An investigation of the friction and sliding wear of gray cast iron against chromium plated cast irons was carried out on a newly constructed reciprocating friction and wear tester. The tests were the first to be done on the test rig under dry conditions and at the speed of 170 cm/mm and variable loads of 20-260 N for duration of 15 min to 3 hours. The gray cast iron surfaces worn by a process of plastic deformation at the subsurface, crack nucleation, and crack growth leading to formation of plate like debris and therefore the DELAMINATION theory applies. No evidence of adhesion was observed. This could be due to formation of oxides on the wear surface which prevent adhesion. Channel type chromium plating picked up cast iron from the counter body surfaces by mechanically trapping cast iron debris on and within the cracks. The removal of the plated chromium left a pitted surface on the cast iron.

Composite materials have proven their applicability for various structural components. Excellent properties of glass fiber reinforced plastic (GFRP) composite materials have presented GFRP composites for potential applications in aerospace and automobile-related industries. Drilling is an important operation for composite structures during final assembly. This paper investigates the factors affecting DELAMINATION in GFRP composite during the drilling process. Drill speed and feed rate are selected two parameters affecting DELAMINATION during the drilling process. The response surface methodology approach has been used for experimental design and analysis of variance. DELAMINATION was evaluated at the entry, middle, and exit positions of the hole. An attempt has been made to optimize the speed and feed rate for minimization of DELAMINATION at the three positions using grey relational analysis. The results of this work will help in selecting an optimum level of speed and feed rate to minimize DELAMINATION at the entry, middle, and exit positions of the hole to improve quality of the drilled hole.

In this research work, X-ray diffraction (XRD) tests and petrographic studies are performed to analyze the mineral composition and lamination in the shale rock specimens. Afterward, point load (PL) and uniaxial compressive strength (UCS) tests are carried out on the anisotropic laminated shale rock. Based on the macro-mechanical properties of these tests, the discrete element method implemented in a two-dimensional particle flow code (PFC2D) is adjusted to numerically simulate the shale rock specimens. The aim of this work is to validate the numerical models by failure process, stress-strain curves, and peak failure strengths of the shale samples. Therefore, point load test is used for assessing the pattern failure mechanism, and uniaxial compressive strength test is performed for obtaining the stress-strain curves and peak strength failure points in the laboratory shale rock samples. Validation of peak strengths criteria provides the best results; the determination coefficient values for lab and numerical modeling with (R2 = 0.99). Several numerical models are prepared for estimating the mechanical behavior of shale rocks in PFC2D. The smooth joint model (SJM) is used for preparing the consistent and appropriate constitutive models for simulating the mechanical behavior of laminated shale. It is concluded that SJM provides more reasonable results for laminated shale rock that can be used for several petroleum engineering projects, especially in the central geological zone of Iran.

A finite element model based on the layer wise theory of Reddy is developed for the analysis of DELAMINATION in the [90.0] S cross-ply laminated beams. The Heaviside step function was adopted in the formulation to express the discontinuous interlaminar displacement fields of delaminated layers. Also, to accommodate the moderately large rotations of the beam, the von Karman type nonlinear strain field is used in the formulation. The finite element model is verified by comparing the present solutions with those available in the literature. It is shown that the present finite element model is able to capture accurate local stress fields and the strain energy release rates. Then the model is used to study delaminated cross-ply laminates under bending loads. The influence of boundary conditions and number of layers on the strain energy release rates is studied. Also, the growth of DELAMINATION is investigated for a pure bending case, and the mode of DELAMINATION growth is identified. The influence of geometric nonlinearity on the DELAMINATION growth is also investigated as the DELAMINATION advances. It is found that geometric nonlinearity does not significantly alter the DELAMINATION kinematics and strain energy release rates.