scholarly journals Analysis of Local Delamination in A Cracked Composite Laminate Loaded in Tension

1993 ◽  
Vol 2 (6) ◽  
pp. 096369359300200
Author(s):  
J. Zhang ◽  
C. Soutis
Keyword(s):  
Composite Laminate ◽  
Crack Density ◽  
Strain Energy Release ◽  
Matrix Crack ◽  
Total Strain Energy ◽  
Element Analysis ◽  
The Matrix ◽  
Dimensional Finite Element ◽  
Elastic Fracture ◽  
Good Agreement

In the present paper the total strain energy release rate G associated with delaminations that initiate from a matrix crack in a [±θm/90n]s composite laminate is calculated using the potential energy approach in elastic fracture mechanics. The predictions are compared with a two-dimensional finite element analysis. It is found that for delamination lengths greater than two-ply thicknesses the theoretical and numerical results are in good agreement. The new model shows that G is affected by the matrix crack density and residual hygrothermal stresses.

scholarly journals Output decoupling property of planar flexure-based compliant mechanisms with symmetric configuration

2016 ◽  
Vol 7 (1) ◽  
pp. 49-59 ◽  
Author(s):  
Y. S. Du ◽  
T. M. Li ◽  
Y. Jiang ◽  
J. L. Zhang
Keyword(s):  
Analytical Model ◽  
Compliant Mechanisms ◽  
Element Analysis ◽  
Modeling Methods ◽  
Stiffness Modeling ◽  
Symmetric Configuration ◽  
Parallel Structures ◽  
The Matrix ◽  
Micro Motion ◽  
Good Agreement

Abstract. This paper presents the output decoupling property of planar flexure-based compliant mechanisms with symmetric configuration. Compliance/stiffness modeling methods for flexure serial structures and flexure parallel structures are first derived according to the matrix method. Analytical model of mechanisms with symmetric configuration is then developed to analyze the output decoupling property. The proposed analytical model shows that mechanisms are output decoupled when they are symmetry about two perpendicular axes or when they are composed of either three or an even number of identical fundamental forms distributed evenly around the center. Finally, output compliances of RRR and 4-RRR compliant micro-motion stages are derived from the analytical model and finite element analysis (FEA). The comparisons indicate that the results obtained from the proposed analytical model are in good agreement with those derived from FEA, which validates the proposed analytical model.

On the determination and application of cod to epoxy-bonded aluminium joints

1979 ◽  
Vol 14 (2) ◽  
pp. 37-42 ◽  
Author(s):  
C L Chow ◽  
C W Woo ◽  
J L Sykes
Keyword(s):  
Crack Opening ◽  
Load Control ◽  
Yield Model ◽  
Cohesive Fracture ◽  
Element Analysis ◽  
Testing Conditions ◽  
Strip Yield Model ◽  
Dimensional Finite Element ◽  
Good Agreement

A method of analysis is presented for the determination of crack-opening-displacements (COD) and their application to aluminium—Araldite joint systems. Use is made of a beam-on-elastic-foundation (BEF) model, which is extended to represent the physical system. It is seen that, in conjunction with this, the Dugdale ‘strip-yield’ model solution may be combined to characterize interfacial or cohesive fracture cases. Fracture toughness values, based on both load and displacement control testing conditions, are examined and show that the equation derived for the load-control model yields greater accuracy. Results of the proposed method are compared with those obtained by a two-dimensional, finite-element analysis and are found to be in good agreement. The validity of the proposed analysis is further verified by experimental observations employing conventional compliance methods for both interfacial and cohesive fracture modes.

Estimation of the Crack Behaviour in the Compressive Layer of the Alumina-Zirconia Ceramic Laminate

2014 ◽  
Vol 627 ◽  
pp. 41-44
Author(s):  
Luboš Náhlík ◽  
Bohuslav Máša ◽  
Pavel Hutař
Keyword(s):  
Crack Propagation ◽  
Direct Method ◽  
Zirconia Ceramic ◽  
Finite Element Models ◽  
Linear Elastic ◽  
Dimensional Finite Element ◽  
Density Factor ◽  
Elastic Fracture ◽  
Energy Density Factor ◽  
Good Agreement

This paper deals with a description of the crack behaviour in the layered alumina-zirconia ceramic laminate. The main aim is to investigate the crack behaviour in the compressive layer. The crack propagation was investigated on the basis of linear elastic fracture mechanics. Two dimensional finite element models were developed in order to obtain a stress distribution around the crack tip. The stress intensity factors were computed numerically employing the direct method. The change in the crack propagation direction was estimated using criterion based on the strain energy density factor. Sharp crack deflection in the compressive layer was predicted by mentioned approach. The determined crack behaviour is qualitatively in a good agreement with experimental observations.

Experimental Characterization of Matrix Cracking Behavior in Thermally Cycled CFRP Laminates

2002 ◽  
Vol 11 (3) ◽  
pp. 287-305 ◽  
Author(s):  
Shinji Ogihara ◽  
Akira Kobayashi ◽  
Takamoto Ishiguro ◽  
Nobuo Otani
Keyword(s):  
Thermal Cycling ◽  
Crack Density ◽  
Tensile Loading ◽  
Matrix Crack ◽  
Matrix Cracking ◽  
Thermal Cycles ◽  
Critical Energy Release Rate ◽  
Cracking Behavior ◽  
Cfrp Laminates ◽  
The Matrix

The effect of thermal cycling on the mechanical properties of composite materials is an important issue in engineering, especially in their applications to the space environment. The present study concerned with the experimental study of both the thermal cycling induced matrix cracking and the effect of thermal cycling on the matrix cracking behavior under tensile loading in CFRP laminates. Two kinds of carbon/epoxy systems, T800H/3631 and T300/2500, are used for the laminate configurations of (0/90)s and (90/0)s. The specimens are thermally cycled between −196 and 100°C. Thermal cycling tests are performed up to 1000 cycles. The polished edge surfaces of specimens are examined by the replica technique, and then the matrix crack density is measured as a function of the number of thermal cycles. It is found that the first matrix cracking in (0/90)s and (90/0)s laminates occurs at almost the same numbers of thermal cycles. It is also found that the matrix crack density increases more rapidly in (0/90)s laminates than in (90/0)s laminates in both material systems. To investigate the effect of thermal cycling on matrix cracking behavior under tensile loading, a series of tensile tests on thermally cycled specimens are performed. The effect of thermal cycling on matrix cracking under tension is evaluated in terms of the change in the critical energy release rate and the critical stress for matrix cracking.

Three-Dimensional Finite Element Analysis on Open-Die Block Forging Design

1992 ◽  
Vol 114 (4) ◽  
pp. 459-464 ◽  
Author(s):  
Chinghua Hung ◽  
Shiro Kobayashi
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Rigid Plastic ◽  
Flat Bottom ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
Die Set ◽  
Cylindrical Workpiece ◽  
Three Dimensional Finite Element ◽  
Good Agreement

Three-dimensional rigid-plastic finite element method was used to analyze the practice of open-die block forging, focusing on the effects of die configurations and forging pass designs. Four combinations of die configurations were investigated: conventional flat dies, top flat/bottom V-shaped dies, and double V-shaped dies with 120 and 135 deg included angles. Two different pass designs, 90 and 180 deg rotation angles between succeeding passes, were applied to each die set. The results include the magnitude and distribution of effective strains along the center line of the cylindrical workpiece and the final shape of the workpiece. Good agreement was observed in comparison with experimental data from physical modeling method, and several suggestions were made for choosing suitable dies.

scholarly journals FINITE ELEMENT ANALYSIS OF SHADED POLE MOTOR BASED ON MAXWELL2D

2021 ◽  
Vol 25 (Special) ◽  
pp. 1-115-1-220
Author(s):  
Adnan J. Kazem ◽  
◽  
Amer M. Ali ◽  
Keyword(s):  
Finite Element Method ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Induction Motor ◽  
Single Phase ◽  
Two Dimensional ◽  
Element Analysis ◽  
Analytical Results ◽  
Dimensional Finite Element ◽  
Good Agreement

Shaded pole induction motor is one of the simplest and least expensive types of single-phase motors, but one of the most difficult to analyze. In this paper, we adopted a two-dimensional finite element method 2DFEM, which is one of the most accurate methods to analyze such motors. We used Ansys Maxwell2D software with assist of AutoCAD software in modeling and analyzing a reluctance-augmented shaded pole motor. The 2DFEM results of torques and currents for this motor obtained from Maxwell2D were compared with the analytical results and appeared a good agreement.

Study on Forming Mechanism of Bimetal-Pipe by External Hydraulic Contraction

2018 ◽  
Author(s):  
Quanzhao Sun ◽  
Guolai Yang ◽  
Jianli Ge ◽  
Baochun Lu ◽  
Yanming Song
Keyword(s):  
Finite Element ◽  
Elastic Recovery ◽  
Hydraulic Pressure ◽  
Forming Process ◽  
Element Analysis ◽  
Forming Mechanism ◽  
Upper Limits ◽  
Dimensional Finite Element ◽  
Good Agreement ◽  
Outer Pipe

It is widely known that a bimetal-pipe can be produced by internal hydraulic expansion. An inevitable limitation of which is that the elastic recovery of the outer pipe should be greater than that of the inner pipe when the forming pressure is released. And the existing techniques usually result in plastic deformation of the inner pipe. Considering the circumstance that elastic recovery of the inner pipe is greater than that of the outer pipe, or only elastic deformation in the inner pipe is allowed, an analytical model was developed to investigate the forming process of bimetal-pipes by external hydraulic contraction. The deformation compatibility condition of the bimetal-pipe was obtained according to the deformation rule. The formula relating the applied external hydraulic pressure and the residual contact pressure between the inner and the outer pipes was derived, and the lower and upper limits of the external hydraulic forming pressures were studied. A two-dimensional finite element analysis of the hydraulic contraction forming process of the bimetal-pipe was conducted. The comparison between the theoretical results and the finite element solutions shows that they are in good agreement. The presented methodology can be used in design and manufacturing of bimetal-pipes where the forming pressure should be applied on the outside surface.

Effect of the Carbon Nanotube Distribution on the Thermal Conductivity of Composite Materials

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Iman Eslami Afrooz ◽  
Andreas Öchsner
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Finite Element Analysis ◽  
Composite Materials ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Fiber Volume ◽  
Element Analysis ◽  
The Matrix ◽  
Good Agreement

Finite element analysis has been employed to investigate the effect of carbon nanotubes (CNTs) distribution on the thermal conductivity of composite materials. Several kinds of representative volume elements (RVEs) employed in this study are made by assuming that unidirectional CNTs are randomly distributed in a polymer matrix. It is also assumed that each set of RVEs contains a constant fiber volume fraction and aspect ratio. Results show that randomness—the way in which fibers are distributed inside the matrix—has a significant effect on the thermal conductivity of CNT composites. Results of this study were compared using the analytical Xue and Nan model and good agreement was observed.

scholarly journals Modeling of macro fiber composite actuated laminate plates and aerofoils

2019 ◽  
Vol 31 (4) ◽  
pp. 525-549
Author(s):  
Peter R Thomas ◽  
Ángela Carmen Blázquez Calzada ◽  
Kevin Gilmour
Keyword(s):  
Finite Element ◽  
Composite Laminate ◽  
Numerical Models ◽  
Fiber Composite ◽  
Element Analysis ◽  
Bending Strain ◽  
Glass Fiber Composite ◽  
Macro Fiber Composite ◽  
Distributed Actuator ◽  
Good Agreement

This article investigates the modeling of macro fiber composite-actuated laminate plates with distributed actuator patches. The investigation details an analytical and finite element modeling, with experimental validation of the bending strain and deflection of an epoxy E-glass fiber composite laminate. An analytical approach is also developed to estimate the plate deflection from the experimental strain measurements. The analytical method uses direct integration of single dimensional plate bending moments obtained by strain-induced shear moments from the macro fiber composite actuators. Finite element analysis software was used with the composite laminate modeled in ANSYS ACP. The results from both analytical and numerical models show good agreement with the experimental results, with strain values agreeing within 20 ppm and the maximum difference in deflection not exceeding 0.1 mm between models. Finally, an application of the analytical model for developing morphing aerofoil designs is demonstrated.

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