Applied Mechanics and Materials Vol. 902

Abstract: Newly developed lead-free solder alloys, which contain doping some elements such as Ni, Bi, Sb, Al,..., have improved properties with respect to the conventional solder alloys, particularly in terms of resistance to creep. Their high performances are specifically desired in applications of power electronics where they are used for the electrical interconnections between the components. Studies on their resistance to rupture remain relatively limited. Yet the comprehension of fracture behavior is essential for the correct design of the electronic packages which must be robust against fatigue and vibrations loads. In this study, rupture of notched specimens fabricated from the InnoLot lead-free solder alloy is investigated. The tests are performed with the help of a micro-tensile testing machine equipped with an optical system for full-field measurements with Digital Image Correlation. The images are taken at successive steps of deformation and the displacement field is measured in a region of interest which is the singularity dominated zone surrounding the plastic zone at the crack tip. The procedure consists then in comparing the measured field with the theoretical field given by the Williams’ solution. The stress intensity factor is calculated by fitting the analytical fields to the experimental data. The effects of the size and shape of the zone of data collection, as well as that of the number of terms considered in the Williams’s expansion series, are examined in the study. A method is also proposed for the automatic crack tip detection.

Abstract: This paper presents a complete case study for designing and manufacturing chain parts for chain conveyor use for a harvest shallot for a real. The process of harvesting shallot in Vietnam is being done manually. Mechanization, automation of the harvest process has been demanded by farmers. In the harvest shallot equipment, the chain conveyor system is used to handling the desired orbit to the packing position. Shallots are uneven in size, distributed in a certain size range. Chain conveyor systems with the chain was non-standardized were choiced. Therefore, a complete design is required to meet requirement. The design procedures are: (1) calculation of the expected loads that exert on the chain during operation, (2) selection of materials, (3) designing the different parts of the chain taking into account safety, assembly process and economic considerations. The final design was justified and validated. The chain of chain conveyor system is working properly and safety under real conditions.

Abstract: This paper presents a prediction of cutting temperature in turning process, using a continuous cutting model of Johnson-Cook (J-C). An method to predict the temperature distribution in orthogonal cutting is based on the constituent model of various material and the mechanics of their cutting process. In this method, the average temperature at the primary shear zone (PSZ) and the secondary shear zone (SSZ) were determined for various materials, based on a constitutive model and a chip-formation model using measurements of cutting force and chip thicknes. The J-C model constants were taken from Hopkinson pressure bar tests. Cutting conditions, cutting forces and chip thickness were used to predict shear stress. Experimental cutting heat results with the same cutting parameters using the minimum lubrication method (MQL) were recorded through the Testo-871 thermal camera. The thermal distribution results between the two methods has a difference in value, as well as distribution. From the difference, we have analyzed some of the causes, finding the effect of the minimum quantity lubrication parameters on the difference.

Abstract: System engineering methods are often used to design complex systems like airplanes. However, this method is also useful to propose solutions to redesign logistics systems such as warehouses and transport systems. This paper will apply system engineering in analyzing the late order problem at a pesticide company, thereby surveying stakeholders needs for warehouse re-designing. The functional analysis in the warehouse will be carried out in the concept analysis section to propose warehouse’s layout redesign alternatives that based on the demand of storage capacity and throughput. The authors also used the AHP method to select the final design layout. The detailed design section builds the operation process for the warehouse as well as the codification for commodity storage slots along with these tables forms that support for warehouse management. These solutions increase warehouse performance as well as the utilization in warehouses when applied in practice. Therefore, the system engineering method should be used in warehouse’s redesign

Abstract: Cam mechanisms are used as the control system in several industrial fields such as filling and canning, textiles, automotive. This paper introduces the development of a software for designing planar cam mechanism adapting the dynamic and kinematic requirements. The designed cam profile is then changed into numerical data used to generate the machine codes served for CNC-based fabrication. Traditional cam design is very complicated and has accumulated errors. The envelope theory and inverse method are utilized to perform constraint in pressure angle and motion. The smallest cam radius is then determined in a non-linear optimization adapting the constraints. The paper also presents the design of a CNC machine for cam profile fabrication. The design includes the control system and the circuit board. The CNC control program is built to receive numerical data from cam design section, to simulate the cam profile fabrication and then to fabricate. The optimal design and fabrication are applied to the cam mechanisms with knife-edge/roller reciprocating/oscilating followers. The verification shows that the designed and fabricated cam adapts the requirement of accuracy.

Abstract: The dynamic process of an underwater explosion (UNDEX) is a complex phenomenon that involves several facets. After detonation, the shockwave radially propagates at a high speed and strikes nearby structures. Subsequently, bubble oscillation may substantially damage the structures because of the whipping effect, water jet impact, and bubble pulse. This paper presents an application of explicit finite element analyses to simulate the process of an UNDEX bubble in the vicinity of rigid wall, in which the coupled Eulerian-Lagrangian (CEL) approach was developed to overcome the difficulties regarding the classical finite element method (FEM), large deformations, and flow simulation of fluid and gas. The results demonstrate that the method is well suited to manage the UNDEX bubble problem and can be used to model the major features of the bubble dynamics. Furthermore, the behavior of an UNDEX bubble near a rigid wall was also examined in the present study, which showed that the migration of the bubble and the development of the water jet are influenced strongly by the standoff distance between the initial bubble position and the wall. This method can be used in future studies to examine UNDEX bubbles in the vicinity of deformable and complex structures.