Erosion Depth Research Articles

Effect of Achieving Sustained SDAI Remission on Erosion Healing in Early Rheumatoid Arthritis - A One-year Prospective HR-pQCT Study

Background Rheumatoid arthritis (RA) is a chronic inflammatory disease with progressive joint destruction. High-resolution peripheral quantitative CT (HR-pQCT) is a novel technique for detailed bone microstructure analysis allowing volumetric assessment of bone erosions. While most patients demonstrating little baseline joint damage on radiography in the early stage of RA, whether achieving simple disease activity index (SDAI) remission can lead to better structural outcome is to be confirmed. Methods Patients with ERA were recruited and treated to the target of simple disease activity index (SDAI) remission using a standardized algorithm. One hundred patients who received the one-year tight-control treatment were grouped by achieving SDAI sustained LDA [SDAI [Formula: see text] at 6, 9 and 12 months (sLDA group) or not (non-sLDA group). HR-pQCT of the second to fourth metacarpophalangeal joints were performed at baseline, month 6 and one-year. Erosion volume and marginal bone mineral density (BMD) were measured. On an individual patient basis, erosion progression was defined as at least one erosion showing (1) an increase in erosion volume exceeding the smallest detectable change [SDC] (0.08 mm 3) AND (2) a decrease in marginal BMD exceeding SDC (7.8 mmHA/cm 3). Erosion healing was defined as at least one erosion showing (1) a reduction in erosion volume greater than SDC AND an increase in BMD exceeding SDC OR complete disappearance of the lesion AND (2) the absence of any erosion progression. Results Fourteen patients (12.8%) achieved sustained SDAI remission from 6-12 months (SDI group). After 12 months, a significant reduction in erosion volume and marginal osteosclerosis was observed in both groups. The SDI group showed a lower incidence of erosion progression (increase in volume [Formula: see text]0.08mm 3 and decrease in marginal osteosclerosis [Formula: see text]7.8mg HA/cm 3 : 0% vs 16%, p=0.135) and exhibited a higher rate of erosion healing (56% vs 29%, p=0.083) compared with the non-SDI group. In the GEE model, patients in the SDI group showed a higher likelihood of erosion healing (OR: 2.976, 95% CI: 1.0 - 8.9, p=0.050). The changes in erosion depth and width were similar between two groups. Conclusion Achieving sustained SDAI remission could improve erosion healing and limit erosion progression in patients with ERA.

Hillslope and vegetation response to postglacial warming at Bear Meadows Bog, Pennsylvania, USA

AbstractConnecting changes in erosion and vegetation is necessary for predicting topographic and ecologic change in thawing permafrost landscapes. Formerly periglacial landscapes serve as potential analogs for understanding modern permafrost landscape change, yet compared to paleoenvironmental records at these sites, less is known about concurrent geomorphic processes, particularly their rates and relationships to climate change. Here, we target sediments preserved in a central Appalachian peat bog to reconstruct sedimentation across the last deglacial warming. We use ground-penetrating radar and geochemistry of cored bog sediments to quantify sedimentation timing, style, and provenance. Using 14C dating of sedimentary and geochemical shifts, we connect depositional changes to global climate and local vegetation change. We show that deglacial warming promoted deep soil disturbances via solifluction at ca. 14 ka. In contrast, relatively wetter conditions from ca. 10–9 ka promoted shallow disturbance of hillslopes via slopewash, which corresponds to a time of vegetation change. Our results highlight climate-modulated erosion depth and processes in periglacial and post-periglacial landscapes. The existence of similar erosion and vegetation records preserved regionally implies these dynamics were pervasive across unglaciated Appalachian highlands, aiding in reconstructing erosion responses to warming at a resolution with implications for predicting high-latitude landscape responses to disturbance.

Bank erosion under the impacts of hydraulic erosion, river stage change and revetment protection in the Middle Yangtze River

Bank failures in alluvial rivers are a typical soil-water interaction problem, which is related to many factors including the direct action of flow, river stage change, and human actions (such as bank revetment). To investigate the failure mechanism of protected riverbanks and possible factors affecting their stability, we analyzed data measured from a typical reach of the Middle Yangtze River. Furthermore, we performed numerical simulations of seepage and stress variation inside the riverbank. The field observation and simulated results indicated that: (1) Hydraulic erosion by near-bank flow remains the primary factor influencing the erosion of the protected riverbank. However, the bank protection works effectively limit the lateral bank retreat but increase the incision of the nearby riverbed, with the largest erosion depth of 10.6 m during August to November in 2020. (2) The initial damage in protected banks may be triggered by local tensile stress concentration during the water-rising period, under the combined actions of hydrostatic confining force, pore water pressure and gravity. This initial damage will progress into more severe bank failure events, particularly during the flood period. (3) After the regulation of the Three Gorges Project, the increased changing rate of river stage (∼1.6–2.5 fold) could potentially increase the risk of damage to protected riverbanks in the Middle Yangtze River.

Erosion wear analysis of heat exchange surfaces in a falling particle-based concentrating solar power system

Next generation concentrating solar power (CSP) plants that use solid particles as the heat transfer and storage medium provide opportunities for higher temperature operation, higher efficiency, and lower levelized cost. However, falling particles over component material surfaces can cause significant erosion, severely limiting the performance and operational service life of the components. An understanding of the particle erosion wear of heat transfer surfaces is imperative for designing components and operating conditions to minimize wear. Considering a shell-and-tube heat exchanger configuration, this study presents a computational analysis coupling falling particle flow around heat exchanger tubes and particle-scale erosion of the tube surfaces governed by the Finnie model. Several tube arrangements, particle flow and geometric parameters, and tube material parameters are systematically investigated for their effects on the erosion rate spatially and with time. Parameters that influence the erosion depth, the cumulative mass loss rate and the maximum erosion rate are elucidated. The results of the study may be used to help identify locations that experience the most erosion and devise ways for targeted erosion mitigation.

An improved method combined modified drag model and modified erosion model based on LES for solid-liquid multiphase flow and erosion with application in a 90° elbow

In various industrial processes, solid-liquid multiphase flows involving continuous carrier and discrete particle phases have erosion challenges. In this work, a modified drag model that considers the influence of turbulence intensity and a modified erosion model that considers the effect of low-angle impact are developed. An improved method combined modified drag model and modified erosion model based on LES is proposed for numerical simulation of solid-liquid multiphase flow and erosion. The commercial software ICEM for grid generation and ANSYS FLUENT for LES are used in the present work. In validation test of velocity distribution of solid-liquid multiphase flow in a vertical pipe, the mean relative error of the liquid phase pulsation velocity is 10.01 % for modified drag model, whereas the mean relative error is 16.11 % for original drag model. In validation test of the maximum erosion depth from a submerged impact test at a tilt angle of 45°, the relative error is 0.23 % for modified erosion model, while the relative error is 13.39 % for original erosion model. Then, the improved method is employed to compute the characteristics of solid-liquid flow and erosion in a 90° elbow. Particles have a significant influence on liquid flow in the shear layer area where the inner arch separation zone interacts with the main flow, and this influence is most pronounced at the position of r* = 0.3 at yd = 0.4D. At this position, particles result in 15.27 % reduction in liquid velocity and 8.75 % increase in turbulence intensity. The mean relative error of the elbow erosion rate by using the improved method is 16.95 %, whereas it is 31.34 % of the reference work. The erosion is affected by impact velocity, angle, and particle number, and the most significant parameter is the particle number in the severe erosion area.

(Invited) In-situ Evaluation of Brass Dezincification Corrosion Under Galvanostatic Polarization Combined with Video Observation

Brass is widely used as the applications involving water supply pipes and pipe heat exchangers owing to its good mechanical properties. One of the limiting factors for use of brass is the dezincification corrosion, which may cause the water leakage accident. In the dezincification corrosion, the selective dissolution of zinctakes place on the brass surface, and the porous copper rich layer is formed on the brass surface1,2. To clarify the dezincification corrosion behavior of brass, we have newly developed a real-time cross-sectional surface observation system to examine the dezincification corrosion behavior of brass6. Our group developed a real-time surface observation system combined with video imaging to investigate the dissolution behavior of metals3-5. Comparing to the previous works3-5, the developed system in the present study allows for an in-situ monitoring of metal or alloy cross-section during electrochemical measurement because the video of metal or alloy cross-section can be taken by an optical microscope combined with a charge-coupled device camera. We applied the developed method for the investigation of brass dezincification corrosion, demonstrating that the inhomogeneous dissolution was observed in the depth direction under galvanostatic polarization. The average erosion depth could be estimated from the cross-sectional surface images at each measurement time. The results indicated that the depth erosion rate was different at initial and later stages, implying the preferential dissolution of zinc or the simultaneous dissolution of zinc and copper on the brass surface. Based on the video images and potential changes of brass during the measurement, the detailed dissolution behavior was discussed in the present study.References H.W. Pickering, C. Wagner, J. Electrochem. Soc., 7, 114 (1967). Y. Hoshi et al., J Solid State Electrochem, 19, 3551 (2015). Y. Hoshi et al., J. Electrochem. Soc., 164, C450 (2017). Y. Hoshi et al., Surf. Finish. Soc. Jpn., 69, 34 (2018). Y. Hoshi et al., J. Electrochem. Soc., 165, C243 (2018).Y. Hoshi et al., Mater. Trans., 64, 885 (2023).

Investigating the bearing performance of the foundation under the combined effects of flood scouring and soaking

Bearing capacity degradation of foundations under the impact of the flood is one of the major reasons responsible for the collapse and damage to the rural buildings, posing a serious threat to the local village societies. Based on a case study of a rural building foundation had been destroyed by flooding. This paper investigated the deterioration process of rural building foundations under the combined effect of dynamic scouring and static soaking caused by flooding. Using the two-dimensional shallow water equation, erosion depth was calculated for different flood velocities. Then, the bearing capacity degradation under the combined scouring-soaking effect was analyzed using the finite element method. Finally, investigating the influence of inflow direction and building group masking on the foundation's bearing capacity. The results indicate that under the combined effect, the bearing capacity of village building foundations decreases by 47.88%, with scouring slightly more impactful than soaking. Inflow angle has minimal effect on bearing performance, while the masking effect of the building group provides better protection for the foundation of rear buildings.

Mechanical relationship between compressive strength and sulfate erosion depth of basalt fiber reinforced concrete

To mitigate the restraining effect of basalt fiber on the sulfate erosion damage in basalt fiber reinforced concrete, sulfate erosion experiments were carried out on both ordinary concrete and basalt fiber reinforced concrete. Changes in concrete strength in relation to sulfate erosion depth under various sulfate solutions and erosion ages were recorded. The mechanical relationship between the compressive strength and sulfate erosion depth was proposed. The results showed that the inflection point on the strength-erosion age curve for basalt fiber reinforced concrete appeared significantly later than that in ordinary concrete, indicating that basalt fiber can delay sulfate erosion and enhance concrete durability. Using the measured sulfate erosion depth, remaining compressive strength can be predicted.

Machine learning based prediction model for the pile bearing capacity of saline soils in cold regions

The difficulty in determining the bearing capacity of pile foundations in saline soil environments in cold regions can pose a challenge when developing a bearing capacity prediction model. To address this, the study uses data from the construction of the De Xiang Expressway project in Qinghai Province, China, and considers pile length, pile diameter, corrosion depth, and spalling thickness as influential parameters. We combine Python with ABAQUS to build a finite element model of a single pile in a salt marsh environment with random parameters and develop a database for machine learning. We use the kernel ridge regression (KRR) and multilayer perceptron (MLP) algorithms to establish load-bearing capacity prediction models for vertical and horizontal loads, respectively. The SHAP (SHapley Additive exPlanations) method is employed to perform explanatory analysis on the prediction models, providing insight into influential parameter effects on prediction accuracy. The results demonstrate that the database established through the random parameter finite element method is suitable for machine learning. While the KRR model exhibits good performance in predicting vertical load-bearing capacity, the MLP model performs well in predicting horizontal load-bearing capacity. Moreover, the SHAP method effectively explains the importance of influential parameters on the prediction results and enhances the reliability of the prediction models. The vertical bearing capacity of a saline soil pile foundation is more affected by the depth of salt erosion than the thickness of spalling, while the horizontal bearing capacity is more affected by the thickness of spalling than the depth of salt erosion.

2D and 3D Erosion Landscape Analysis of Endodontic-Treated Teeth Using EDTA and HEDP as Chelating Agents: A High-Resolution Micro-Computed Tomographic Study.

This study aimed to assess the amount of erosion during activated endodontic irrigation with either HEDP or EDTA via high-resolution micro-computed tomography. Two root canals of twenty premolars were prepared with ProTaper Next and irrigated with sodium hypochlorite. Palatal canals, which served as control groups, were sealed, while buccal canals were further irrigated with either EDTA (n = 10) or HEDP (n = 10), which served as test groups. Micro-CT was performed to measure erosion depth. For 2D and 3D measurements, non-parametric repeated ANOVA measurements and post hoc tests were performed. 2D analysis showed highly significant differences between the case groups at each position of the root (p ≤ 0.01). The cervical and apical positions showed significant differences in the EDTA group (p = 0.03). The 3D analysis also showed significant differences between both chelating agents (p < 0.01) and the case and control groups (p = 0.01). The mean erosion depths in the cervical, middle, and apical thirds of the EDTA group were 45.75, 41.79, and 32.25 µm, and for the HEDP group were 20.25, 16.40, and 15.96 µm, respectively. HEDP seems to have a significantly less erosive effect. Different irrigation protocols with harsher conditions, as might be the case during endodontic retreatment, could be assessed with micro-CT.

Time-depth dependent chloride diffusion coefficients of self-compacting concrete

Chloride attack severely impacts the performance of reinforced concrete. The total and free chloride ion concentrations (CICs) of self-compacting concrete (SCC) prepared with three supplementary cementitious materials (SCMs) - fly ash (FA), blast furnace slag (BS), and silica fume (SF) – were measured through the accelerated salt immersion tests. The apparent chloride diffusion coefficients (CDCs) at any exposure time and erosion depth were calculated using the Boltzmann-Matano method. The influence of the type and content of SCMs, the water-binder ratio (W/B), and the type of salt solution on CICs and CDCs were investigated. Both introducing SCMs and reducing W/B effectively reduced the CIC. The SCM that most effectively reduced CIC was SF, followed by BS and then FA. Free CICs were reduced to a greater degree than total CICs in FA and BS concrete, but the opposite was true for SF concrete. Presence of calcium chloride in salt solution increased total CICs while reducing free CICs. Apparent free CDC dropped over exposure time and initially increased with erosion depth but eventually stabilized. A model of apparent free CDC considering the time-depth dependence was created, which shows that time reduction factors of CDC is larger in SCM-containing SCC than in control SCC.

Evaluation of the Depth and Width of Cuts after Controlled-Depth Abrasive Water Jet Machining Using Low Pressure.

The presented paper is focused on the evaluation of material removal during machining via an abrasive water jet with a controlled depth of cut. In the introductory parts of the work, a theoretical analysis of water jet technology and an analysis of the current state of the problem are presented. The experimental part of the work is devoted to testing the effects of technological parameters on material removal from the point of view of the maximum erosion depth and volume loss of material during machining with a low water pressure of 50 MPa. The tested material was a Ti 6Al 4V titanium alloy. The experiments were carried out by changing the traverse speed of the cutting head, the mass flow of the abrasive and the angle of inclination of the cutting head, according to the DoE 33 experiment plan. The obtained values were evaluated using the method of variance (ANOVA) and regression analysis. Furthermore, the values of the width of the erosion track and the maximum and minimum erosion effects for both tested materials were evaluated.

Sedimentary architecture and evolution of a Quaternary sand-rich submarine fan in the South China Sea

Investigating the sedimentary architecture and evolution of sand-rich submarine fans is vital for comprehending deep-water sedimentary processes and enhancing the success rate of hydrocarbon resource exploration. Recent drilling activities in the Qiongdongnan Basin, northern South China Sea, have unveiled significant gas hydrate and shallow gas potential. However, exploration in this area faces substantial challenges due to the limited understanding of sandy reservoirs. Leveraging extensive newly acquired extensive 3D seismic data (~9000 km2) and well data, our study reveals five distinct deep-water depositional systems in the Quaternary Ledong Formation, including a submarine fan system, mass transport deposits, deepwater channel-levee systems, slope fans, and hemipelagic sediments. Notably, the targeted sand-rich submarine fan lies within the abyssal plain, situated at a water depth of 1300-1700 m. This fan exhibits a unique tongue-shape configuration and a SW-NE flow direction within the plane and spans an expansive area of ~2800 km2 with maximum length and width reaching 140 km and 35 km, respectively. Vertically, the fan comprises five stages of distributary channel-lobe complexes, progressing from Unit 1 to Unit 5. Their distribution ranges steadily increase from Unit 1 to Unit 3, followed by a rapid decrease from Unit 4 to Unit 5. Our results suggest that the occurrence and evolution of the submarine fan are primarily controlled by sea level fluctuation, confined geomorphology, and sediment supply. Specifically, sea level fluctuation and sediment supply influenced the occurrence of the submarine fan. Concurrently, the confined geomorphology in the abyssal plain provided accumulation space for sediments and shaped the fan into its distinct tongue-like form. In contrast to the deepwater channels within the deepwater channel-levee systems, the distributary turbidite channels within the submarine fan are marked by lower erosion depth with “U” shapes, greater channel width, and higher ratios of width to depth. The comparative analysis identifies turbidite channels as the focal points for offshore gas hydrate and shallow gas exploration in the Qiongdongnan Basin. Furthermore, the temporal evolution of submarine fan offers valuable insights into Quaternary deep-water sedimentary processes and hydrocarbon exploration within shallow strata of marginal ocean basins.

Integrated Dynamic Model for Numerical Modeling of Complex Landslides: From Progressive Sliding to Rapid Avalanche

Landslides are one of the most common catastrophic mass flows in mountainous areas. The occurrence of fragmentation leads to the evolution of the integrity and stiffness of the sliding mass. The changes in internal composition caused by basal erosion and entrainment make the dynamic evolution of landslides more complex. To consider these complex processes, physics-based dynamic models are often used to analyze the dynamic characteristics of landslides. However, the proprietary assumptions of dynamic models often limit their application to complex events. A single dynamic model is often not competent for the analysis of landslides with evolving dynamic characteristics. In this study, two dynamic models are effectively integrated according to the evolving characteristics of the landslide. The common effects of basal erosion and entrainment are also considered. The maximum sliding velocity, accumulation range, and erosion depth characteristics of this integrated dynamic model are more consistent with the field than those of the single dynamic model. Under the terrain conditions of this study, within a few seconds of the triggering stage, if the occurrence of disintegration is advanced by 2 s, the maximum impact area will increase by about 3.1% to 4.1%, and the maximum kinetic energy will increase by more than 20%. Simulation results indicate that the changes in the integrity of the landslide body significantly affect the evolution of subsequent landslide dynamic characteristics.

Experimental investigation of impact force variations during high-speed liquid impingement erosion

High-speed liquid impingement erosion occurs in many industrial settings. The erosion transition, which occurs after the incubation period of liquid impingement erosion, significantly changes the erosion behavior, such as the material erosion rate and surface roughness; however, when and how the transition occurs remains elusive. The study focused on the impact force exerted on a material by a liquid jet impact during the transition in high-speed liquid impingement erosion. To this end, the force acting on an aluminum specimen attached to a force sensor during liquid impingement erosion was examined experimentally. The critical condition, which indicates the beginning of the accumulation stage of erosion, was detected through mass-loss measurements and visual observation of the target material. The results demonstrated a distinctive transition in the impact force with respect to the exposed flow volume. Additionally, a dynamic mode decomposition technique was employed to analyze variations in the impact force. Finally, the mechanism underlying the long-term variation in the impact force was discussed, and the correlation between the impact forces and erosion depths during high-speed liquid impingement erosion was presented.

Evaluation of atomic oxygen fluences by analyzing transmitted light images of polyimide obtained at SLATS/MDM

Expectations for high-resolution observations by very low Earth orbit (VLEO, below 300 km) satellites are growing. However, the density of atomic oxygen (AO) is much higher in VLEO than in LEO (300 km or higher), so severe degradation of materials is a concern due to high-flux AO collisions. To clarify the degradation, we developed and deployed the material degradation monitor (MDM) mission onboard the super-low altitude test satellite (SLATS). In the MDM, several materials were exposed to the environment at 160–560 km from 23 December 2017 to 1 October 2019 and observed optically by a CCD camera. In general, AO fluence is evaluated by measuring the volume or mass loss of a polyimide, but this was difficult to do because the samples could not be returned to the ground in this mission. This study evaluated AO fluences using the CCD images of a polyimide, Vespel. The sample had nine non-penetrating holes with different bottom-plate thicknesses and was monitored by the CCD while being illuminated by LED light from the back. The CCD images reveal the intensity of the light transmitted through the holes in the bottom plate. The erosion depths of the polyimide, corresponding to the AO fluences, can be evaluated from the pixel values at the hole positions on the images. Here, the correlation between the pixel values and thickness was investigated for pristine and AO-exposed Vespel samples using the MDM engineering models. The total green pixel values followed the Beer-Lambert law for the bottom-plate thicknesses, regardless of AO exposure. Applying the correlation to the MDM flight images, we found that the AO fluence increased significantly after the end of March 2019, finally reaching (6.5–9.8) × 1021 atoms/cm2. This optical imaging method would be useful for evaluating the AO effects on the other MDM samples and high AO fluences in future VLEO missions.

A Review on the Impacts of Toposequence on Soil Properties

This study demonstrates the significant influence of toposequence position on soil properties and hydrological conditions, affecting crop yield. Variations in toposequence position lead to differences in soil properties; physical and chemical properties may vary minimally or maximally depending on the slope’s location. As slope increases, soil moisture and organic carbon rise, while bulk density, pH, and soil temperature decrease. Soils along a toposequence reveal that landscape position, erosion, aspect, and drainage impact soil depth, particle size distribution, and CEC. Understanding topography’s influence on soil characteristics is crucial for evaluating soil productivity and devising conservation strategies. This knowledge is essential for assessing soil value and avoiding uneven input distribution in agricultural fields on diverse terrains. This review paper summarizes the impacts of toposequence on soil physical and chemical properties. The study utilized databases such as Google Scholar, African Journals Online (AJOL), Scopus, Web of Science, ScienceDirect, and Directory of Open Access Journals (DOAJ) to identify relevant studies.

Prediction of maximum scour depth in river bends by the Stacking model

Abstract The accurate prediction of maximum erosion depth in riverbeds is crucial for early protection of bank slopes. In this study, K-means clustering analysis was used for outlier identification and feature selection, resulting in Plan 1 with six influential features. Plan 2 included features selected by existing methods. Regression models were built using Support Vector Regression, Random Forest Regression (RF Regression), and eXtreme Gradient Boosting on sample data from Plan 1 and Plan 2. To enhance accuracy, a Stacking method with a feed-forward neural network was introduced as the meta-learner. Model performance was evaluated using root mean squared error, mean absolute error, mean absolute percentage error, and R2 coefficients. The results demonstrate that the performance of the three models in Plan 1 outperformed that of Plan 2, with improvements in R2 values of 0.0025, 0.0423, and 0.0205, respectively. Among the three regression models in Plan 1, RF Regression performs the best with an R2 value of 0.9149 but still lower than the 0.9389 achieved by the Stacking fusion model. Compared to the existing formulas, the Stacking model exhibits superior predictive performance. This study verifies the effectiveness of combining clustering analysis, feature selection, and the Stacking method in predicting maximum scour depth in bends, providing a novel approach for bank protection design.

&lt;i&gt;i&lt;/i&gt;-MSE: A Fine Structure Imaging for Surface and Its Inside of Solid Material with Micro Slurry-Jet Erosion Test

We propose a fine structure imaging for the surface and its inside of solid material such as coated drill bits with TiN (Titanium Nitride). We call this method i-MSE (innovative MSE) since the fine structure is visualized with a local mechanical strength (the local erosion rate) which is obtained from a set of erosion depth profiles measured with Micro Slurry-jet Erosion test (MSE). The local erosion rate at any sampling point is estimated from the depth profile using a sliding window regression and for the rest of the 2-dimensional points it is interpolated with the mean value coordinate technique. The interpolated rate is converted to a 2D image (i-MSE image) with a color map. The i-MSE image can distinguish layers if the testing material surface is composed of coats which have different resistance to erosion (erosive wear), while microscopic image such as SEM (Scanning Electron Microscope) and a calotest just provides appearance information, not physical characteristics. Experiments for some layered specimens show that i-MSE can be an effective tool to visualize the structure and to evaluate the mechanical characteristics for the surface and the inside of solid material.

Comparative study on the water droplet erosion behavior between stretched and casted aeronautical PMMA

Rain droplet erosion is a potential threat in aviation, especially for forward-facing components such as windshields of aircraft. To comprehend and mitigate such hazards, a comparative study was conducted on two kinds of commonly used aeronautical PMMA materials: casted and biaxially stretched. The study aimed to investigate the water droplet erosion (WDE) behavior and the underlying damage mechanism. A modified pulsed water jet erosion facility was constructed to mimic the impact of successive water droplets. The influence of impact velocity on the WDE behavior was explored and quantitative evaluations of volume loss, surface entrance area, and erosion depth were conducted. Results revealed that the increase in impact velocity leads to faster damage initiation and a larger erosion rate. Compared with the stretched sample, the casted sample exhibits higher erosion resistance. The stretched sample exhibits a funnel-shaped cavity with a flat bottom, while the casted sample shows a tapered crater with shallow depth. The cavity shape can influence the subsequent flow fields and stress distribution, thereby affecting the development of erosion entrance and depth. Microscopic analysis of the erosion cavities revealed different damage mechanisms at each stage of erosion. The stretched sample exhibited exfoliation of fine flakes and denudation of large pieces due to stress waves and lateral jet-induced shear, whereas hydraulic penetration had a more pronounced effect on the casted sample. The cushioning effect of the water film was also studied, noting a gradual reduction in its effectiveness with increasing impact velocity.