Bai Ruixiang

Study on failure process of delaminated stiffened composite plates under compression

Failure behavior of the delaminated stiffened composite plates under compression is studied by the finite element method, based on a Global-Local variational model. A virtual crack closure technique and a self-adaptive grid moving scheme are proposed to predict the delamination growth process. The contact effect along the delamination front is considered. The numerical results show that the influences of the distribution and location of the stiffeners, the configuration and size of the delamination, the boundary condition and the contact upon the failure behavior of the plates are significant.

Numerical analysis of delamination growth for stiffened composite laminated plates

A study of postbuckling and delamination propagation behavior in delaminated stiffened composite plates was presented. A methodology was proposed for simulating the multi-failure responses, such as initial and postbuckling, delamination onset and propagation, etc. A finite element analysis was conducted on the basis of the Mindlin first order shear effect theory and the von-Kármán nonlinear deformation assumption. The total energy release rate used as the criteria of delamination growth was estimated with virtual crack closure technique (VCCT). A self-adaptive grid moving technology was adopted to model the delamination growth process. Moreover, the contact effect along delamination front was also considered during the numerical simulation process. By some numerical examples, the influence of distribution and location of stiffener, configuration and size of the delamination, boundary condition and contact effect upon the delamination growth behavior of the stiffened composite plates were investigated. The method and numerical conclusion provided should be of great value to engineers dealing with composite structures.

Numerical Analysis for the Interlayer Toughening of Piezoelectric Smart Composite Plate

The piezoelectric composite material could engender stress concentration resulting from small cracks during layers easily, as the cracks growth will lead to the failure of the whole structure. In this paper, a finite element model for piezoelectric composite materials by ABAQUS including interlayer crack was established, and the J integral and crack tip stress of different types PZT patches were calculated by using the equivalent integral method. Then, the J integral for adhesive layers with different thickness, elastic modulus considering and not considering piezoelectricity was investigated. The results show that the J integral of mode I, II reduces with thicker adhesive layer and lower elastic modules, and the J integral of mode II decreases more sharply than that of mode I.

Numerical Analysis of Buckling and Delamination Growth for Stiffened Composite Laminated Plates with Piezoelectric Actuators

The buckling and delamination propagation behavior in delaminated piezoelectric stiffened composite plates subjected to combined applied voltage and compressive loading are studied. The cohesive element for the non-linear finite element software ABAQUS is used to simulate the interface of the delamination region in the composite plates. The numerical simulation is conducted by using piezoelectric solid element and conventional shell element. The delamination propagation and the failure of stiffened composite plates are predicted by strength-based and energy-based criteria. The bucking control effect for the different buckling of piezoelectric stiffened composite plates with applied voltage was investigated, and the delamination propagation behavior of stiffened composite plates with piezoelectric actuators was studied. The results obtained by numerical analysis indicate that the appropriate control by piezoelectric actuators can retard local buckling of delaminated sub-laminates and prevent delamination growth effectively.

Notice of Retraction Stability of hollow constructions repaired with carbon fiber-reinforced polymer

The buckling investigation of hollow cylinder constructions by carbon fiber reinforced polymer laminates subjected to axial compression load was explored adopting finite element method and analytical methods. The finite element model of simulating repair was established for hollow damage cylinder with carbon fiber-reinforced polymer laminates under ideal bonding condition by constraint equations. The analytical formula of buckling loads for hollow cylinder with CFRP under compression load was also derived based on energy theory. The finite element results approximately coincide with the analytical formula by numerical examples. The effect upon increasing the buckling load of hollow construction is remarkable by bonding CFRP and improving the CFRP layer parameters also can raise the buckling load. The results show the proposed design approach is conservative and acceptable.

Finite Element Analysis of Vibration of Concrete Beam Reinforced with Fiber Composite Laminates

The frequencies of concrete beam strengthened with fiber-reinforced polymer have been studied by using finite element method. Based on Mindlin shear deformation theory, the mass matrix and the stiffness matrix of concrete beam, adhesive element and composite laminates have been constructed. By typical numerical results, the natural frequencies of free vibration for concrete beam reinforced with FRP have been achieved and the method used in this paper will provide a reference for study dynamic characteristics of concrete structures strengthened by FRP.

Delamination Growth of Foam Core Composite Sandwich Plate under Harmonic Dynamic Load

In this paper, the delamination growth of sandwich plate with foam core and composite sheets under harmonic dynamic load is investigated by finite element method. The composite sheet is modeled as layered shell element considering first order shear effect, and the foam core is modeled as isotropic solid element; while for the bond line between sheet and core is simulated by using simple cohesive layer models with a bilinear constitutive relationship. Reference to previous experience, the most significant parameter GC is applied to tracing delamination growth. By some numerical examples, the behavior of dynamic delamination growth of sandwich plates is investigated.