Free Vibration Analysis and Design of an Adhesively Bonded Composite Single Lap Joint

2007 ◽  
Author(s):  
M. Kemal Apalak ◽  
Recep Ekici ◽  
Mustafa Yildirim
Keyword(s):  
Fiber Volume Fraction ◽  
Natural Frequencies ◽  
Volume Fraction ◽  
Plate Thickness ◽  
Mode Shapes ◽  
Lap Joint ◽  
Adhesively Bonded ◽  
Fiber Volume ◽  
Fiber Angle ◽  
Single Lap Joint

In this study the three dimensional vibration analysis of an adhesively bonded cantilevered composite single lap joint was carried out. The first four bending natural frequencies and mode shapes were considered. The back-propagation Artificial Neural Network (ANN) method was used to determine the effects of the fiber angle, fiber volume fraction, overlap length and plate thickness on the bending natural frequencies and the mode shapes of the adhesive joint. The bending natural frequencies and modal strain energies of the composite adhesive lap joint were calculated using the finite element method for random values of the fiber angle, the fiber volume fraction, the overlap length and the plate thickness. Later, the proposed neural network models were trained and tested with the training and testing data. The fiber angle was more dominant parameter than the fiber volume fraction on the natural bending frequencies and corresponding bending mode shapes, and the plate thickness and the overlap length were also important geometrical design parameters whereas the adhesive thickness had a minor effect. In addition, the present ANN models were combined with Genetic Algorithm to search a joint design satisfying maximum natural frequency and minimum modal strain energy conditions for each natural bending frequency and mode shape.

Free Bending Vibrations of Adhesively Bonded Orthotropic Plates With a Single Lap Joint

1996 ◽  
Vol 118 (1) ◽  
pp. 122-134 ◽  
Author(s):  
U. Yuceoglu ◽  
F. Toghi ◽  
O. Tekinalp
Keyword(s):  
Boundary Conditions ◽  
Natural Frequencies ◽  
Plate Theory ◽  
Mode Shapes ◽  
Mindlin Plate ◽  
Lap Joint ◽  
Orthotropic Plates ◽  
Adhesively Bonded ◽  
Bending Vibrations ◽  
Free Bending

This study is concerned with the free bending vibrations of two rectangular, orthotropic plates connected by an adhesively bonded lap joint. The influence of shear deformation and rotatory inertia in plates are taken into account in the equations according to the Mindlin plate theory. The effects of both thickness and shear deformations in the thin adhesive layer are included in the formulation. Plates are assumed to have simply supported boundary conditions at two opposite edges. However, any boundary conditions can be prescribed at the other two edges. First, equations of motion at the overlap region are derived. Then, a Levy-type solution for displacements and stress resultants are used to formulate the problem in terms of a system of first order ordinary differential equations. A revised version of the Transfer Matrix Method together with the boundary and continuity conditions are used to obtain the frequency equation of the system. The natural frequencies and corresponding mode shapes are obtained for identical and dissimilar adherends with different boundary conditions. The effects of some parameters on the natural frequencies are studied and plotted.

Natural frequencies of composite beams with a variable fiber volume fraction including rotary inertia and shear deformation

2009 ◽  
Vol 30 (6) ◽  
pp. 717-726 ◽  
Author(s):  
Y. Bedjilili ◽  
A. Tounsi ◽  
H. M. Berrabah ◽  
I. Mechab ◽  
E. A. Adda Bedia ◽  
...  
Keyword(s):  
Shear Deformation ◽  
Fiber Volume Fraction ◽  
Natural Frequencies ◽  
Volume Fraction ◽  
Composite Beams ◽  
Rotary Inertia ◽  
Fiber Volume

Forced Vibration Behavior of Adhesively Bonded Single-Lap Joint

2011 ◽  
Vol 110-116 ◽  
pp. 3611-3616 ◽  
Author(s):  
Xiao Cong He
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Forced Vibration ◽  
Natural Frequencies ◽  
Dynamic Test ◽  
Lap Joint ◽  
Adhesively Bonded ◽  
Element Analysis ◽  
Single Lap Joint ◽  
Vibration Behavior

This paper deals with forced vibration behavior of adhesively bonded single-lap joint theoretically and experimentally. The finite element analysis (FEA) software was used to predict the natural frequencies and frequency response functions (FRFs) of the joint. The dynamic test software and the data acquisition hardware were used in experimental measurement of the dynamic response of the joint. It is shown that the natural frequencies of the joint from experiment are lower than those predicted using finite element analysis. It is also found that the measued FRFs are close to the predicted FRFs for the first two modes of vibration of the joint. Above the second mode of vibration, there is considerable discrepancy between the measured and predicted FRFs.

Dynamic Optimization of Functionally Graded Thin-Walled Box Beams

2017 ◽  
Vol 17 (09) ◽  
pp. 1750109 ◽  
Author(s):  
Karam Y. Maalawi
Keyword(s):  
Fiber Volume Fraction ◽  
Natural Frequencies ◽  
Volume Fraction ◽  
Functionally Graded ◽  
Fiber Volume ◽  
Structural Dynamic ◽  
Design Variables ◽  
Target Values ◽  
Box Beams ◽  
Thin Walled

This paper introduces a mathematical model for optimizing the dynamic performance of thin-walled functionally graded box beams with closed cross-sections. The objective function is to maximize the natural frequencies and place them at their target values to avoid the occurrence of large amplitudes of vibration. The variables considered include fiber volume fraction, fiber orientation angle and ply thickness distributions. Various power-law expressions describing the distribution of the fiber volume fraction have been implemented, where the power exponent was taken as the main optimization variable. The mass of the beam is kept equal to that of a known reference beam. Side constraints are also imposed on the design variables in order to avoid having unacceptable optimal solutions. The mathematical formulation is carried out in dimensionless quantities, enabling the generalization to include models with different cross-sectional types and beam configurations. The optimization problem is solved by invoking the MatLab optimization ToolBox routines, along with structural dynamic analysis and eigenvalue calculation routines. A case study on the optimization of a cantilevered, single-cell spar beam made of carbon/epoxy composite is considered. The results for the basic case of uncoupled bending motion are given. Conspicuous design charts are developed, showing the optimum design trends for the mathematical models implemented in the study. It is concluded that the natural frequencies, even though expressed in implicit functions, are well-behaved, monotonic and can be treated as explicit functions in the design variables. Finally, the developed models can be suitably used in the global optimization of typical composite, functionally graded, thin-walled beam structures.

Free Vibration Analysis and Optimal Design of a Cantilevered Adhesively Bonded Composite Tubular Single Lap Joint

2007 ◽  
Vol 15 (6) ◽  
pp. 489-506 ◽  
Author(s):  
M. Kemal Apalak ◽  
Mustafa Yildirim
Keyword(s):  
Free Vibration ◽  
Natural Frequencies ◽  
Volume Fraction ◽  
Fibre Volume Fraction ◽  
Fibre Volume ◽  
Design Parameters ◽  
Lap Joint ◽  
Adhesively Bonded ◽  
Tube Radius ◽  
Fibre Angle

This study reports the most effective design parameters for the three-dimensional free vibration and modal stress state of an adhesively bonded cantilevered composite tubular single lap joint. The effects of fibre angle, fibre volume fraction, overlap length, tube thicknesses and inner tube radius on the first ten natural frequencies and mode shapes of the adhesive tubular joint were investigated, using the back-propagation Artificial Neural Network (ANN) method. In order to train and test the proposed artificial neural network models used to predict the first ten natural frequencies, as well as the corresponding modal strain energies, a series of free vibration and stress analyses was carried out. The finite element method was used for random values of the design parameters, such as the fibre angle, the fibre volume fraction, the overlap length, the tube thicknesses and the inner tube radius. The ANN models indicated that increasing each of all the design variables resulted in increases in the first ten natural frequencies as well as in the modal strain energies, whereas increasing the inner tube thickness reduced the natural frequencies but increased the modal strain energies. The fibre angles above 20° and the inner tube radius were more effective design parameters than the overlap length and the outer tube thickness. The Genetic Algorithm indicated completely different values of the design parameters of an optimal joint based on three objective functions, in which i) the natural frequency only was maximised, ii) the modal strain energy was minimised and iii) the previous objective functions were balanced. Thus all design parameters were maximised as possible except the inner tube thickness, and the fibre volume fraction became optimal at 70%.

Monitoring of mechanical properties of prestressed glass fiber epoxy composites over 12 months after fabrication

2021 ◽  
pp. 002199832110047
Author(s):  
Mahmoud Mohamed ◽  
Siddhartha Brahma ◽  
Haibin Ning ◽  
Selvum Pillay
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Flexural Strength ◽  
Compressive Residual Stress ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Epoxy Composites ◽  
Flexural Properties ◽  
Initial Increase ◽  
Fiber Volume

Fiber prestressing during matrix curing can significantly improve the mechanical properties of fiber-reinforced polymer composites. One primary reason behind this improvement is the generated compressive residual stress within the cured matrix, which impedes cracks initiation and propagation. However, the prestressing force might diminish progressively with time due to the creep of the compressed matrix and the relaxation of the tensioned fiber. As a result, the initial compressive residual stress and the acquired improvement in mechanical properties are prone to decline over time. Therefore, it is necessary to evaluate the mechanical properties of the prestressed composites as time proceeds. This study monitors the change in the tensile and flexural properties of unidirectional prestressed glass fiber reinforced epoxy composites over a period of 12 months after manufacturing. The composites were prepared using three different fiber volume fractions 25%, 30%, and 40%. The results of mechanical testing showed that the prestressed composites acquired an initial increase up to 29% in the tensile properties and up to 32% in the flexural properties compared to the non-prestressed counterparts. Throughout the 12 months of study, the initial increase in both tensile and flexural strength showed a progressive reduction. The loss ratio of the initial increase was observed to be inversely proportional to the fiber volume fraction. For the prestressed composites fabricated with 25%, 30%, and 40% fiber volume fraction, the initial increase in tensile and flexural strength dropped by 29%, 25%, and 17%, respectively and by 34%, 26%, and 21%, respectively at the end of the study. Approximately 50% of the total loss took place over the first month after the manufacture, while after the sixth month, the reduction in mechanical properties became insignificant. Tensile modulus started to show a very slight reduction after the fourth/sixth month, while the flexural modulus reduction was observed from the beginning. Although the prestressed composites displayed time-dependent losses, their long-term mechanical properties still outperformed the non-prestressed counterparts.

Sign in / Sign up

Export Citation Format

Share Document