Iraqi journal of mechanical and material engineering

The aim of this papers is studied effect of tool pin geometry and welding parameters (rotation speed and welding speed) on the mechanical properties and microstructure of 2024-T3 welded by FSW. Three different tool pin geometry (tapered cylindrical threaded pin TCT, straight cylindrical threaded pin SCT and triangular threaded pin TT) with variable rotation speed (710, 900 and 1120) RPM and constant welding speed (26) mm/min. results showed quality of the weld and the mechanical properties (ultimate tensile strength, yield strength and elongation) effect with different pin geometry and welding parameters. TCT tools gives maximum tensile strength as compared with SCT and TT equals to (410MPa) and joint
efficiency (85.25%) of base metals at rotation speed (900RPM) and welding speed
(26mm/min). The microstructure of the weld nugget is fine and equaixed in all the tools
compared with base metal and grain size increased with increased rotation speed because
increase heat input.

An experimental investigation had been done to demonstrate the dynamic behavior of laminate composite plate. Four types of composite plates were produced that (E-glass woven roving + unidirectional carbon / unsaturated polyester, E-glass woven roving + unidirectional carbon/ epoxy, unidirectional carbon / unsaturated polyester and unidirectional carbon/epoxy) with 6 layers at (30%) fiber volume fraction. Mechanical properties were evaluated in terms of tensile and impact strengths. In fatigue tests, the specimens were investigated to estimate the basic S-N curve and deduce their relations. Plate fixed from all sides and a steel ball of 23g was freely dropped from height of 1m. Dynamic response of plate was investigated by measuring strain using vibration data collector (TVC200). The mechanical properties and the dynamic response tests done at 30ºC, 0ºC and (-30) ºC temperature which is realistic and exist within everyday life in winter. A special refrigerator for this purpose was manufactured to get the temperature required. The results showed that the Carbon/Epoxy composite plate has higher mechanical properties and fatigue limits, with lower deflection as compared with other plates. The mechanical properties were found to be increased and the deflection decreased with the temperature decreased.

A study of dynamic buckling behavior (experimentally and numerically) under increasing load had been conducted on medium carbon steel (CK35) specimen. 24 specimens were tested under compression loading, 12 specimens are long and others are intermediate. All these specimens were tested under four shot peening times (SPT) (0, 15, 25, 30) minutes. It was concluded that, the best buckling strength was appeared at (25 min) shot peening time. Also, the comparison between the experimental and numerical results showed good agreement between these results with maximum difference was about (12%).

This paper presents the design of a cognitive dynamic neural controller (CDNC) for the trajectory tracking of non-holonomic wheeled mobile robot based on the dynamic model with self-tuning on-line optimization algorithm. The aim of the proposed controller is to solve the trajectory tracking problem of the mobile robot by finding the optimal torque control action for the two wheels of mobile robot to follow a pre-defined continuous path precisely and quickly. Particle swarm optimization (PSO) used as a fast and stable self-tuning on-line algorithm to compute the optimal parameters for the proposed controller .The robustness and effectiveness of the proposed tuning algorithm are validated by Matlab simulation results in terms of the capability of overcoming the non-representative dynamic disturbances, minimizing tracking error and obtaining the smooth and optimal torque control signals with minimum number of fitness evaluation.

Spinning sheet metal forming (SSMF) has demonstrated a great potential to form a wide range of industrial products which have an axially symmetric shape. This process produces a part with a good surface finish and high mechanical properties by using simple tools. In this study, the deformation mechanics were investigated by using two approaches, theoretical and experimental. The theoretical part included finite element models of cylindrical cups of Aluminum1435 using single roller passes and Finite Element code (ANSYS 15) were used to simulate the forming process and analysis the results theoretically. The effect sheet thickness on the final product quality, stress distribution were studied. The experimental study focused on the analysis of the shape accuracy produced by single pass metal spinning. The numerical results were obtained in this study revealing that, failure by fracture is a predominant when a sheet with 1mm thickness is used, while failure by wrinkling was observed when a sheet with 2 mm thickness was used, the product with 3mm thickness showed no defects. The experimental work included design and manufacturing of the forming tools can be fitted on the tool post of lathe after some modifications. The results of the thickness variation along the cup wall was measured and compared with that obtained numerically. The compared results showed a good agreement between them and the error percentage did not exceed 5.95%.

In this research an algorithm to generate NC tool path had been developed for machining sculptured surfaces depending on the preparation functions (G02, G03) which are special type of circular interpolation and compare it with the other paths of the linear interpolation that generated using (G01) function from package program. In the design stage Bezier technique had been used to represent the proposed surface. Mathematical equations to estimate (radius of curvature, normal vector of the curve, cutter contact & cutter location points) had been driven to generate a tool path and get the (G-code).The MATLAB program had been utilized so as to facilitate the process of calculation. In addition, four types of tool path strategies had been selected based on linear interpolation using (UGS) program which are {Zig, Zig-Zag, Zig in (w) and Zig- Zag in (w) direction}. A comparison between G-code type of circular interpolation and G-code type of linear interpolation had been done for each type of selected tool path strategies with the original data of the proposed design form. A practical aspect side had been implemented using 3-axis vertical CNC milling machine for eight specimens which are divided into two groups: four specimens for the G-code that generated using the proposed method and the others for the G-code generated using the (UGS) program. The proposed algorithm had been implemented and the results showed that the specimen of the type Zig in (w) direction that generated depended on circular interpolation gave closer to the original surface results, compared it to linear interpolation of the path type Zig-Zag in (w) that generated using UGS program.

Computers have been used for numerous applications involving the automatic or semiautomatic recognition of patterns in image. Advanced manufacturing system requires automated inspection and test method to increase production and yield best quality of product. Methods are available today is machine vision. Machine vision systems are widely used today in the manufacturing industry for inspection and sorting application. The objective of this paper is to apply machine vision technology for measuring geometric dimension of an automotive part. Vision system usually requires reprogramming or parameterization of software when it has to be configured for a part or product. A web camera used to capture an image of an automotive part that has been chosen. In the machine vision, Matlab software is used to develop an algorithm to measure a geometric dimension of the part. The measurement system has been calibrated using gauge block. This work considers the factor influencing parameters on accuracy and precision of calibration as the pixels were used to perform the unit of measurement. This measurement has been performed by the conversion through the equation of the image processing. Formulation of the calibration is important from unit in pixel to mm taking into account the perfective effect of the camera view. Finally the measurement system has been tested for accuracy and precision.

In this study, porous copper was produced using powder metallurgical techniques. Zinc element (21%wt) was used as a transitional element to be pulled during sintering process under vacuum environment. A set of samples was produced with different sintering’s conditions to investigate the optimal parameters for production of porous copper. SEM test was used to measure the resulted porosity for the prepared samples. It was found that 3 hours is a sufficient duration for the first stage of sintering at (350oC) and for the second stages at (850oC) to pull all of the zinc vapors and thus get the highest percentage of porosity for the remaining copper which was found to be (19%).

The static pressure of two phase ( liquid - Solid ) fluidized bed was investigated experimentally in this work for different values of the ratio static bed height over the diameter of the bed column (H/D) (0.59, 0.98, 1.38) and liquid phase velocity (0.16, 0.49, 0.82 m/s). As well as the expansion of the bed visualized experimentally has compared with the solid volume fraction found numerically. The fluidized system consists of glass test pipe of 1m height and 0.0254 m diameter inserted with stainless steel particles of 1.5 mm diameter fluidized by water. Pressure was measured by pressure sensor located at four tapes on the side of the fluidized bed pipe. High speed camera was used to photograph the flow in the test pipe. The experimental results compared with computational fluid dynamics model simulated by ANSYS FLUENT version 15.0. The results were in a good agreement with the experimental data.