Zakri Ghazalli

Design of electrostatic comb actuators based on finite element method

Electrostatic comb actuators are commonly used to provide displacement-invariant force in micro electro-mechanical system (MEMS). Major application can be found in resonator, inertial sensor, accelerometer, and gyroscope. The size of the comb may be a few microns to millimeters. Principally, the electrostatic force is produced in the comb structure due to potential difference between the electrodes, which is used to actuate the system attached to it [1]. The higher forces are very often desirable for high sensitivity and performance. However to meet this demand, micro-scaled structures are very often fabricated on trial-error basis because of lack of well-established fabrication method. In this situation, designing on a computer prior to the actual fabrication would be very helpful. Moreover, in a virtual device, parameters can be changed much more quickly than trial-and-error fabrication reducing the time to market and also the cost to develop a commercial device considerably [2].

Investigation on musculoskeletal discomfort and ergonomics risk factors among production team members at an automotive component assembly plant

Musculoskeletal discomfort (MSD) is very common condition in automotive industry. MSD is affecting the workers health, well-being and lower down the productivity. Therefore, the main objective of this study was to identify the prevalence of MSD and ergonomics risk factors among the production team members at a selected automotive component manufacturer in Malaysia. MSD data were collected by conducting structure interview with all participants by referring to the Cornell Musculoskeletal Disorder Questionnaire (CMDQ). Those production team members who achieved a total discomfort score for all body regions more than 100 was selected for job task assessment. The physical exposure risk factors of work related musculoskeletal disorders (WMSD) has evaluated by using Quick Exposure Check (QEC) techniques. The results of the study identified the severe MSD associated with production assembly team members. It is expected that the prevalence of MSD for those production assembly team members was lower back (75.4%), upper back (63.2%), right shoulder (61.4%), and right wrist (60%). The QEC analysis discovered that about 70% of job tasks had very high risks for neck posture and 60% had high risks for the back (in moving condition) and shoulder/arm postures. There were 80% of respondents have produced a high score for exposure risk to vibration. As a conclusion, the main implication of the current study is that special attention should be paid to the physical and psychosocial aspects in production team members with musculoskeletal discomfort to improve their safety, health, and well-being, maintain work ability and productivity.

Design of an Electrostatic Comb Actuator Based on Finite Element Method

Electrostatic comb actuators were designed using finite element modeling and analysis, so‐called finite element method (FEM). Design objective was to generate maximum actuating force within the constraints. 2D and 3D FE models of the comb structures were developed in general‐purpose FE code. The element geometries were 4‐node plate element for 2D model and 8‐node brick element for 3D models. Electrostatic field strength and voltage analysis of the FE models were performed to compute generated voltage and electrostatic force in the structure. Subsequently done was the structural analysis to examine structural response to the electrostatic force. The initial finite element model was verified with the published experimental result. Based on the amount of force generated and lateral deflection of the comb fingers, the best possible design of choice was determined. The finite element computations show that the comb structure having high aspect ratio with smaller gaps can provide higher actuation force.

A Knowledge-Based Ergonomics Assessment System for WMSD Prevention Using AHP Methodology

This research develops a knowledge-based ergonomics assessment system (KBEAS) that measure and predicts the degree of criticality of risk factors related to work-related musculoskeletal disorders (WMSD). Predicting WMSD individual risk level provides critical decision support information to occupational safety and health (OSH) practitioners in the ergonomic analysis. The KBEAS is based on the analytic hierarchy process (AHP) methodology. The current study integrates AHP method with real workplace ergonomics risk data and design web-based system assisting a sensible multi-criteria WMSD related risk factors. The objectives involve knowledge acquisition performed through preliminary study, MSD symptom study, literature analysis, and tacit knowledge analysis and practitioner survey to identify the ergonomics risk factors that include individual, organizational, physical and psychosocial. The application of this system shows that the design of the proposed KBEAS for WMSD risk factors has been validated and gets each risk factors weight easily by using AHP. The study findings showed that ‘organizational ergonomics risk factors’ is more critical than other factors. The overall prioritization revealed that ‘exposure to physical demands’ had a priority vector of 26.33%, and it was perceived as the item with the most critical factor. The KBEAS could help the user to make an objective judgement on the subjective description and get the correct result of the ergonomics risk factors.

A Future Framework of Knowledge-Based Ergonomics Assessment System at Workplace in Automotive Assembly Plant

There are several parameters must be correctly evaluated to guarantee a good level of interaction between worker and working system, in order to avoid safety and health problems. The lack of attention to occupational ergonomics issues may to potential ergonomics risk for which decision makers are ignore when develop new product and process. This paper proposed a novel framework to facilitate the ergonomics knowledge management for occupational risk assessment. It serves two objectives, the first objective is to aid the decision makers predicting ergonomics risk element at early stage of development product and process. The second objective is to develop knowledge-based ergonomics assessment system (KBEAS) in automotive assembly plant. The respondents of the study are about 250 and consist of assembly workers ranging from operator to executive level in automotive component assembly plant. The activities of direct observation, activity analysis, photography, video, survey questionnaire and interviews, are employed to measure the occupational ergonomics risk factors. The outcome of these activities will be used as an input for analytical hierarchy process (AHP) technique to prioritize the occupational ergonomics risk ate workplace. The outcome of this framework could ease decision makers in assessing and prioritizing the ergonomics risk at the early stage of product and process in automotive component manufacturer.

Analysis of an Olympic Scale of a Recurve Bow Riser on the Basis of Malaysian Under 15 and Under 17 Archers

Recurve bow is the only type of bow that used in Olympic Games. To date, none of this bow that suits to Malaysian junior archers. This paper aims to analyze a recurve bow riser on the basis of Malaysian anthropometry. Anthropometric data of Malaysian population was gathered to analyze the loads during drawn bow. A static structural analysis of the Matrix riser was executed on a final design of recurve bow riser. The finding from this study shows that the maximum displacement of recurve riser is correspondence to the established previous study. It can be concluded that the design of recurve bow riser can sustain the force applied by Malaysian junior athletes when they aim the target board at a full drawn bow position. The developed bow riser can be very beneficial for both athletes and coaches during training.

A Comparison of Muscular Activity among European, Korea and Malaysian During Seating Using Musculoskeletal Computational Analysis Method

Sitting is the most common posture in any industry field either in office work, manufacturing or even automotive. Sit for a long time lead to musculoskeletal disorder which causes muscle fatigue. However, different size of people will have a different level of muscle activation. The objective of this paper is to analyse and compare the muscle activation during sitting among European, Korean, and Malaysian. The human size employed for this study is by 95th percentile male. The AnyBody Modelling Software is used to simulate and analyse the human muscle activity of the seating posture of these respective countries. Our finding showed that the trunk of the human body has the highest muscle activity. The Malaysian anthropometry showed the highest muscle activity in sitting posture; followed by Korean and European.