An approximate numerical mthod is presented for analysis and determination of modal characteristics in straight, pretwisted non-unifom helicopter blades. The analysis considers the coupled flapwise bending (out of plane), chordwise bending (in plane), and torsion vibration of both rotating and non-rotating blades. The proposed method is based on the integral expansion of Green functions (struct...

A study is presented of the post-buckling behavior and imperfection-sensitivity of complete spherical shells subject to uniform external pressure. The study builds on and extends the major contribution to spherical shell buckling by W.T. Koiter in the 1960’s. Numerical results are presented for the axisymmetric large deflection behavior of perfect spheres followed by an extensive analysis of th...

A low-order mimetic finite difference (MFD) method for Reissner-Mindlin plate problems is considered. Together with the source problem, the free vibration and the buckling problems are investigated. Details about the scheme implementation are provided, and the numerical results on several different types of meshes are reported.

this paper proposed analytical solutions for the buckling analysis of rectangular single-layered graphene sheets under in-plane loading on all edges simply is supported. the characteristic equations of the graphene sheets are derived and the analysis formula is based on the nonlocal mindlin plate. this theory is considering both the small length scale effects and transverse shear deformation ef...

the subjective of this study was to explore and compare the effects of whole body vibration (wbv) and conventional spinal stabilization exercises on persons with non-specific chronic low back pain (clbp). thirty patients with non-specific chronic low back pain randomly received 6 sessions of spinal stabilization therapy with and without whole body vibration over 2 weeks. the severity of pain, f...

background: deficiency of attention and concentration is one of great reasons of traffic incidents and it covers between 20 to 50 percent of events due to careless and mindedness. studies show that attention and concentration are considered as one of important cognitive components in safe driving. vibration is an important physical effect in all vehicles. till now has not been any organized stu...

The presence of the delamination causes reductions in the bending stiffness which in turn leads to the undesirable loss in the compressive buckling and post-buckling strength. Thus, it is of chief importance to investigate the compressive behavior of composites with delaminations. Anastasiadis et al. analyzed the buckling and postbuckling behavior of delaminated composite laminates with a throu...