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Cantilever Beam (cantilever + beam)
Selected AbstractsDamage identification of structures with uncertain frequency and mode shape dataEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 5 2002Yong Xia Abstract A statistical method with combined uncertain frequency and mode shape data for structural damage identification is proposed. By comparing the measured vibration data before damage or analytical finite element model of the intact structure with those measured after damage, the finite element model is updated so that its vibration characteristic changes are equal to the changes in the measured data as closely as possible. The effects of uncertainties in both the measured vibration data and finite element model are considered as random variables in model updating. The statistical variations of the updated finite element model are derived with perturbation method and Monte Carlo technique. The probabilities of damage existence in the structural members are then defined. The proposed method is applied to a laboratory tested steel cantilever beam and frame structure. The results show that all the damages are identified correctly with high probabilities of damage existence. Discussions are also made on the applicability of the method when no measurement data of intact structure are available. Copyright © 2002 John Wiley & Sons, Ltd. [source] Fracture and fatigue study of unidirectional glass/epoxy laminate under different mode of loadingFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 5 2010M. KENANE ABSTRACT Interlaminar fracture is the dominant failure mechanism in most advanced composite materials. The delaminating behaviour of materials is quantified in terms of the strain energy release rate,G. In this paper, the experimental measurements of the fatigue delaminating growth for some combinations of energy release rate mode ratio have been carried out on unidirectional glass/epoxy laminates. On this base the constants in the Paris equation have been determined for each GII/GT considered modal ratio. The fatigue threshold strain energy release rate ,,GTth, below which delaminating doesn't occur, were measured. Three type specimens were tested, namely: double cantilever beam (DCB), end-loaded split (ELS) and mixed-mode bending (MMB) under mode I, mode II and mixed-mode (I + II) loading, respectively. Scanning electron microscopy techniques were used to identify the fatigue delamination growth mechanisms and to define the differences between the various modes of fracture. [source] Suppressing local particle oscillations in the Hamiltonian particle method for elasticityINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 12 2010Masahiro Kondo Abstract The governing equation of elasticity is discretized into motion equations of the particles in a Hamiltonian system. A weighted least-square method is adopted to evaluate the Green,Lagrange strain. Using a symplectic scheme for the Hamiltonian system, we obtain the property of energy conservation in the discretized calculations. However, local particle oscillations occur, and they excessively decrease low frequency motion. In this study, we propose the use of an artificial potential force to suppress the local oscillations. The accuracy of the model with and without the inclusion of the artificial force is examined by analyzing a cantilever beam and wave propagation. With the inclusion of the artificial force, the local oscillations are reduced while energy conservation is maintained. Copyright © 2009 John Wiley & Sons, Ltd. [source] On the L2 and the H1 couplings for an overlapping domain decomposition method using Lagrange multipliersINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 3 2007P.-A. Guidault Abstract In this paper, a comparison of the L2 and the H1 couplings is made for an overlapping domain decomposition method using Lagrange multipliers. The analysis of the local equations arising from the formulation of the coupling of two mechanical models shows that continuous weight functions are required for the L2 coupling term whereas both discontinuous and continuous weight functions can be used for the H1 coupling. The choice of the Lagrange multiplier space is discussed and numerically studied. The paper ends with some numerical examples of an end-loaded cantilever beam and a cracked plate under tension and shear. It is shown that the continuity enforced with the H1 coupling leads to a link with a flexibility that can be beneficial for coupling a very coarse mesh with a very fine one. To limit the effect of the volume coupling on the global response, a narrow coupling zone is recommended. In this case, volume coupling tends to a surface coupling, especially with a L2 coupling. Copyright © 2006 John Wiley & Sons, Ltd. [source] Fully coupled non-linear analysis of piezoelectric solids involving domain switchingINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 1 2003Wenjun Zeng Abstract Domain switching is the cause of significant non-linearity in the response of piezoelectric materials to mechanical and electrical effects. In this paper, the response of piezoelectric solids is formulated by coupling thermal, electrical, and mechanical effects. The constitutive equations are non-linear. Moreover, due to the domain switching phenomenon, the resulting governing equations become highly non-linear. The corresponding non-linear finite element equations are derived and solved by using an incremental technique. The developed formulation is first verified against a number of benchmark problems for which a closed-form solution exists. Next, a cantilever beam made of PZT-4 is studied to evaluate the effect of domain switching on the overall force,displacement response of the beam. A number of interesting observations are made with respect to the extent of non-linearity and its progressive spread as the load on the beam increases. Copyright © 2002 John Wiley & Sons, Ltd. [source] STIFFNESS OF COMPRESSION TESTING MACHINESJOURNAL OF TEXTURE STUDIES, Issue 2 2000HARALD ROHM ABSTRACT A ring test with six participating laboratories and rubber stoppers as reference material was performed to monitor the performance of commercial compression testing instruments. Testing conditions were chosen to be in the range of regular compression testing. Small, single screw instruments with a cantilever exhibited a significant deviation in the force/deformation-response compared with double-screw instruments with a crosshead. Additional tests made with an external device for displacement recording revealed that these differences have to be attributed to insufficient stiffness and some compliance in the cantilever of the tested single-screw instruments. Some consequences of the test results for experiments on soft, semi-soft and rigid food materials are discussed and an equation is developed to correct for the flexing of the cantilever beam in the single screw machine. [source] Optimal multi-interval control of a cantilever beam by a recursive control algorithmOPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 4 2009Chun-Hung Lin Abstract The optimal-distributed control of a transversely vibrating cantilever beam is studied with the objective of minimizing the deflection and velocity in a given period of time with the minimum possible expenditure of force. The beam undergoes transient vibrations and is subject to given displacement and velocity initial conditions. The control is exercised by means of a transversely distributed force referred to as the control force. In the present study, a multi-interval optimal control method is developed with the application of a maximum principle. The method consists of dividing the control duration into several intervals and using the maximum principle to obtain the optimality conditions at each interval. The explicit solutions for a cantilever beam are obtained by a recursive algorithm that takes the final conditions of the last interval as the initial conditions of the next interval. The formulation and the method of solution are suitable and convenient for digital computation. Numerical results are given, which compare the deflections, velocities and the control force under the optimal multi-interval control with those under the optimal single-interval control. Copyright © 2008 John Wiley & Sons, Ltd. [source] Structure,properties relations in titanium-based thermoplastic fiber,metal laminatesPOLYMER COMPOSITES, Issue 3 2006P. Cortés This paper investigates the interfacial, tensile, and fatigue properties of a titanium alloy fiber,metal laminate (Ti-FML) based on woven glass-fiber-reinforced polyetherimide (GF/PEI). Initial tests, using the single cantilever beam (SCB) geometry have shown that it is not necessary to surface treat the titanium alloy in order to achieve a high value of metal,composite interfacial fracture toughness. Tensile tests have shown that the mechanical properties of the FML lie between those offered by its constituent materials. Tension,tension fatigue tests have shown that the fatigue lives of these laminates are superior to those offered by the plain titanium alloy. The mechanical properties of this glass fiber/PEI FML have also been compared with those offered by an FML based on a unidirectional carbon-fiber-reinforced polyetheretherketone (CF/PEEK) composite. Here, it has been shown that although the fatigue properties of this woven GF/PEI composite are inferior to those of the CF/PEEK FML, they do offer a higher temperature capability due to the higher glass transition temperature of the PEI matrix. Polym. Compos. 27:264,270, 2006. © 2006 Society of Plastics Engineers. [source] Fracture behavior of polyetherimide (PEI) and interlaminar fracture of CF/PEI laminates at elevated temperaturesPOLYMER COMPOSITES, Issue 1 2005Ki-Young Kim To investigate the effects of environmental temperature on fracture behavior of a polyetherimide (PEI) thermoplastic polymer and its carbon fiber (CF/PEI) composite, experimental and numerical studies were performed on compact tension (CT) and double cantilever beam (DCB) specimens under mode-I loading. The numerical analyses were based on 2-D large deformation finite element analyses (FEA). Elevated temperatures greatly released the crack tip triaxiality (constraint) and promoted matrix deformation due to low yield strength and enhanced ductility of the PEI matrix, which resulted in the greater plane-strain fracture toughness of the bulk PEI polymer and the interlaminar fracture toughness of its composite during delamination propagation with increasing temperature. Furthermore, the high triaxiality was developed around the delamination front tip in the DCB specimen, which accounted for the poor translation of matrix toughness to the interlaminar fracture toughness by suppressing the matrix deformation and reducing the plastic energy dissipated in the plastic zone. Especially, at delamination initiation, the weakened fiber/matrix adhesion at elevated temperatures led to premature failure of fiber/matrix interface, suppressing matrix deformation and preventing the full utilization of matrix toughness. Consequently, low interlaminar fracture toughness was obtained at elevated temperatures. POLYM. COMPOS., 26:20,28, 2005. © 2004 Society of Plastics Engineers. [source] | |||||||||||||