Finite Element Analysis of Plate Structure Excited by Patches of Piezoelectric Actuators

Active damping using piezoelectric element is one of the effective technique to counter vibration problems. A 3D finite element model is developed as part of investigation for active damping control. The piezoelectric are surface bonded with quadrilateral thin plate and supported with spring damper elements. This simulation project focuses on analysis of the piezoelectric actuators to achieve active damping on plate structure at low frequency spectrum. By numerical simulation the effect of the system in actuator mode at appropriate electric excitation from piezoelectric actuator are investigated. The force induced by piezoelectric actuator under certain applied voltage fields is used as load. Natural frequency of the system and corresponding mode shape are presented and the double symmetric mode shapes are examined. The result can be used as reference or validation of optimal locations and configuration of the piezoelectric patches for active damping control system

Analysis of unimorph piezoceramic patches on damped square shaped plate

Active damping using piezoelectric element is one of the effective techniques to counter vibration problems. A 3D finite-element model is developed as part of investigation for damping control. The piezoelectric patches are surface bonded on quadrilateral thin plate and supported with spring damper elements. The main goal of this paper is to investigate mechanical characteristics of piezoceramic array on membrane and the effect of force excitation using small motor and electric excitation on the system. The system setup produced small vibration displacement and does not displace the plate beyond elastic strain region. The results show the linear behavior of piezoceramic and the correlation between electric excitation, motor vibration and displacement at the centre of the plate at different frequency range. The mode shapes and natural frequencies at low frequency spectrum are also presented. Therefore, the results can be used as reference to develop damping system with aid of piezoelectric patches

On Lower-back Pain and Its Consequence to Productivity

Manual handling is the primary cause of musculoskeletal disorders, such as sprains and strains and joint disorders, which account for more than half of all injury claims. If motions are repeated frequently, such as in every few seconds, and for prolonged periods such as an eight-hour shift, fatigue and muscle strain can acquire. Working hours is lost every year by means of injury, and personal injury situations and compensation packets are costly. Employers could boost productivity by training their workers to handle loads the right way, or by providing materials-handling equipment to aid them with the job

Changes in physicochemical and microbial community during co-composting of oil palm frond with palm oil mill effluent anaerobic sludge

The aims of this study were to investigate the physicochemical changes and microbial population during co-composting of 1 ton oil palm frond (OPF) with 1,000 L palm oil mill effluent (POME) anaerobic sludge. In the first 30 days of composting, the temperature of the composting piles was observed in the thermophilic phase, within a range of 50 - 56 °C. Meanwhile, the oxygen level, moisture content, and pH profiles of the compost were maintained at 2.0 to 12%, 60 to 70%, and 7.9 to 8.5, respectively, throughout the composting process. The total bacteria count was estimated to be about 55 x 1010 CFU/mL in the mesophilic phase, and then it increased up to 66 x 1010 CFU/mL in the thermophilic phase, and finally decreased to 9.0x1010 CFU/mL in the curing phase. The initial C/N ratio, 64, decreased to 18 after 60 days of composting process, indicating the maturity of compost product from OPF-POME anaerobic sludge. The diversity of the bacterial community was investigated using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis. The results suggested that the co-composting process of OPF with POME anaerobic sludge was dominated by Pseudomonas sp

Reliability Assessment Of Self-Alignment Assemblies Of Chip Component After Reflow Soldering Process

Reliability of surface mount components and interconnect are significant issues in electronic manufacturing. Although the reliability of devices has been broadly studied,here we are focusing on the reliability of the solder joint after the self-alignment phenomena during reflow soldering.In this study,the quality of the self-alignment assemblies was analyzed relate to the joint shear strength according to the JIS Z3 198-7 standard and the inspection according to IPC-A-610E standard.The results from reliability study indicate that the shear strength of the misalignment component of solder joints indeed depends on the degree of chip component misalignment.For shift mode configuration in the range of 0-300µm,the resulted chip assembly inspection after the reflow process was in line with the IPC-A-610E standard

Soldering Characteristics And Thermomechanical Properties Of Pb-Free Solder Paste For Reflow Soldering

A deep understanding in thermal characteristics of lead-free solder paste grades is one of the most crucial factors when dealing with reflow soldering process. These temperatures are critical parameters for proper settings of the real reflow process. This report is devoted to discussing the findings obtained during utilization of differential scanning calorimetry (DSC) and calculation using MATLAB to identify the latent heat, solidus and liquidus temperature, and surface tension applicable to numerically simulate the real process of reflow soldering. It can be stated that the equilibrium solidus and liquidus temperatures during solidification process are not a reversal of the melting process, with the solid phase equilibrium occurred at a lower temperature due to the difficulty of ß-Sn nucleation. Amount of heat energy released during solidification differs less than 10% for SAC405 and less than 1% for SAC105 with the latent heat of fusion during the melting process

Motion Synthesis Of Planar Four Linkage Movement For Part Flipping Application

Designs methods for four linkages encompass mathematical approach, trial and error method, function generation, motion synthesis and path synthesis. Various literatures found used mathematical approach to find specific solution. This main goal of this paper is to provide study of motion synthesis of four bar mechanism to find solution for mobile parts flipping application. Systematic procedures for motion synthesis to determine the length and position of the links in case of desired positions of a coupler are presented. The graphical method provides quick solution for designer regarding kinematic problem without involvement of complicated mathematical equation. Part of the solution is compared with mathematical approach and simulation approach. As a conclusion, the graphicaI approach result match with other method and helpful to provide better insight of the system during designing the solution

Gnielinski method in calculating the heat transfer coefficient for metallic solar tower absorber

This work is done to calculate the heat transfer coefficient of metallic wire mesh to air in an open volumetric thermal absorber. It is aimed to replace the actual ceramic with metallic which latter has better thermal properties in order to increase the efficiency of the concentrating solar power plant. The calculation of the heat transfer coefficient from porous wire structure to the air has been conducted to pursue the purpose. The structure that has been chosen is a set of metallic wires with aligned and shifted configurations. The variations of wire diameter together with various porosities from 0.10 to 0.50 have been calculated to obtain the best configuration for the absorber. The flow characteristic within the mesh structure in terms of Reynolds number and its relationship with the heat transfer coefficient has been obtained. The condition on mass flow rate of heat transfer medium and other aspects which influence the heat transfer are also discussed

Consanguinity and reproductive health among Arabs

Consanguineous marriages have been practiced since the early existence of modern humans. Until now consanguinity is widely practiced in several global communities with variable rates depending on religion, culture, and geography. Arab populations have a long tradition of consanguinity due to socio-cultural factors. Many Arab countries display some of the highest rates of consanguineous marriages in the world, and specifically first cousin marriages which may reach 25-30% of all marriages. In some countries like Qatar, Yemen, and UAE, consanguinity rates are increasing in the current generation. Research among Arabs and worldwide has indicated that consanguinity could have an effect on some reproductive health parameters such as postnatal mortality and rates of congenital malformations. The association of consanguinity with other reproductive health parameters, such as fertility and fetal wastage, is controversial. The main impact of consanguinity, however, is an increase in the rate of homozygotes for autosomal recessive genetic disorders. Worldwide, known dominant disorders are more numerous than known recessive disorders. However, data on genetic disorders in Arab populations as extracted from the Catalogue of Transmission Genetics in Arabs (CTGA) database indicate a relative abundance of recessive disorders in the region that is clearly associated with the practice of consanguinity