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Experimental investigations on the mechanical responses of fully clamped circular plates with prefabricated crack at room temperature and low temperature have been conducted. Initial cracks with different lengths were prefabricated by the electrical discharge machining method. Low ambient temperature was created by the liquid nitrogen in a low-temp...
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Slender marine structures such as deep-water riser systems are continuously exposed to currents leading to vortex-induced vibrations (VIV) of the structure. This may result in amplified drag loads and fast accumulation of fatigue damage. Consequently, accurate prediction of VIV responses is of great importance for the safe design and operation of m...
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Citations
... Duan et al. [12] and Zeng et al. [13] investigated the behavior of circular aluminum alloy plates with initial small cracks to repeated mass impacts and the effect of the crack size (depth and length) on the impact response of the plate was discussed based on only the numerical and experimental results. They concluded that the effect of surface cracks on the structural response was considerable. ...
Offshore structures and ships can be progressively damaged due to repeated mass impacts induced by contacts with ships, ice floes, and dropped and/or floating other objects while in service. This paper aims to predict the residual deflection evolution of the marine structures under such impact repetitions. The side hull structures of the general ice-class vessels were selected for this study. The numerical simulations were performed to predict the deflection response of repeatedly impacted stiffened plates by using the software package Abaqus 6.13. For the simulations, the strain hardening of the relevant ice-class steel grade was adopted using the proposed constitutive equations, and the strain-rate hardening effects were taken into account by employing the existing formulations. The developed numerical model was substantiated against tests available in the open literature. Based on the validated model, a parametric study on various stiffened plates was performed. The evolution of the residual deflection of the repeatedly impacted plates with actual scantlings and various impact scenarios was investigated. A practical formula for the prediction of the residual deflection evolution of the plates under repeated mass impacts was proposed based on the regression analysis of the parametric study results. The reliability and accuracy of the proposed formula were confirmed through comparisons with numerical simulations and existing analytical formulations. It is expected that the proposed formula can be efficiently employed as a quick-hand tool for the reliable prediction of the residual deflection evolution incurred by repeated mass impacts.
... In those studies, the dynamic response and failure patterns of the aluminum beam/plate due to single impact loading that may diff er from actual impact scenarios, were explored. For the repeated impact loadings, although there are extensive investigations on the behavior of steel beams and plates [10][11][12][13][14][15][16][17][18][19][20][21][22], few studies for aluminum structures have been investigated yet [10,11,19,23]. Zhu and Faulkner [10] studied several repeated impact tests on mild steel and aluminum plates to investigate the response of the repeatedly impacted plates. ...
... Many studies have successfully adopted the numerical method in the assessment of structural responses to various loading conditions, especially for the repeated mass impacts problem, for example, Refs. [12][13][14][15][16][17][18][19][20][21][22]. ...
This paper presents a numerical investigation of the effects of impact location on the dynamic response of aluminum alloy plates to repeated mass impacts. The numerical model was developed and validated against relevant test data. In the simulation, the strain hardening was adopted using existing published equations. A parametric study was performed by considering different impact locations while keeping impact energy (mass and velocity) identically for each impact. The results showed that the plate was deformed progressively, and the resulting impact forces increased, while its duration decreased when the plate was impacted repeatedly. While changing in impact location after each impact remarkably affected the response of impacted plates, i.e., less damage was observed. The study results are expected to be helpful for the design of marine structures including fishing boats subjected to repeated impacts arising from collisions or dropped objects.
... Zhu et al. [4] carried out repeated-impact tests on stiffened plates and proposed a theoretical method based on inscribing and circumscribing a yield surface, which provided analytical predictions of the permanent deflection. Zeng et al. [5] conducted experiments on circular mild-steel plates with surface cracks suffering from repeated impacts at low temperatures, and the effects of low temperatures as well as surface cracks on the peak impact force and permanent deflection were determined. ...
The phenomenon of repeated impacts on engineering structures is very common, especially in naval and ocean engineering. When marine structures are subjected to repeated impact loadings, deformation and damage will accumulate as the impact number increases, resulting in the failure and damage of the structures, even causing serious accidents. Based on the rigid-plastic assumption, a theoretical model is established to analyze the plastic mechanical behavior of metal foam sandwich beams (MFSBs) suffering from repeated impacts, in which the membrane factor method (MFM) is applied to derive analytical solutions for the plastic responses of MFSBs. The theoretical predictions agree well with the results of impact tests and numerical simulations, indicating that the theoretical model is accurate and reliable. In addition, the dynamic responses of MFSBs are analyzed based on the MFM, and the effects of the core strength and the face thickness on the deflection responses are determined. The results show that the dimensionless permanent deflection of MFSBs is sensitive to the core strength ratio and the face thickness ratio, and as the core strength ratio or the face thickness ratio increases, the dimensionless permanent deflection decreases gradually in an exponential form. In addition, the influence of the core strength ratio and face thickness ratio becomes more significant as the impact number increases. The proposed theoretical method can provide a theoretical reference and technical support for the design of metal foam sandwich structures with improved impact resistance under repeated impact loadings.
... Based on this, it is clear that these crack present a danger to the structural integrity of the plate and they must be fixed to avoid failure. The behavior of cracked plates have received more attention by many modern researchers [4,5,6] and many studies have investigated the problem under different loads such as tensile loads [7,8,9] and thermal loads [10,11]. These studies employed multiple experimental, theoretical and numerical methods and one of the widest most used numerical method is the finite element method. ...
... The sheet patching will be of the same material welded to the rectangular plate via an adhesive bond at the location of the crack. The adhesive chosen for this study is an epoxy resign and was taken from a previous study [11,15] and its mechanical properties are shown in tables (2). Where d is the crack depth, L and t are the patch repair length and thickness respectively. ...
Aluminum sheet patching techniques can help to strengthen and fatigue crack repair in aluminum structures. This study focuses on the effect of using an aluminum sheet to repair a crack in an aluminum alloy plate. The sheet patching will be of the same material as the cracked plate and will be bonded to it using an adhesive layer. The cracked plate will be fixed on one end and have tension on the opposite side. Once the) ) Analysis of cracked aluminum plate repaired _______________________________ University Bulletin-ISSUE No.24-Vol. (4)-December-2022. 104 effect of using the patching for repair is determined, the geometrical parameters of the sheet patching will be investigated at different crack depths. The main objective of this paper is to study the equivalent stress and total deformation distribution across the plate, adhesive layer, and sheet patch. These studies will be conducted using a finite element simulation software known as ANSYS. Results show that using the sheet patching reduces the stresses and deformation developed around the crack significantly and that the geometrical properties of the sheet patching have a significant effect, especially at high crack depths; however, as the value of these parameters increases, the benefits gained from increasing them decreases.
... On the other hand, with the aid of experimental techniques and numerical tools, some efforts have been made to investigate the cold temperate effect on the repeated impact response (Cho et al. 2014;Truong et al. 2018a, b;Zeng et al. 2020). Results showed that the maximum values of the permanent deflection and the impact force varied with temperature, due to the changing mechanical properties of the structure material. ...
The repeated impact problem of a clamped elastic, strain-hardening plastic beam repeatedly impinged by a rigid heavy wedge with a low velocity at the mid-span is studied analytically and numerically. The beam motion is described using a Single-Degree-of-Freedom mass-spring model, governed by two structural parameters, i.e., structural resistance and the equivalent mass of beam. The explicit expressions of resistance functions of the beam during loading/unloading/reloading process are obtained from a series of simplified nonlinear quasi-static analysis with material strain hardening being taken into account. The equivalent mass of beam is related to the assumed transverse displacement profile of the beam which varies with its elastic–plastic state. Thereafter, the analytical solutions of the repeated impact response of beams made from the elastic-linear hardening (bi-linear) material are well validated by the detailed numerical simulations obtained by using ABAQUS/Explicit. Additional theoretical and numerical investigations with various tangent modulus values reveal that strain hardening can increase the elastic strain energy absorbed by the beam, but it has little influence on the duration of each impact.
... Shi [10,11] proposed an ideal elastic-plastic analytical method for predicting the deformation and the structural stiffness of rectangular plates and beams made of metal material under repeatedly uniform pressure loadings. Duan [12] and Zeng [13] investigated the mechanical behavior of aluminum alloy plates and mild steel plates with precast cracks under repeated drop weight impacts. ey showed that the initial crack reduced the energy absorption of thin plates and leaded plates become more sensitive with the increase in impact number. ...
Engineering structures in aviation and marine experience complex loads and are often affected by repeated impact loads. The damage accumulated from deflection in the process of repeated impact will often seriously affect the safety of the structure. In this research, the low-velocity repeated impacts behavior of corrugated core structures was investigated through experimental methods. A series of low-velocity repeated impact tests were carried out to study impact resistance, taking into account the effects of varied impact sites and impact energy levels and the effects of different impact locations and different levels of impact energy. It is also observed from the test that the upper panel played a crucial role and experienced the coupling mode of the local indentations and global bending deformations during the repeated impacts tests. Three different failure modes were observed when changing the impact energies and impact locations. Moreover, the “pseudo-shakedown” phenomenon was also found when the energy of the impacts is 10 J on the short span. The present surveys provide a reliable method and insight into the dynamic response of the aluminum corrugated core structures when subjected to low-velocity repeated impacts, which could be a significant guideline for the investigation and lightweight design of shipping and aviation.
... recently, the strength properties and buckling behaviour of cracked plates have received more attention by many researchers [8][9][10][11][12]. A number of studies have investigated the problem under tensile loads [13,14], thermal loads [15,16], and cyclic impact loading [16,17]. Over the years, many researchers were made the fairly comprehensive representation of the methods for tackling the cracked plate problems. ...
Purpose: In this paper, the bending strength and buckling stability of (AA 7075-T6) aluminium plate weakened by many transverse cracks, which located at different positions, subjected to concentrated loads applied at the ends were analysed. Design/methodology/approach: Numerical modelling and calculation by the finite element method (ANSYS Package), for the critical load of bending and compression panel were estimated. Findings: It found that the variation of the critical stress in bending and buckling is proportional to the crack conditions (no. of crack and location). In general, the critical load in bending and buckling decreases with increasing the crack number in structure. Research limitations/implications: For both bending and buckling, two transverse cracks on one face of plate is more stable than two transverse cracks on opposite faces. Practical implications: In addition, many experimental tests were carried out by using an INSTRON test machine to obtain the buckling critical loads, where the experimental results were compared with the ones of the finite element method. Furthermore, bending strength was calculated theoretically for the cracked panel. Originality/value: Comparison between the experimental and numerical (FE based model) data and between the theoretical and nu-merical (FE based model) data for buckling and bending strength respectively indicate the precise and the simplicity of the developed models to determine the critical loads in such cases.
