(Manuscript No: I12528-11) April 19, 2012 / Accepted: April 25, 2012 1 Experimental Model of The Semicircular Laminated Composite Curved Bars Serhii Meckaelovech Vereshaka Sumy State University Sumy, Ukraine. Tel: +380 542 334058, Fax: +380 542 334058 (Email: fcerge@yahoo.com) Emad Toma Karash Sumy State University Sumy, Ukraine. Tel: +380 542 334058, Fax: +380 542 334058 (Email: emadbane2007@yahoo.com) Abstract - The classical anisotropic elasticity theory was used to construct multilayer theory for the calculation of the stress and deformation fields induced in the multilayered composite semicircular curved bar subjected to end forces. The radial location and intensity of the open mode radial stresses, tangential stresses were calculated and compared with the results obtained from the experiments results, anisotropic continuum theory and ANSYS method. The multilayer theory gave more accurate prediction of the location and intensity of the open mode radial stresses, tangential stresses and displacements than those calculated from the anisotropic continuum theory. The experimental results were identical to the results of multilayer theory. Keywords: Multilayer theory, Delamination, Anisotropic continuum theory, ANSYS method. Introduction Lightweight structures that meet even exceed the performance and safety requirements in the strictest sense are gaining more importance. Fibres reinforced polymer composites have been shown to perform successfully in many structural applications, and it is expected their use will increase further in the upcoming years. Application of composite materials can be found from aerospace, marine, automotive areas to biomedical implants. Composite materials fall into the general category of anisotropic materials, for which the material properties exhibit directional characteristics. On the other hand the most common engineering materials such as steel etc., are considered isotropic for which there is no dependence of material properties on direction. Isotropic materials can be characterized by two independent material constants only, but for anisotropic materials the number of constants can be as high as 21depending on the number of planes of material symmetry the material possesses [1-6]. In most engineering applications, laminated composite structures have certain curvatures (for example, curved panels and curved beams). If the curved composite structure is .subjected to bending that tends to flatten the composite structure, tensile stresses can be generated in the thickness direction of the com-posites. Also, shear stresses could be induced if the bending is not a "pure" bending. Under normal operations, if the above type of bending occurs cyclically, open-mode delaminations or shear-mode delaminations could nucleate at the sites of peak interlaminar tensile stresses or at the sites of peak interlaminar shear stresses. Continuation of these bending cycling will cause the delamination zones to grow in size and ultimately cause the composite struc¬tures to lose their structural integrity (loss of stiffness and strength) due to excessive delaminations. The type of delamination failure (open mode or shear mode) depends on which type of interlaminar strength (tensile or shear) is reached first [7-10]. The MATH-CAT 14 method were used to perform similar delamination analysis of the multilayered semicircular composite curved bar subjected to end forces and end moments. The resulting predictions of locations and intensities of peak radial stresses are compared with the results of the anisotropic continuum theory presented in reference [9].