Impact Damage Model Research Articles

Characteristics of Particle-Wet Wall Impact Damage: Effects of Liquid Film Parameters

Particle impact damage significantly affects the safe and stable operation of energy and chemical process equipment. During particle transportation, a liquid film may form on the wall, influencing the damage mechanism caused by particle effect. This study investigates the effects of liquid film parameters, specifically viscosity and thickness, on wall damage. Hydroxypropyl Methylcellulose (HPMC) solution was applied as a liquid film, and the effect of the liquid film's viscosity and thickness was examined through impact damage experiments using a particle (45 steel) and a wall (1060 aluminum alloy) with the liquid film. Results indicate that the presence of a liquid film can inhibit wall damage. Increased liquid film viscosity and thickness reduce wall damage, but they affect the turning points of damage characteristic parameters differently concerning impact angle and velocity. Finally, the study establishes correlation between dry and wet impact by introducing the effect coefficient of liquid film. This reveals the alteration rules of the influence coefficient and proposes a wet impact damage model, providing a reference for the damage prediction in process equipment.

Damage Assessment of Low-Velocity Impacted Sandwich Composite Structures Using X-Ray Micro-Computed Tomography

Sandwich composite structures offer significant versatility in structural system design but are susceptible to low-velocity impact damage, impacting their structural robustness. This study focused on nondestructive testing, particularly using X-ray micro-computed tomography, to assess damage on these structures, comprised of thin glass fibre reinforced polymer face sheets and a polyvinyl chloride foam core, under low-velocity impacts. Impacts were induced by a constant mass of 5.61 kg, dropped from various heights, generating impact energies between 2 and 22 J. This resulted in varied damage levels, from indentations to full perforations. The X-ray micro-computed tomography technique was chosen for its ability to detect internal damage. However, the system’s efficacy in accurately assessing damage depends on numerous factors like focus-to-detector distance, focus-to-object distance, and spatial resolution of the detector, among others. The system yielded an approximated resolution range of 10–25 μm for a focal spot size of 4 μm and the resolution range of 11–26 μm for a spot size of 7 μm. To this end, the system was able to reveal damage inflicted across the specimen through captured and reconstructed images. The quality of the reconstructed images was validated using ImageJ2 software by comparing with the processed images. The median filter was found to deliver images that closely resembled the original ones, albeit with a slight reduction in quality. Damage types varied based on impact energies. Low-level impacts caused matrix cracking and delamination at the foam interface. Medium-level impacts led to intralaminar and interlaminar damage, fibre fractures, and significant damage to the foam core through shearing and crushing. High-level impacts resulted in near or full perforations, with more pronounced delamination at the bottom interface, and fibre fractures in the impact zone, displaying a distinctive diamond-like damage pattern. These findings can be instrumental in developing a predictive impact damage model.

Strain rate-dependent failure modelling of impact damage in laminated CFRP structures

This work focuses on the development, implementation, and validation of a constitutive model for unidirectional composites, aiming to numerically simulate impact damage in laminated structures. The model incorporates a failure criterion that accounts for the influence of strain rate on failure initiation and distinguishes between four failure modes. Failure initiation criteria are 3D phenomenological-based criteria according to the previous work of Puck and Schürmann (1998) and Pinho (2006). Additionally, a mesh-objective damage propagation model is implemented to simulate the impact damage. The impact simulations are performed using Abaqus/Explicit, with the constitutive model implemented through the user subroutine VUMAT. Validation of the strain rate effects on failure initiation is performed using strain rate-dependent bi-axial failure curves for IM7/8552 and AS-4/3506. The analyses indicate that the properties governing the strain rate dependence of failure initiation are consistent. Therefore, the hypothesis was tested in which the same strain rate scaling approach could be used for CFRP materials for which only static properties are available. This hypothesis was tested in high and low-velocity impact simulations at laminated IMS60/977–2 CFRP plates. The results demonstrate that the model accurately replicates the experimentally observed impact-induced contact forces and effectively captures the damaged state in the impacted plate.

Comparison of X-ray Computed Tomography and Ultrasonic C-Scan Techniques and Numerical Modelling of Impact Damage in a CFRP Composite Laminate

Two different experimental techniques are employed to visualize the impact damage generated by a low-velocity impact on a carbon-fibre reinforced-polymer (CFRP) composite laminate. At the relatively low impact-velocity of 1.69 m.s−1, and a corresponding impact energy of 7.5 J, used in the present work the damage induced in the CFRP panel is barely visible to the naked eye but the techniques of ultrasonic C-scan and X-ray computed tomography (CT) can detect the damage that has occurred. This damage is mostly interlaminar damage, i.e. delaminations, between the plies due to a change in modulus from one ply to the next in the laminate. This interlaminar damage is usually accompanied by intralaminar damage, e.g. matrix cracking, in the ply itself. The type and extent of damage detected from using these two techniques is discussed and the relative merits of these techniques are compared. In general, the CT gave the better resolved picture of damage but the lateral extent of the damage was underestimated relative to C-scan which was more sensitive to very fine delamination cracks. In addition, a numerical approach, based on a finite-element analysis model, is employed to predict the type, location and extent of damage generated by the impact event and the modelling predictions are compared to the experimental results.

An improved composite impact damage model and bird-striking damage analysis with smoothed particle hydrodynamics-finite element method

An improved impact damage model is proposed, which can be used to analyze the progressive failure behavior of fiber-reinforced composites. The model is constructed based on the 3D Hashin failure criterion. However, the difference is that the strain component along the thickness direction in the matrix energy evolution model is introduced, and the effects of and on impact damage are added. Rigid-body and bird-body impact problems are studied, which validates the accuracy of the numerical model by comparison with experiments. A 3D numerical model of light aircraft fuel tank impact is constructed, and the SPH-FEM coupling method is used to predict the bird strike failure problem. The structural damage and impact behavior of a light aircraft fuel tank under impact loading are analyzed. The results show that, under different impact energies, the damage to the matrix is more serious and expands along the fiber direction, and the structure presents different damage forms. This paper provides an effective research model for the study of drop shock and the airworthiness of composite fuel tanks.

Validation of a DEM Model for predicting grain damage in an industrial-scale handling system

An industrial-scale handling system with a flight conveyor, a screw conveyor, and a rethresher as the core components was designed and built to validate a previously developed discrete-element-method-based (DEM) grain impact damage model. Corn and soybean samples were processed by the system at three impeller speeds and two feed rates, and the amount of damage caused by handling was evaluated. DEM simulations with the impact damage model were performed for the same test conditions. The experimental results showed that grain damage increased with increasing impeller speed and decreasing feed rate, which aligned with the simulation predictions. The damage fraction values estimated by the simulation were larger than the experimental measurements when the original DEM input parameters were used. The mean absolute error between the simulation and experimental results was 0.14 for the corn tests and 0.05 for the soybean tests. This overprediction may be because the particle-geometry coefficient of restitution (PG COR) was measured at low impact speeds but impact speeds in the validation system is high. The simulation predictions can be significantly improved by decreasing the PG COR from 0.75 to 0.55 for the corn and from 0.6 to 0.4 for the soybeans. The mean absolute error between the simulation and experimental results decreased from 0.14 to 0.02 for the corn tests and from 0.05 to 0.01 for the soybean tests after the reduction of PG COR. In addition, the sensitivity analysis suggested that the Young's modulus and particle shape contribute only minor changes to the damage fraction and the location of the damage for the conditions examined.

Rapid prediction of compression after impact properties of composite structures: An equivalent strategy for impact damage

Combined with the results of finite element simulation and experimental ultrasonic C-scan, a phenomenological-based equivalent impact damage finite element model was proposed and established to rapidly predict the damage evolution and buckling deformation of composite structures in compression after impact. An image recognition technology was adopted to divide the impact damage of composite laminates and stiffened panels into different regions, and a damage equivalent was conducted based on the measured impact damage size and morphology. Additionally, the material stiffness and strength parameters in different damage equivalent regions were reduced appropriately by different degrees. The impact pit deformation was equivalent to the element node offset in the corresponding area of the model, and the interface delamination and debonding were equivalent to the voids without elements. The equivalent impact damage model was applied to evaluate the buckling behavior and compressive strength after impact for laminates and stiffened panels using ABAQUS software. Moreover, a three-dimensional damage model considering the interaction of interlaminar delamination damage and interlaminar matrix and fiber damage was introduced to characterize the damage initiation, evolution, and extension behaviors of different damage modes. The comparative analysis indicated that the buckling and failure modes and compression after the impact strength simulated using the equivalent model were identical to the experimental results and had high correlation. This confirmed the accuracy, effectiveness, and applicability of the established equivalent impact damage model in predicting the compression buckling as well as residual strength and fracture modes for composite laminate and stiffened panel with simultaneous multi-zone impact damage.

Study on impact fatigue test and life prediction method of TC18 titanium alloy

To study the impact fatigue properties of TC18 titanium alloy and propose a new damage model for the impact fatigue life prediction of material, the impact fatigue test method and the impact response measurement scheme are designed. The impact fatigue tests are then implemented on a drop hammer impact test machine to obtain the fatigue lives and impact responses of the tested specimens under different impact conditions. A new impact damage model is proposed based on the theory of continuum damage mechanics considering the effect of strain rate. The calibration method of material parameters is presented, and the parameters of the impact damage model are obtained according to the test data of TC18. Afterward, the numerical implementation of impact damage calculation is established, and an ABAQUS user-defined subroutine is used to realize the finite element numerical simulation of impact fatigue damage accumulation. Finally, the damage evolution of TC18 under tensile impact fatigue loading is simulated and the corresponding fatigue life is predicted. The errors between the calculated impact fatigue lives and the experimental lives are less than 25%, which demonstrates the good validity and applicability of the proposed damage model and the numerical method.

Research on Rock Damage Evolution Based on Fractal Theory-Improved Dynamic Tensile-Compression Damage Model

According to the characteristics that the dynamic tension of rock material is elastic brittle and the dynamic compression is elastic plastic, based on previous studies, the influence of initial damage is considered in the established compression damage model, and the calculation formula of the damage threshold used to evaluate whether the surrounding rock is affected by blasting is given. According to the classic rock impact dynamic damage model and statistical damage mechanics theory, a rock compressive and tensile statistical damage constitutive model and impact damage model under blasting load is proposed. Based on the proposed damage model and the classic dynamic tensile damage model, the numerical simulation of blasting damage was carried out, and the numerical calculation results were compared with the field measurement results. Based on the established damage model, to further clarify the damage evolution characteristics of rock under blasting load, fractal dimension theory was introduced to analyze the rock damage under blasting loads with different blasting hole network parameters. The results show that compared with the axial direction of the blast hole, the direction of blast hole diameter is the main direction of blasting fracture extension. Tensile fracture mainly occurs along the hole diameter direction, and compression fracture mainly occurs below the hole bottom. Compared with the numerical calculation results based on the classical dynamic tensile damage model, the blasting fracture range obtained according to the damage model, especially the fracture depth below the bottom of the hole, was not much different from the measured value and was closest to the measured value. The crack density of 1 us, 90 aperture, and 130 aperture was larger than that of the other working conditions. Among them, the crack density of 130 aperture was the largest, followed by 90 aperture. At 2~3 us after initiation, cracks between two blast holes, radial cracks and circumferential cracks around two blast holes, and obvious cracks were formed around blastholes; at 4~5 us after initiation, the shock wave front decreased rapidly and propagated outward in the form of the compression wave. The crack propagation velocity was much smaller than that at 1~3 us after initiation. In summary, the proposed damage model is reasonable and has certain engineering practicability.

Impact damage modeling in woven composites with two-level Parametrically-Upscaled Continuum Damage Mechanics Models (PUCDM)

This paper develops two-level parametrically-upscaled continuum damage mechanics (PUCDM) models for woven composites. The PUCDM models are thermodynamically consistent, micro-/mesostructure-integrated constitutive models that bridge length scales through explicit incorporation of lower-scale descriptors into coefficients. The level-1 PUCDM model features homogenized intra-yarn constitutive response of unidirectional composite SERVEs, while the level-2 PUCDM model reflects the upscaled effect of mesostructural RVE response. The functional forms of the coefficients are established through machine learning algorithms operating on a micro-/mesostructural response database. The highly efficient two-level PUCDM models are validated using ballistic impact experiments on S-2 glass/SC-15 epoxy woven composite plates with good agreement.

Study of post-impact behaviour of thin carbon/epoxy laminates subject to fatigue tensile loading

This article concerns the experimental and numerical study of post-impact damage propagation in thin carbon/epoxy woven composite laminates loaded in fatigue tension. Low velocity normal drop weight impact tests are first performed. Post-impact fatigue tensile tests are then carried out. They are controlled in displacement. The monitoring is based on Digital Image Correlation and RX tomography. The influence of the impact energy and the tensile fatigue loading on the post-impact damage propagation is studied. The damage propagation is governed by matrix damage, with the emergence of tows/resin splittings and intra-tows crackings as well as delamination when the plies have different orientations. When the impact energy or the displacement level increases, the post-impact damage initiates sooner and propagate faster. In some cases, that can lead to a quasi-instantaneous failure identical to that observed for quasi-static tensile loading. The FEM based semi-continuous approach, initialy developped for the modelling of impact damage, is extended to fatigue loading for carbon/epoxy woven laminates. Fatigue damage laws, based on experimental observations are implemented. The modelling well correlates the experimental results in terms of damage propagation scenario and speed depending on the number of cycles for laminates made up of plies with the same orientation.

Modeling of Tunnel Concrete Lining under Fire and Explosion Damage

This paper presents studies that focus on fire and explosion‐induced damage of tunnel structures by employing the Discrete Element Method (DEM). By assuming a two‐dimensional aggregate distribution and reconstructing the digital representation of the experimental concrete blocks, a numerical model of the tunnel lining concrete was established in the PFC2D program. The temperature distribution and the shock wave pressure at the surface of the tunnel lining were obtained by using Fluent and LS‐Dyna separately; the final damage simulation of concrete section under different conditions was carried out in PFC2D. The results showed that PFC2D cooperatively provided more accurate and effective modeling and visualization of impact damage of concrete blocks. The visualizations of damage indicated the degree of damage more clearly and more intuitively. These findings also provide a potential method for further study of the damage assessment for entire tunnel lining structures.

Homogenized Modeling of Anisotropic Impact Damage in Rolled AZ31B with Aligned Second-Phase Particles

Magnesium is attractive for ballistic applications due to its high specific strength, but is not widely used due to its lower ductility as compared to other traditionally used materials (e.g. aluminum, titanium, and steel). Additionally, the behavior of magnesium is highly complex and is not well understood due to its HCP crystal structure and significant anisotropy. This work builds on direct numerical simulations (DNS) of rolled AZ31B magnesium with explicitly modeled second-phase particles subject to high strain rate uniaxial tension. The second-phase particles are preferentially aligned along the rolling direction, which induces anisotropies in void nucleation rates and void coalescence as a function of loading orientation. We propose a straightforward approach to account for these damage anisotropies in an anisotropic extension of the Gurson–Tvergaard–Needleman (GTN) homogenized damage model. The resulting anisotropic GTN model is calibrated against the uniaxial tension stress–strain responses predicted from DNS calculations for seven different loading orientations. The calibrated anisotropic GTN model is utilized to probe orientation effects in ballistic simulations. Two ballistic cases are conducted: (i) magnesium plate impacted with a steel sphere and (ii) magnesium plate impacted with a steel plate. The results quantify the degree to which preferential alignment of second-phase particles degrades the ballistic performance along the normal direction. This degradation is significant for a spherical impactor case, but fairly insensitive under plate impact. Consequently, the spall strength of rolled AZ31B is fairly insensitive to particle alignment.

Simplified modeling method of impact damage for numerical simulation of Lamb wave propagation in quasi-isotropic composite structures

In this paper, we present our investigation of impact damage modeling in a quasi-isotropic CFRP plate in which guided Lamb waves propagate. Because impact damages in CFRP structures consist of multiple microscopic damages, such as delamination, shear cracks, and transverse cracks, it is difficult to precisely model the impact damages for FEM analysis. However, in order to investigate the SHM systems to detect impact damages, we need to model various kinds of impact damages easily. Therefore, we attempt to establish a simple modeling method of impact damages. When the wavelength of a Lamb wave is much longer than the microscopic damages, we can assume the impact-damaged area as a homogeneous region with the stiffness degradation. The benefit of this model is to reduce the time to construct FEM models. In particular, we can easily set several damages in various positions of the structure.

Analysis of selected parameters in numerical modeling of low-velocity impact damage in composite structures

The barely visible impact damage (BVID) in layered composite structures is one of the critically important factors that affect structural residual life, when detected not early enough. This introduces a necessity of using numerical models for the prediction of the residual life of structures with BVID in order to reduce the number of experiments on real components and make it possible to predict various scenarios of BVID and the resulting structural residual life. Modeling of such a complex phenomenon is usually very challenging, and numerous factors and parameters should be taken into consideration in order to reflect the true damage form. In this study, the authors analyzed selected parameters of numerical modeling of this phenomenon.

Modeling and analysis of knee joint impact damage in triple jump manipulators based on finite element method

In order to study the three jump training and competition on knee joint impact damage degree, left knee joint of one healthy male athletes is used as the research object, a complete knee three-dimensional model was established based on the jumper’s knee CT scan and magnetic resonance imaging (MRI), including the femur, tibia, fibula, patella and knee major cartilage, ligaments. The multi-body dynamics analysis (MDA) and finite element analysis (FEA) method are used to calculate the three jump, jump starting, landing process of athletes knee joint impact, the state should change the status of stress, strain and displacement. The results show that in the three jump process, the load on the lateral contact area of the knee joint is the largest, the displacement is the largest, and it increases with the impact of jump and landing. This exacerbated the degree of wear and tear of the tibia, it tends to induce knee injury in athletes. The results show that the combination of finite element and MDA can better study the knee joint’s shock and vibration during the three-level jump training and competition, and these open up a new research method for the knee joint injury. It also provides a certain reference for the prevention and treatment of knee joint injury.

Development of an impact damage model for medium and large scale composite laminates using stacked-shell modeling: Verification and experimental validation

In the present work, the predictive capabilities of a Finite Element (FE) damage model developed for accurate and efficient analysis of medium to large scale structures are investigated. The proposed damage model is based on stacked sublaminate modeling approaches with cohesive interfaces. A pre-failure elastic response verification procedure is followed by model validation, performed by a Mode-I fracture toughness experimental campaign, from which the model predictive capabilities in interlaminar damage initiation and propagation are assessed. The analysis is then extended to the simulation of low velocity impact experiments found in the open literature, investigating the capabilities of the proposed model in intralaminar and interlaminar damage prediction. The results demonstrate the proposed methodology’s accuracy and efficiency in the simulation of laminated composites under static and impact conditions.

Study on Metal Plate Vibration Response Under Coal–Gangue Impact Based on 3D Simulation

The collision between the coal–gangue and the metal plate of the hydraulic support is a typical mechanical contact behavior in the surface coal mining, which will cause vibration in the tail beam and even in the whole hydraulic support. This paper presents a contact analysis of coal–gangue impact on the metal plate to discover how vibration signals are generated and propagated in the collision process. We build a dynamic model for rock impact on the metal plate based on the elastoplastic contact theory, the Drucker–Prager criterion and the Tavares and King particle impact damage model. We establish a finite element model of the impact system between the coal–gangue and the metal plate, conduct contact simulation using the software LS-DYNA and study the stress transfer process on the metal plate contact surface. We compare the parameters of coal and gangue impact on the metal plate and discuss how they are different by calculating the stress and displacement created in the metal plate, kinetic energy of the coal–gangue particles and the total energy of the metal plate. In addition, we study the effect of impact velocity on the vibration response of the metal plate. Results show that the stress wave diffuses outward from the center of the metal plate. The collision frequency, contact position of the rock sphere and re-collision time are random. As the impact velocity increases, the contact responses all increase. This study provides guidance for the analysis of vibration response of coal–gangue impact on tail beam .

Reprint of “Effects of asteroid property distributions on expected impact rates”

Assessments of the risk posed by asteroid impacts depend implicitly upon estimates of how frequently asteroids of different sizes and properties are expected to strike Earth. These impact rates are generally based upon populations of near-Earth objects as a function of absolute magnitude, which are then translated to equivalent size frequencies by assuming an average albedo. However, this simplified approach neglects the broad distribution of sizes and properties among objects of a given absolute magnitude. In this study, we use a probabilistic asteroid impact risk model to more rigorously investigate the effects of asteroid property distributions on estimated impact rates as a function of diameter, energy, mass, and blast damage radius. We also use impact damage modeling results to compare the effects of the new distribution-based results on expected casualty rates for two sample risk assessment cases. The current study focuses on mid-sized objects with diameters of 20–300m, which could cause substantial local ground damage but are unlikely to produce larger-scale regional or global effects. Particular emphasis is placed on sizes similar to the 1908 Tunguska event, which provides a unique source of evidence for such impacts and is often used as a reference point for damage potential and impact rates in the literature. Results demonstrate that accounting for realistic distributions of asteroid properties can significantly reduce expected impact intervals for these size ranges compared to estimates based on mean albedo, density, and velocity assumptions. These lower impact intervals, in turn, result in higher expected casualty estimates in impact risk assessment applications.

Effects of asteroid property distributions on expected impact rates

Assessments of the risk posed by asteroid impacts depend implicitly upon estimates of how frequently asteroids of different sizes and properties are expected to strike Earth. These impact rates are generally based upon populations of near-Earth objects as a function of absolute magnitude, which are then translated to equivalent size frequencies by assuming an average albedo. However, this simplified approach neglects the broad distribution of sizes and properties among objects of a given absolute magnitude. In this study, we use a probabilistic asteroid impact risk model to more rigorously investigate the effects of asteroid property distributions on estimated impact rates as a function of diameter, energy, mass, and blast damage radius. We also use impact damage modeling results to compare the effects of the new distribution-based results on expected casualty rates for two sample risk assessment cases. The current study focuses on mid-sized objects with diameters of 20–300 m, which could cause substantial local ground damage but are unlikely to produce larger-scale regional or global effects. Particular emphasis is placed on sizes similar to the 1908 Tunguska event, which provides a unique source of evidence for such impacts and is often used as a reference point for damage potential and impact rates in the literature. Results demonstrate that accounting for realistic distributions of asteroid properties can significantly reduce expected impact intervals for these size ranges compared to estimates based on mean albedo, density, and velocity assumptions. These lower impact intervals, in turn, result in higher expected casualty estimates in impact risk assessment applications.