside to outside. These features of the concentric rings are affected by the laser wavelength and energy. Their formation mechanism is explored by means of combining a time-resolved pump-probe shadowgraph and surface damage morphology. Concentric rings are formed during the irradiation process of one nanosecond pulses, whose radius and depth characteristics may record the relationship between the early stage of laser-induced damage structure and the evolution of early plasma.

Improved cyclic softening behavior of ultrafine-grained Cu with high microstructural stability

We report that the uniform and stable microstructure essentially ameliorate the cyclic softening of the ultrafine-grained (UFG) Cu prepared by friction stir processing (FSP) and then enhance its low-cycle fatigue properties. In lieu of the fatigue-induced grain coarsening, dislocation and grain boundary (GB) activities play crucial roles in accommodating the cyclic plasticity. In addition, the protrusion and small cracks near the GB regions rather than shear bands are main surface damage morphologies that lead to its final fatigue failure.

Comparative study of crack growth behaviors of fully-lamellar and bi-lamellar Ti-6Al-3Nb-2Zr-1Mo alloy

The fatigue crack growth (FCG) behaviors of fully-lamellar and bi-lamellar Ti-6Al-3Nb-2Zr-1Mo alloy were investigated comparably. The FCG rate of bi-lamellar structure is lower than that of fully-lamellar structure, especially at the low stress intensity factor range (ΔK < 40 MPa m1/2). The fatigue crack growth path, deformed sub-structure and surface damage morphology were observed by SEM and TEM. For the fully-lamellar structure, because the same orientation of α lamellae and Burgers relationship between α and β lamellas in the α colony, the fatigue cracks often grow along a straight line in the α colony by cutting the β lamellas. For the bi-lamellar structure, because the resistance of secondary α (αs) precipitations in the β lamellas to dislocation slips, the frequency of crack propagation along the α/β interface increases. The fatigue cracks often grow along a zigzag in the α colony, which results in the fatigue crack growth path is more circuitous than that of the fully-lamellar structure in α colonies, and this is the main reason that the FCG rate of bi-lamellar structure is lower than that of fully-lamellar structure. This research has an important engineering significance to improve the low cycle fatigue (LCF) performance of the coarse lamellar structured Ti alloys.