Cohesive Elements Research Articles

Characteristics of Penetration Strength and Fracture Features under Nonuniform Stress Field around Borehole Surrounding Rock.

In the process of mining coal energy, the excavation of roadways and drilling causes the formation of a nonuniform stress field around the penetration holes, which will lead to a significant concentration of stress around the penetration hole. It even leads to the destruction of the surrounding rock of the penetration hole, affecting the integrity of the surrounding rock of the penetration hole. It has an effect on the strength of the rock obtained by the borehole penetration methods. Based on Abaqus software, the numerical model of borehole penetration was constructed by embedding cohesion elements between solid elements. After analyzing the simulation results obtained under different stress boundaries and penetration directions, the following findings are obtained. (1) Using the occurrence of cracks in the borehole surrounding rock as the criterion, the rock is categorized into either an elastic stress state or a plastic stress state after applying different stress boundary conditions. (2) When the borehole surrounding rock is in the elastic (plastic) stress state, the penetration strength increases (decreases) with the increase of lateral pressure coefficient. (3) In the elastic stress state, borehole surrounding rock's fracture area and crack penetration depth increase (decrease) with the increase of lateral pressure coefficient when the penetration direction is parallel (perpendicular) to the maximum principal stress. In the plastic stress state, the fracture area increases, while crack penetration depth decreases with higher lateral pressure coefficient.

Modelling dynamic fracture and fragmentation of rocks under multiaxial coupled static and dynamic loads with a parallelised 3D FDEM

In this study, a three-dimensional (3D) combined finite-discrete element method (FDEM) based simulator, which enables the robust simulation of full-scale triaxial Hopkinson bar (Tri-HB) testing system, including the capture of fracture and fragmentation processes of rock specimens as well as the detection and analysis of generated rock fragments, is developed for investigating the dynamic responses of rocks subjected to multiaxial coupled static and dynamic loads. An innovative two-step approach is proposed to first efficiently achieve the static stress state in the entire Tri-HB system and then apply dynamic loading to the system. The proposed approach with the schemes of mass scaling and local damping can significantly reduce the run time for static computation involving cohesive elements and complex contact mechanics in the framework of explicit time-integration. The developed program is well validated by achieving dynamic stress equilibrium in the Tri-HB system and comparing the simulated stress wave profiles with those from laboratory experiments. Then, the progressive dynamic fracture and fragmentation processes of rocks under different static stress conditions in a full-scale Tri-HB system are investigated, which vividly exhibit the confinement dependence of the dynamic behaviours of rocks in the testing system. It is found that, even with the same loading rate, separate input parameter sets for rock need to be established in FDEM for different confinement conditions to capture the actual rate dependent behaviour of rock. Further studies are also conducted to investigate the effect of interfacial friction on the fracture behaviour, and the results indicate that higher interfacial frictions significantly disturb the dynamic stress variations and the true rock behaviour in the system. Through high performance computing of 3D FDEM, this study is expected to contribute to the understanding of dynamic responses of rocks subjected to multiaxial coupled static and dynamic loads in deep underground engineering.

Application of neural fatigue cohesive element to R-DCB model with in-situ training strategy

In this work, a recently developed fatigue delamination growth (FDG) simulation tool driven by neural network (Neural Fatigue Cohesive element, NFCOH) is validated using a benchmark model that offers complex crack front known as the R-DCB model. The NFCOH is tested using two different training strategy for the driving neural network, i.e., a regular training strategy and an in-situ training strategy. For the regular training strategy, virtual samples based on material fatigue properties in the form of Paris parameters are generated to train the neural network. Whilst for the in-situ training strategy, samples are generated using non-destructive testing (NDT) results of the R-DCB model. The results for both strategies are presented and compared to demonstrate the advantages as well as disadvantages of each strategy and NFCOH in general.

Direct FE2 Based on Single-Integration Point for Modeling Damage Evolution of Materials with Micro-Cracks

The Direct FE2 method is a recently developed concurrent multi-scale simulation approach with a monolithic solution scheme, where the macroscopic and microscopic models are solved in a unit iteration process. The conventional Direct FE2 using quadrilateral element has some limitations in determining the failure state of a macro-element. In this work, we develop a new Direct FE2 method based on the Single-integration Point triangle element (Direct SP-FE2) and apply it to simulate the micro-crack-induced fracture problems for the first time. The cohesive element is inserted into a representative volume element (RVE), so that the failure process of a macro-element can be determined by the micro-crack propagation on RVE. Accordingly, the relationship between macro-deformations and microstructures can be established directly, thus avoiding complex derivation and utilization of a multi-scale damage constitutive model. In Direct SP-FE2, the failure state of a macro-element can be directly predicted by the RVE at the single-integration point inside, avoiding the uncertainty associated with predictions by multiple RVEs. As a result, compared to the conventional Direct FE2 with a quadrilateral element, the Direct SP-FE2 shows advantages in capturing complex geometric boundaries and predicting the damage evolution process and failure state more accurately. Various numerical examples are conducted to comprehensively validate the effectiveness of the present method in describing the influence of micro-cracks on macro-structure deformations. For the macro-damage behaviors, the simulation results by the Direct SP-FE2 show good agreement with the direct numerical simulation (DNS) results of the full FE model at a significantly lower computational time. With the developed Direct SP-FE2, a variety of complex micro-crack fracture problems in composite materials can be successfully modeled by manipulating the interior RVE structure.

Simulation and Experimental Study of Mooring Function Composite Fragile Cover

Abstract Under the requirement that the fragile cover does not eject debris during missile launches, and to meet the demands of rapid combat, there is an urgent need for a lightweight missile launching system. Enhancing the effective utilization area of the fragile cover is an effective way to realize the lightweight of the missile launching system. This paper utilizes the properties of carbon fiber composite materials to design a novel frangible cover with mooring functionality and establishes numerical models for the cover’s pressure and bursting dynamics. In the pressure finite element model, the Tasi-Wu failure criterion is employed for damage assessment. In the bursting dynamics finite element model, a cohesive element is used to simulate the elastic behavior and damage evolution of the weak area, while a membrane element is employed to simulate the mooring function. Comparative analysis of numerical results with experimental data reveals minor discrepancies, with errors of 5.44% for maximum deformation under pressure and 8.1% for bursting force, respectively, validating the model’s rationality and effectiveness. Results from both experimental tests and finite element analyses demonstrate the successful implementation of mooring functionality in the segmented body. The effective utilization area of the cover was increased by 71.13%. This research provides a feasible direction for subsequent studies on non-ejecting frangible covers.

GPU-accelerated approach for 2D fracture analysis of structures combining finite particle method and cohesive zone model

The fracture analysis of structures typically involves strong discontinuity and nonlinear behaviors, and it requires fine meshing and small time steps, making it time-consuming. This study proposes an approach accelerated by graphics processing units (GPU) for two-dimensional (2D) fracture analysis of structures combining finite particle method (FPM) and cohesive zone model (CZM). Specifically, the equations of motion of particles are presented, and the internal forces of planar triangular elements are derived based on FPM. Subsequently, the internal forces of four-particle cohesive element are derived to describe the CZM, and the linear elastic stage, softening stage, and failure stage are depicted according to the traction-separation criteria. An explicit GPU-based FPM analysis strategy for structural fracture analysis is then developed, and the parallel solvers for particles, triangular elements, and cohesive elements are implemented. A quasi-static fracture analysis of a concrete beam and a dynamic fracture analysis of the Kalthoff problem is conducted to verify the effectiveness of the proposed approach. The obtained crack propagation path, load vs. displacement curves, and crack propagation speed are in good agreement with the experimental results and the results in the literature. The efficiency of the proposed approach is also investigated. The achieved maximum speedup ratio of the GPU-accelerated approach to the central processing unit (CPU)-based approach reaches around 24, and the achieved speedup ratio relative to the commercial finite element software Abaqus/Explicit reaches around 11.5, demonstrating the computational efficiency of the proposed approach.

ROOT ZONE TECHNOLOGY FOR WASTE WATER TREATMENT

In India, the primary cause of surface and ground water pollution is the discharge of untreated sewage, according to a 2007 study by the Central Pollution Control Board. In India, there is a significant delay between the generation and treatment of household wastewater. India's insufficient treatment capacity is not the only issue; there are also sewage treatment plants that exist, but they are not being maintained or operated. Because of poor design, inadequate maintenance, unreliable electricity supplies, absentee staff, and incompetent management, the majority of government-owned sewage treatment plants remain closed for the most part of the year. Usually, the wastewater produced in these places evaporates or percolates into the soil. Uncollected waste builds up in urban areas, releasing pollutants that seep into surface and groundwater and creating unsanitary conditions. Furthermore, industrialists prefer not to treat the waste produced and instead to dump it untreated into rivers in the areas where these treatment plants are located because the cost of treatment is so high.The Root Zone Treatment System (RZTS), sometimes referred to as the reed bed system or the constructed wetland system, is a sealed filter bed that is planted with vegetation that can grow in wetlands and is made up of a sand, gravel, and soil system, sometimes with a cohesive element. The wastewater flows through the filter bed, where biodegradation of the wastewater occurs, after the coarse and floating material has been removed. Complex physical, chemical, and biological processes that are the outcome of the interaction of wastewater, wetland plants, filter bed material, and microorganisms define the functional mechanisms in the soil matrix that are in charge of the mineralization of biodegradable matter.

Effects of printing patterns and loading directions on fracture behavior of 3D printed Strain-Hardening Cementitious Composites

Strain-Hardening Cementitious Composites (SHCC) have gained widespread attention as self-reinforcing materials in 3D concrete printing. Meanwhile, owing to the layer-by-layer build-up process during extrusion-based 3D printing, interfaces have a significant impact on the fracture behavior of 3D printed concrete. In this study, 3D printed SHCC (3DP-SHCC) specimens were prepared with two printing patterns: parallel-printing and cross-printing. Cubic compressive strength tests and three-point bending tests on notched beams were conducted. The results showed that the compressive strength of 3DP-SHCC was 1.23 ∼ 1.45 times higher than that of mold-cast SHCC. Parallel-printed SHCC exhibited a significant degree of anisotropy. The initial and unstable fracture toughness (KICini, KICun), flexural strength (Ff), and fracture energy (Gf) of parallel-printed SHCC in the X direction were 1.31, 1.81, 1.39, and 1.79 times those of mold-cast SHCC, respectively. In comparison, the cross-printed SHCC showed significantly lower anisotropy in the X and Y directions. By incorporating cohesive elements with the cohesive damage plasticity model, the fracture behavior of the 3DP-SHCC could be accurately simulated.

A novel multiscale prediction strategy for simulating the progressive damage behavior of plain-woven bamboo fabrics reinforced epoxy resin composites

This study proposed a novel multiscale prediction strategy, including mesoscale and macroscale damage evolution modeling, to investigate the effective properties and progressive damage failure behavior of plain-woven reinforced composites (PWRCs) under various external loads (tension, compression). A high-precision mesoscale representative volume element (RVE) that could accurately describe the local mechanical behavior of PWRCs was developed by combining experimental characterization (scanning electron microscope and X-ray computed tomography) and numerical simulation. To solve the problem of inaccurate prediction results caused by multiscale characteristics and complex stress changes in the damaged area of PWRCs, the strain-based 3D Hashin failure criterion and the multiscale damage models were used to predict the damage initiation and evolution of mesoscale reinforcement (bamboo fiber yarn bundle) and macroscale composites, respectively. Considering the damage evolution law of isotropic materials, a damage model based on the Von Mises criterion was used to characterize the damage initiation and evolution of mesoscale matrix epoxy resin (EP) under external loading. The effective properties and mechanical behavior of the PWRCs were transferred from mesoscale to macroscale through the progressive homogenization method. The bilinear constitutive relationship of the mixed-mode cohesive element was used to characterize the interlaminar failure of the PWRCs. Finally, the corresponding mechanical characterization (tension, compression) of the PWRCs was carried out. Moreover, the experimental results were highly consistent with the simulation results, verifying the reliability of the novel multiscale prediction strategy in investigating the mechanical response of the PWRCs at multiple scales and revealing the damage mechanism of the PWRCs.

Progressive damage modeling in open hole composite laminates with ultrasound-informed drilling-induced delamination

Insertion of fasteners, often used in aerospace and automotive industries, requires drilling that induces non-uniform delamination between lamina of a carbon fiber reinforced plastic (CFRP). Understanding the effect of drilling-induced delamination on the mechanical performance and associated damage mechanisms (progressive damage and failure) is critical to ensure joining integrity. The present work develops an ultrasound testing (UT) method to quantify the drilling-induced delamination at each individual ply interface for CFRP laminates. We then develop a mesoscale finite element (FE) model of an open hole tension specimen by incorporating the UT-obtained drilling-induced delamination at each interface. This delamination is modeled using cohesive zone elements with a bilinear traction-separation law with progressive damage in each ply modeled using the 3D Hashin along with a progressive damage model. Our FE model, with UT-informed delamination, accurately predicts experimental observations of the stress concentration around the hole, damage progression, and open hole tension strength.

Assessment of Reinforcement Effect of FRP-Strengthened Shield Segment Joint Based on the CZM Model

As the weakest link in the shield segment, the reinforcement and repair technology of shield segment joint has received widespread attention. In this study, an finite element model utilizing a cohesive zone model (CZM) was constructed to simulate the mechanical behavior of the shield segment joint during the whole fracture process. The proposed modeling method of joint allows multiple layers of steel bars to be stacked without interference by applying cohesive elements. Cohesive elements were employed to represent the mechanical response of potential fracture surfaces in concrete, as well as the interfaces between steel–concrete and fiber-reinforced polymer (FRP)–concrete, by utilizing various constitutive models tailored for mixed-mode loading conditions. A group of experiments was chosen to assess the precision of the proposed model by comparing the mechanical response and the fracture patterns. Finally, parameter analyses were conducted to study the reinforcement effect of the FRP bonding length and width on the shield segment joint. The results indicate that external bonding of FRP can effectively enhance the bearing capacity and stiffness of shield segment joints. However, insufficient bonding length or width may significantly reduce the strengthening effect and potentially decrease the ductility of the joint.

Revealing the grain boundary effect on interfacial adhesion in polycrystal Fe/Ni interfaces by using a multi-scale CZM-CPFEM approach

In layered structure, interface plays a significant role in property improvement, whereas its multiple factors at various length scales restricted further understanding. Previous research found a novel grain boundary (GB)-interface interaction: crack initiation locally occurred at the junctions between pre-existing GBs and interface. This leads to decreased interfacial strength. To clarify the mechanisms of such GB-interface interaction, the present study proposed a multi-scale cohesive zone model-crystal plasticity finite element method (CZM-CPFEM) model to investigate the effect of pre-existing GB on intrinsic bonding strength at atomic scale and interfacial stress distribution at micro scale, respectively. At atomic scale, interfacial fracture criteria were modelled according to Molecular Dynamics (MD)-based traction-separation relationships. The accuracy of CZMs was improved by considering both isothermal holding and tilting configuration effects. At micro scale, a practical interfacial microstructure was used to construct CPFEM models. Tensile simulations showed that the local stress concentration occurred at junctions, attributed to the anisotropic plastic deformation behaviours across the GB. On the other hand, weak bonding adhesion at the junction only affects the local crack initiation strength, showing insignificant impacts on the overall interfacial fracture behaviour.

Cracking of soft collagenous tissues under suture retention

Soft collagenous tissues consist of collagen fibers and soft matrix, such as skin, muscle, and heart valve, etc. Suture of the tissues is ubiquitous in surgery, which may cause fracture of tissues due to inevitably introduced defects. However, the cracking mechanism of soft collagenous tissues under suture retention remains elusive. Herein, we use bovine pericardium as a model tissue to study the suture related fracture considering various fiber orientations. Fracture tests reveal distinct toughness and fracture modes of the tissue depending on the fiber orientation, such as crack propagation and crack deflection. The maximum J-integral criterion has been established to predict the direction of crack propagation in the tissue. We further conduct suture retention test to evaluate the suture resistance of tissues, and find two different failure modes: fracture and cutting. Microscopic examination of the fracture surface demonstrates that the tissue can rupture with long fiber pullout, cut through matrix failure, or cut by a combination of fiber break and pullout. The cohesive element model is used to analyze the cutting mode. The predicted failure modes and force-displacement curves match well with experiments. This paper may provide guidance to surgical operations and benefit new artificial collagenous materials.

The influence of bedding interface strength on the vertical propagation of hydraulic fractures

Bedding interfaces in unconventional oil and gas may influence the vertical propagation path of hydraulic fractures. In this article, the cohesive elements were used to describe the tensile and shear damage of bedding interfaces. The vertical propagation law of hydraulic fractures under different stress, bedding interface tensile strength, and shear strength conditions was calculated. The simulation result revealed three types of hydraulic fractures: “H”-shaped, “fishbone”-shaped, and “I”-shaped fractures. The large vertical stress can cause difficulties in damaging bedding interfaces. When the vertical stress difference lies between 0 and 5 MPa, complex fishbone-shaped fractures can easily form. However, when the vertical stress exceeds 5 MPa, “I”-shaped fractures are more likely to occur. In case the vertical stress difference is less than 0 MPa, hydraulic fractures may encounter obstacles in crossing the bedding interface, resulting in the formation of “H”-shaped fractures. A larger tensile strength of the bedding interface will promote hydraulic fractures to pass through the bedding interface and make it easier to form “I”-shaped fractures, promoting the growth of fracture height, which promotes fracture height growth. On the other hand, a low shear strength in the bedding interface can cause shear slip, resulting in the formation of “H”-shaped fractures, which inhibits the growth of fracture height. Tensile shear mixed damage typically happens at the bedding interface. This type of damage can restrict the vertical propagation of hydraulic fractures, but it can also make the fractures more complicated.

Prediction of peel strength of sandwich sheets made of aluminium alloys fabricated by friction stir spot welding based hybrid process using cohesive zone modeling and finite element simulations

The present work examines the fabrication and numerical modelling of honeycomb core sandwich sheets utilizing Friction Stir Spot Welding (FSSW) techniques as prospective substitutes for adhesive-bonded structures. Here, the sandwich sheet contains AA5052-H32 skins and AA3003 honeycomb core. Two strategies, FSSW with disc insert (FSSW_D) and FSSW with disc insert and adhesive bonding (FSSW_D_AB), were evaluated against traditional adhesive-bonded sandwiches using peel test performance and finite element (FE) simulation with cohesive zone modelling (CZM). In the CZM, a homogenized core with an equivalent cohesive layer was substituted for the honeycomb core and cohesive layer. The utilization of FSSW_D and FSSW_D_AB methods resulted in substantial improvements in maximum load capacity, with enhancements in the hybrid sandwich specimen ranging from 254 % to 399 % compared to adhesive-bonded connections. The maximum load of hybrid joints (FSSW_D_AB) was 15 %–23 % higher than that of ordinary spot-welded joints (FSSW_D). An approach to model the hybrid sandwich specimen using both the homogenized core and equivalent cohesive zone model accurately was proposed. FE analysis, including peel tests of adhesive-bonded, spot-welded, and hybrid joints, was performed, and the numerical predictions agreed satisfactorily with the experimental values for all the joint types.

A Dynamic Propagation Numerical Model of Hydraulic Fracture Interactions with Pre-Existing Complex Natural Fractures

The propagation of hydraulic fractures is highly influenced by the geological structure of the reservoir in unconventional reservoirs, such as natural fractures. In this paper, a new fluid–solid coupling dynamic model was built which presents the failure mechanism of hydraulic fracture with pre-existing simple and complex natural fractures. The cohesive element method and the maximum principal stress fracture criterion were used in the new model. An analysis was conducted to investigate the impact of various factors, including encounter angle, in situ stress, elastic modulus, and Poisson’s ratio, on the propagation of hydraulic fractures. The simulation results indicate that the encounter angle and the in situ stress are the main factors affecting the fracture morphology. When the encounter angle and the in situ stress difference are small, hydraulic fractures propagate along natural fractures. When the elastic modulus is small, it is advantageous for the advancement of both hydraulic and natural fractures. The Poisson’s ratio has a slight effect on the fracture propagation pattern.

Simulation and experimental research on longitudinal-torsional ultrasonic vibration drilling of CFRP/Ti laminates

Carbon fiber reinforced polymer (CFRP) and titanium alloy (Ti) laminated materials are extensively employed as primary load-bearing structures in aerospace engineering due to their exceptional characteristics. During the drilling process of CFRP/Ti laminates, issues like delamination and burr formation significantly impede the overall performance of these laminates. The finite element simulation was carried out to address above challenges using longitudinal-torsional ultrasonic vibration drilling (LT-UVD) of CFRP/Ti laminates. A three-dimensional solid model of CFRP/Ti laminates was developed using the ABAQUS custom VUMAT subroutine interface. A cohesive element was skillfully incorporated into the model to simulate delamination defects in the CFRP material effectively and to elucidate the material damage trends and stress distribution throughout the drilling process of laminated materials. The results obtained from the finite element simulation are meticulously compared with experimental data, revealing a consistent trend in the axial force curve. The simulated axial force’s peak value is 14.45% lower than the peak value obtained from experimental observations. The findings of this research substantiate the efficacy of the developed finite element model for LT-UVD of CFRP/Ti. The model successfully predicted the changing trend of axial force and layered defects during the drilling process. Moreover, it provides a visually intuitive instantaneous cutting state and stress distribution, imparting valuable insights into the intricate drilling mechanisms involved in CFRP/Ti laminates.

Numerical Simulation of Transverse Crack on Composite Structure Using Cohesive Element

Due to their anisotropic behavior, composite structures are weak in transverse direction loading. produces transverse cracks, which for a laminated composite, may lead to delamination and total failure. The transition from transverse crack to delamination failure is important and the subject of recent studies. In this paper, a simulation of transverse crack and its transition to delamination on cross-ply laminate was studied extensively using a cohesive element Finite Element Method (FEM). A pre-cracked [0/90] composite laminate made of bamboo was modeled using ABAQUS/CAE. The specimen was in a three-point bending configuration. Cohesive elements were inserted in the middle of the 90° layer and in the interface between the 0° and 90° layer to simulate transverse crack propagation and its transition to delamination. A load–displacement graph was extracted from the simulation and analyzed. As the loading was given to the specimen, stress occurred in the laminates, concentrating near the pre-cracked region. When the stress reached the tensile transverse strength of the bamboo, transverse crack propagation initiated, indicated by the failure of transverse cohesive elements. The crack then propagated towards the interface of the [0/90] laminates. Soon after the crack reached the interface, delamination propagated along the interface, represented by the failure of the longitudinal cohesive elements. The result of the numerical study in the form of load–displacement graph shows a consistent pattern compared with the data found in the literature. The graph showed a linear path as the load increased and the crack propagated until a point where there was a load-drop in the graph, which showed that the crack was unstable and propagated quickly before it turned into delamination between the 0o and 90° plies.

Study on the extension mechanism of hydraulic fractures in bedding coal

This study is aimed at investigating the formation process and extension mechanism of hydraulic fractures (HFs) in bedding coal. To achieve this aim, a numerical model of hydraulic fracturing of bedding coal was established based on the cohesive element. Furthermore, the influences of stress field, bedding dip angle and fracturing fluid displacement on the extension law of HFs in bedding coal were studied, and the formation process and extension mechanism of HFs in bedding coal were analyzed. The following beneficial results were obtained. HFs prefer penetrating the bedding plane when extending towards it at a large angle, while they tend to extend along the bedding plane when the angle is small. Under certain stress field conditions, during hydraulic fracturing, changing the extension direction of original HFs enables HFs to develop into a complex fracture network under the combined effect of bedding structure and stress field. Meanwhile, altering injection displacement can enlarge the extension range of HFs on the bedding plane. The principle can be explained as follows: under the action of continuous unstable pressure waves caused by fluctuant injection displacement, coal is likely to undergo fatigue damage, which further promotes the generation of micro cracks within coal and facilitates the opening and extension of HFs. The pore pressure near HFs increases linearly with the rise of fluid pressure in HFs, decreases linearly with the growth of distance from HFs, and is inversely proportional to the square root of the fracturing fluid’s filtration time. After HFs penetrate the bedding plane, coal is prone to shear failure and further generates secondary fractures under the filtration effect of fracturing fluid. Under the joint effect of fracturing parameters such as bedding, ground stress and displacement, main HFs and secondary HFs can intersect to form a complex fracture network when penetrating the bedding plane.

Simulation of TiN/Ti Multilayer Coating under the Impact of Multiple Particles Based on Cohesive Element

In order to investigate the damage behavior of TiN/Ti multilayer coating under multi-particle impact and the influence of impact angle on erosion resistance, the ABAQUS 2019 software and the cohesive element technology were used for simulation. The results showed that, during the impact process, the upper surface of the TiN layer that was directly below the impact center was mainly subjected to compressive stress, while the lower surface was subjected to tensile stress. At the impact contact edge, tensile stress appeared on the upper surface of the TiN layer, while compressive stress appeared on the lower surface. The increase in the number of impacts leads to an increase in the maximum S11 stress inside the coating and the maximum displacement of the impact center during the impact process. The plastic damage was greater at the locations with higher strain in the Ti sublayer. During the impact process, severe damage occurred in both the top TiN layer and interface areas, and material failure occurred in the impact area. The increase in impact angle leads to an increase in the plastic strain energy of the entire model after the impact and the maximum S11 stress inside the coating during the impact process.