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FEM model of the Z-column with boundary conditions and composite structure after the thickness of the shell element.
Source publication
The study investigated short, thin-walled Z-shaped carbon–epoxy laminate columns. Z-columns were compressed while considering the eccentric force realized from the center of gravity of the column section. The study involved performing a nonlinear analysis of the structures with implemented geometric imperfections reflecting the first buckling modes...
Contexts in source publication
Context 1
... the developed numerical model of the column, a finite-element-type designated S8R was used, representing an 8-node element with a second-order shape function and reduced integration. In the case of the plates modeling the support planes of the column end sections, finite elements of type R3D4 were assumed, being rigid 4-node elements of type RIGID ( Figure 5). The FEM numerical analysis did not consider large displacements. ...
Context 2
... reference points used were those corresponding to the location of the centers of gravity of ball joints of the attachment heads, where simple support boundary conditions were defined. The two translational degrees of freedom (Ux = Uy = 0- Figure 5) and rotation about the column axis (URz = 0- Figure 5) were limited at the point reproducing the upper ball joint, while the three translational degrees of freedom (Ux = Uy = Uz= 0- Figure 5) and rotation (URz = 0- Figure 5) were limited at the reference point for the lower ball joint. Reference points were connected to rigid plates that support the ends of the columns by coupling all the degrees of freedom of the points and plates. ...
Context 3
... reference points used were those corresponding to the location of the centers of gravity of ball joints of the attachment heads, where simple support boundary conditions were defined. The two translational degrees of freedom (Ux = Uy = 0- Figure 5) and rotation about the column axis (URz = 0- Figure 5) were limited at the point reproducing the upper ball joint, while the three translational degrees of freedom (Ux = Uy = Uz= 0- Figure 5) and rotation (URz = 0- Figure 5) were limited at the reference point for the lower ball joint. Reference points were connected to rigid plates that support the ends of the columns by coupling all the degrees of freedom of the points and plates. ...
Context 4
... reference points used were those corresponding to the location of the centers of gravity of ball joints of the attachment heads, where simple support boundary conditions were defined. The two translational degrees of freedom (Ux = Uy = 0- Figure 5) and rotation about the column axis (URz = 0- Figure 5) were limited at the point reproducing the upper ball joint, while the three translational degrees of freedom (Ux = Uy = Uz= 0- Figure 5) and rotation (URz = 0- Figure 5) were limited at the reference point for the lower ball joint. Reference points were connected to rigid plates that support the ends of the columns by coupling all the degrees of freedom of the points and plates. ...
Context 5
... reference points used were those corresponding to the location of the centers of gravity of ball joints of the attachment heads, where simple support boundary conditions were defined. The two translational degrees of freedom (Ux = Uy = 0- Figure 5) and rotation about the column axis (URz = 0- Figure 5) were limited at the point reproducing the upper ball joint, while the three translational degrees of freedom (Ux = Uy = Uz= 0- Figure 5) and rotation (URz = 0- Figure 5) were limited at the reference point for the lower ball joint. Reference points were connected to rigid plates that support the ends of the columns by coupling all the degrees of freedom of the points and plates. ...
Citations
... In some works, the stiffness of the contact layer is not mentioned in detail in the modelling. It is then stated that the contact has been modelled in a standard way in the relevant software [36,37,38]. ...
The paper deals with the modelling of multi-bolted connections under preload conditions in a systemic approach. A modelling procedure based on the finite element method is presented. According to it, the connection was treated as a combination of four subsystems: a bolt-nut set, a pair of joined components and a contact layer between them. The contact layer model used allows the actual mechanical properties of the contact joint to be taken into account. The application of the method is illustrated using the example of an asymmetric connection. First, its solid model was built, followed by a discrete model in which the bolt-nut set was replaced by a hybrid model with a non-deformable bolt head and nut and a deformable bolt shank. Finally, selected results of connection calculations are also provided. The utilitarian relevance of a systemic approach to modelling multi-bolted connections and the opportunities it delivers for connection assessment is presented.
... similarly, the same is true for the next FeM software, Midas NFX. in this case also, the constant normal and tangential stiffness coefficients as well as the friction coefficient are inserted [34,35]. in some papers, the stiffness of the contact layer is not mentioned in detail in the modelling. an information is then provided that the contact has been modelled in a standard way in the respective software [36][37][38][39]. ...
The subject of the paper is the modelling of multi-bolted connections that are at the pretensioning stage. Taking a systematic approach to the modelling issue, the connection was treated as a composite of four subsystems: a bolt set, a pair of joined elements and a contact layer between them. The first part of the paper describes experimental studies to determine the contact stiffness of a pair of elements separated from an exemplary asymmetric multi-bolted connection. The normal loading and unloading direction of the contact joint was considered. The tests were performed with the use of an INSTRON 8850 servo-hydraulic testing machine equipped with an extensometer. A normal stiffness characteristic in the form of an exponential function was proposed for the tested contact joint. It will be applied in the second part of the paper, in which finite element modelling of the multi-bolted connection will be presented.
... In view of such a wide spectrum of applications, these structures can be subjected to different types of impacts, i.e. mechanical, chemical but also thermal loading, which is the focus of this paper. The influence of temperature can therefore be crucial for some structures and lead to effects such as: loss of stability [10][11][12][13], material degradation [14,15], degradation of elastic constants, delamination [14,[16][17][18], reinforcement slippage, creep, thermal flow. It is also worth mentioning that already during the manufacturing process, composites are subjected to increased temperatures [19], and then cooled to ambient temperature, which can lead to residual stresses in the material [20]. ...
This study investigates the influence of temperature variations on the buckling properties of thin-walled omega-profiles fabricated from carbon-epoxy composite materials. Utilizing a MTS testing machine, compression tests were
conducted on these profiles at temperatures ranging from -20°C to 80°C, in 20°C increments. The primary objective
was to assess how temperature fluctuations impact the buckling load and load-bearing capacity of these composite
profiles under axial compression. The experimental setup allowed for precise measurement of load-displacement
and load-deflection characteristics, and the critical load at which buckling initiation occurred. Observations revealed
that the buckling resistance of the profiles exhibited a complex dependence on temperature. At lower temperatures,
the composite material demonstrated enhanced stiffness and strength, marginally increasing buckling resistance.
Conversely, at elevated temperatures, a noticeable degradation in mechanical properties was observed, leading to
a reduced buckling load and altered failure modes. To complement the experimental findings, a comprehensive
finite element (FE) analysis was conducted for sample in room temperature. The FE model, developed to replicate
the experimental conditions closely, employed an eigenvalue-based approach to predict the buckling initiation and
progression accurately. The presented results are the results of only preliminary tests and they will be expand about
more samples number as well as to determine material properties for various temperatures.
... The plate was made of laminate, which was a stack of eight layers in a symmetrical position of the layers with respect to the composite's center plane with a total thickness of 1.048 mm (each individual layer had a thickness of 0.131 mm) [42,43]. The arrangement of the composite layers was adopted from the literature [44]. It represented a popular laminate configuration in the form of: [0/90/0/90]s. ...
... The analysis of these signals could accurately monitor the health of the composite laminates and ensure their safety. P. Wysmulski et al. proposed a new method for determining initial failure inside CFRP columns based on AE technology [21]. By analyzing the amplitude of the AE signal, corresponding to the load time curve, the load where the initial damage occurs can be effectively obtained. ...
Carbon-fiber-reinforced polymer (CFRP) composites are widely used in lightweight structures because of their high specific strength, specific modulus, and low coefficient of thermal expansion. Additionally, the unidirectionally arrayed chopped strand (UACS) laminates have excellent mechanical properties and flowability, making them suitable for fabricating structures with complex geometry. In this paper, the damage process of UACS quasi-isotropic laminates under tensile load was tested using acoustic emission detection technology. The mechanical properties and damage failure mechanism of UACS laminates were studied combined with finite element calculation. By comparing and analyzing the characteristic parameters of acoustic emission signals such as amplitude, relative energy, and impact event, it is found that acoustic emission behavior can accurately describe the damage evolution of specimens during loading. The results show that the high-amplitude signals representing fiber fracture in continuous fiber laminates are concentrated in the last 41%, while in UACS laminates they are concentrated in the last 30%. In UACS laminates, more of the damage is caused by matrix cracks and delamination with medium- and low-amplitude signals, which indicates that UACS laminates have a good suppression effect on damage propagation. The stress–strain curves obtained from finite element analysis agree well with the experiment results, showing the same damage sequence, which confirms that the model described in this research is reliable.
... Composite laminates are widely used in aerospace, automotive, shipbuilding, and other fields due to their high strength, high stiffness, and better fatigue resistance [1][2][3][4][5]. However, composite materials are very sensitive to low-velocity impacts; under a lowvelocity impact, composite materials will produce large internal delamination (delamination, matrix cracking, fiber bundle separation, fiber breakage, etc.), while only leaving a small indentation on the impact surface. ...
A comparative experimental and numerical study of the impact behaviour of carbon-fiber-reinforced thermoplastic (TP) and thermoset (TS) composites has been carried out. On the one hand, low velocity impact (LVI) tests were performed on TP and TS composites with different lay-up sequences at different energy levels, and the damage modes and microscopic damage mechanisms after impact were investigated using macroscale inspection, C-scan inspection, and X-ray-computed tomography. The comparative results show that the initial damage valve force under LVI depends not only on the material, but also on the layup sequence. The initial valve force of the P2 soft layer with lower stiffness is about 11% lower than that of the P1 quasi-isotropic layer under the same material, while the initial valve force of thermoplastic composites is about 28% lower than that of thermoset composites under the same stacking order. Under the same stacking order and impact energy level, the damage area and depth of TP composites are smaller than those of TS composites; while under the same material and impact energy level, the indentation depth of P2 plies is greater than that of P1 plies, and the damage area of P2 plies is smaller than that of P1 plies, but the change of thermoplastic composites is not as obvious as that of thermoset composites. This indicates that TP composites have a higher initial damage threshold energy and impact resistance at the same lay-up order, while increasing the lay-up ratio of the same material by 45° improves the impact resistance of the structure. In addition, a damage model based on continuum damage mechanics (CDM) was developed to predict different damage modes of thermoplastic composites during low velocity impact, and the analytical results were compared with the experimental results. At an impact energy of 4.45 J/mm, the error of the initial damage valve force is 5.26% and the error of the maximum impact force is 4.36%. The simulated impact energy and impact velocity curves agree with the experimental results, indicating that the finite element model has good reliability.
... For this reason, it becomes reasonable to extend the research to include a Table 1. Laminate layout [51]. ...
This paper investigates the effect of an open hole on the stability of a compressed laminated composite plate. The study was carried out in two ways: using experimental tests and numerical analysis. As a result of the experiment, the buckling form and path of the plate were recorded. The form of buckling was determined using the ARAMIS non-contact measurement system. The critical load value was determined from the working path using the approximation method. The experimental results were verified by numerical analysis based on the finite element method. FEM investigations were carried out in terms of a linear eigenproblem analysis. This allowed the bifurcation load and the corresponding buckling form of the numerical model of the plate to be determined. Investigating the effect of the hole in the compressed plate at a critical state showed high agreement between the proposed test methods. No clear effect of the hole size on the buckling of the plate was observed. In contrast, a clear effect of the hole on the critical load value was determined. The maximum decrease in the critical load value was 14%. The same decrease was observed for the stiffness of the post-critical characteristics. It was shown that the [45|−45|90|0]s composite plate had more than three times lower strength compared to [0|−45|45|90]s and [0|90|0|90]s. The novelty of this article is the development of a research methodology based on new interdisciplinary research methods for describing the influence of the central hole on the stability of compressed composite plates. The ABAQUS system was used for the numerical analysis.
... Over the past three decades, in studies regarding the compressive fracture of unidirectional composites [14][15][16][17][18][19], several types of possible failure modes, such as the Euler buckling or macrobuckling of the specimen, the crushing of the specimen end, longitudinal splitting, interfacial failure, the elastic microbuckling of fibers, the plastic microbuckling of fibers in a kinking mode, and the shear failure of the specimen, have been observed and reported [13]. Among all failure modes, the fiber microbuckling failure mode is recognized as the dominant compressive failure mechanism [20]. ...
... According to this criterion, the equivalent plastic strain at the onset of damage is described as a function of the stress triaxiality and strain rate, as illustrated in Figure 3b. Additionally, to consider the interfacial failure between the fiber and the resin, a cohesive element was introduced to model the interfacial behavior and strength [18,19]. The cohesive element is defined using the traction separation law under the mixed mode, as shown in Fig The traction separation behavior is defined by associating the traction, which acts on the node between the resin and fiber, with the distance between them. ...
... The shear fracture strength of the interface and the mode II fracture toughness ( ), which is an indicator of material resistance, are presented in Table 3. Additionally, to consider the interfacial failure between the fiber and the resin, a cohesive element was introduced to model the interfacial behavior and strength [18,19]. The cohesive element is defined using the traction separation law under the mixed mode, as shown in Figure 4. Additionally, to consider the interfacial failure between the fiber and the resin, a cohesive element was introduced to model the interfacial behavior and strength [18,19]. ...
Compressive strength is one of the most important properties of carbon fiber reinforced plastics (CFRP). In this study, a new method for predicting the axial compressive strength of CFRP using the response surface method is developed. We focused on a microbuckling model to predict the compressive strength of unidirectional fiber composites. For the microbuckling model, axial shear properties are required. To obtain the compressive strength for various material properties, we perform individual shear tests and numerical simulations, but these require enormous computational costs and extended time. To address the issue of computational cost, in this study, we propose a new method to predict compressive strength using the response surface method. First, we perform shear simulation in a microscale fracture model for unidirectional CFRP with various parameters of the fiber and resin properties. Based on the results of the shear simulation, the response surface method is used to evaluate and develop prediction equations for the shear properties. This method allows for the study of the objective values of the parameters, without significant computational effort. By comparing both the results predicted from the response surface method (RSM) and the simulation results, we verify the reliability of the prediction equation. As a result, the coefficient of determination was higher than 94%, and the validity of the prediction method for the compressive strength of CFRP using the response surface method (RSM) developed in this study was confirmed. Additionally, we discuss the material properties that affect the compressive strength of composites comprised of fibers and resin. As a result, we rank the parameters as follows: fiber content, elastic modulus after resin yield, yield stress, and initial elastic modulus.
... Standardised bolt sets are most commonly used to create bolted connections for which preloading is required [1][2][3]. They are used to join not only steel, but also composite [4,5] or additively manufactured [6,7] components. Among the most advanced sets are HV high-strength bolt sets [8], which can be used in a wide range of structures exposed to various, including aggressive, environmental conditions. ...
The aim of this article is to investigate the effect of atmospheric conditions on the tightening behaviour of HV bolts in structural bolt sets. The article describes the results of experimental tests carried out for bolt sets of a selected type. The parts of the joined sets were stored according to the specified six different conditions for four weeks before assembly. Paper, cardboard boxes and anticorrosion foils were used as protection against atmospheric conditions. The behaviour of unassembled and assembled bolt sets was also taken into account. The variation in the friction coefficient depending on the clamping force and storage conditions of the bolt sets was demonstrated. This applies both to the contact between the joining elements on the threaded surfaces and to the area between the bolt head and the bearing surface of the nut and washer.
... Previous studies on composite structures predominantly concerned analytical and numerical analyses of structures with standard cross sections under simple loads. These considerations Numerical and Experimental Study of Crack Propagation in the Tensile Composite Plate with the Open Hole have only been verified to a limited extent by experimental tests carried out on actual structural components [13][14][15]. ...
In this study, the thin-walled plate with the central open hole made of carbon-epoxy composite was investigated. The plate was tested in tension to investigate the mechanism of crack formation in the composite structure. The studies were carried out using two individual methods: experimental and numerical. In the experiment test, load was measured as the function of plate elongation. The Plate elongation was analysed using the Aramis optical non-contact measurement system. In the numerical study, the FEM model reproducing the experimental conditions was developed in the Abaqus software. The cracking process was modelled using the XFEM method (extended finite element method). This procedure allowed the of the composite to be examined over the full range of the tensile load. The behaviour of the plate with a circular open hole was investigated before damage symptoms and the damage initiation load was determined. The study continued to analyse the initial cracking and delamination of the laminate layers, together with crack propagation leading to cracking of all the laminate layers (complete failure of the composite structure). The novelty of this study is that it uses the popular XFEM method to describe the cracking and failure of the composite structure. In addition, the study proposes the novel method for determining the crack initiation and failure loads of the composite plate under tension, and the results obtained thereby are verified numerically.
