Applied Mechanics and Materials Vols. 752-753

Abstract: The relationships between drill speed, whirl, squeeze effect and fluid force drill suffered is got by using cutting fluid Reynolds equation. Principle of deep-hole drilling drill whirl is studied, pointing out the promotion of positive precession cutting fluid component is drill whirl’s reason. Simulated and studied of drill whirl round shape at different times, suggesting that only when BTA drill suffered by the fluid force, stable motion can be obtained. Analysis of the anti-precession of drill, and the squeeze film damper work principle is revealed. Comparative studied the movement of the drill by using MATLAB software simulation before and after adding squeeze film damper.

Abstract: In this study, an investigation on mechanical properties of flax/vinyl ester natural fiber composite was performed. Vacuum Assisted Resin Transfer Molding (VARTM) manufacturing method was adopted for manufacturing the flax fiber composite specimen. The mechanical properties of the manufactured flax composites were compared with flax composite data cited from some references. Based on this, the experimental data showed that the flax/vinyl ester composite has some advantages when it is applied to environment-friendly structure.

Abstract: When the cross-sectional area of the specimen for the Kosky bar experiment (Split Hopkinson bar) is very small compared to the area of the input bar, most stress wave will be reflected and the signal detected by the strain gage attached on the output bar is very weak. The signal to noise ratio is very significant so that smoothing process is necessary to obtain meaningful results. To improve the design of the experiment, 2-dimensional finite element calculations are carried out for various specimen thickness and length and elastic stiffness of the bar. It is found that short specimen with large contact area and bar material with low stiffness give better results.

Abstract: Technological features of pulsed laser machining of yttriastabilized tetragonal zirconia polycrystal (Y-TZP) were studied. The connection between the laser power, scanning speed, laser beam steps and surface state of zirconia ceramic was established. The results of the research showed that pulsed laser machining of this material is an effective tool to control surface modification process and presents an attractive alternative to conventional techniques.

Abstract: Selective laser melting (SLM) has been recognized as a pertinent process for manufacturing of complex geometries. Al 4047 has been manufactured in this study with different processing parameters of the SLM process to obtain the optimal parameters suitable for required applications, as well as to determine the effect of these parameters and post-processing heat treatment on mechanical properties. A unique Al-Si eutectic microstructure is obtained with Al dendrites growing in the scanning direction. Mechanical properties of the SLM manufactured Al 4047 are at par with those of conventionally manufactured alloy. These properties can be varied by changing the SLM process parameters which can help controlling the process cost depending upon required mechanical properties.

Abstract: A dedicated or specialized friction stir welding (FSW) machine is quite costly especially for pipe joining. Therefore, not many institutions manage to conduct their research on FSW at their facilities. Besides that, the difficulty to design a jig that can hold the complex shape such as pipe section tightly and easily to be removed during and after the FSW process respectively will nullify the intentions. In many institutions, there was either conventional or CNC milling machine available in their workshops. Thus, a jig called orbital clamping unit (OCU) was designed to suit this milling machine. It acts as an additional device to enable this milling machine to run as FSW machine at a lower cost, hence fully utilized the available facility in the workshop. Several good samples were successfully produced by using this jig and milling machine

Abstract: The material defects in automobile industry caused by correction can be found in different components, such as welded and fastened areas in cars and vehicles. The corrosion appears when components with different conducting properties assembled together in electrolyte substances. Different conducted materials show different potentials which will lead corrosion. The corrosion in components can cause many product problems, such as bad quality, less safety, lower energy efficiency, and higher cost. This paper analyzes the rusty mechanism and anti-corrode in regular coating and nanocoating materials via computer-aided simulation and prototype testing. Both computational simulation and sample testing displayed almost equal results that validate the credibility of analytic method proposed in this paper. Keywords: Nanocoating technology, computational simulation, corrosion control, anti-corrosion, computer-aided modeling

Abstract: Tungsten Inert Gas (TIG) welding process requires high heat input during the process, when the material is cooled down non-uniform distribution of thermal strain causes residual stress which can weaken the material and fatigue life of the material. The residual stress can be measured from method such as x-ray diffraction (XRD), using strain gage of drilled hole and so on. A numerical method of constructing a finite element analysis (FEA) model can be used for predicting the residual stress level of the welding process. This paper uses the TIG welding condition for stainless steel grade 304 that the material provided the highest level of tensile strength, obtained from previous study, as a condition for the FEA model. The residual stress results from the FEA predictive model and the results from XRD were compared. In the FEA model, the workpiece, heat affected zone (HAZ), and filler metal assumed to be the same. The results showed consistent residual profile between the model and the actual measurement from XRD, but there was some discrepancy of the magnitude of residual stress which can due to the type of filler material that was used.

Abstract: The present study investigates the behavior of axial loaded circular concrete filled hollow steel section (CFHSS) columns. A nonlinear finite element model using ABAQUS program was developed to investigate the fire behavior of the inspected columns from previous fire tests. The study variables include column dimensions, steel section wall thickness, concrete strength, concrete types (plain or reinforced), and fire protection thickness. The comparison indicated that the results obtained from the model were within acceptable limit of accuracy of 15%. A sensitivity study was carried out to investigate the influence of the output of the numerical model including the Poisson’s ratio of concrete, thermal conductance at the steel-concrete interface, frictional contact at steel-concrete interface, and imperfection buckling of columns. Based on the sensitivity analysis, several modelling suggestions were given in this paper which will be beneficial for further study.

Abstract: Rubbercrete is a concrete containing crumb rubber as partial replacement to fine aggregate. Advantages of rubbercrete have been reported by many researchers. In contrast to normal concrete, rubbercrete is a more ductile which can be used in areas prone to earthquake. In this paper seven reinforced rubbercrete beams without shear reinforcement are fabricated and tested up to failure. Three parameters are considered: beam width, effective depth and a/d. The experimental results are then compared with available shear quations. Available shear quations have produced conservative shear stress prediction for the reinforced rubbercrete beams.