Nor Azali Azmir

Hand-arm vibration disorder among grass-cutter workers in Malaysia.

Introduction. Prolonged exposure to hand-transmitted vibration from grass-cutting machines has been associated with increasing occurrences of symptoms and signs of occupational diseases related to hand–arm vibration syndrome (HAVS). Methods. A cross-sectional study was carried out using an adopted HAVS questionnaire on hand–arm vibration exposure and symptoms distributed to 168 male workers from the grass and turf maintenance industry who use hand-held grass-cutting machines as part of their work. The prevalence ratio and symptom correlation to HAVS between high and low–moderate exposure risk groups were evaluated. Results. There were positive HAVS symptoms relationships between the low–moderate exposure group and the high exposure group among hand-held grass-cutting workers. The prevalence ratio was considered high because there were indicators that fingers turned white and felt numb, 3.63, 95% CI [1.41, 9.39] and 4.24, 95% CI [2.18, 8.27], respectively. Less than 14.3% of workers stated that they were aware of the occupational hand–arm vibration, and it seemed to be related to the finger blanching and numbness. Conclusion. The results suggest that HAVS is under-diagnosed in Malaysia, especially in the agricultural sectors. More information related to safety and health awareness programmes for HAVS exposure is required among hand-held grass-cutting workers.

Optimization of Sound Absorbers Number and Placement in an Enclosed Room by Finite Element Simulation

Giving a room proper acoustic treatment is both art and science. Acoustic design brings comfort in the built environment and reduces noise level by using sound absorbers. There is a need to give a room acoustic treatment by installing absorbers in order to decrease the reverberant sound. However, they are usually high in price which cost much for installation and there is no system to locate the optimum number and placement of sound absorbers. It would be a waste if the room is overly treated with absorbers or cause improper treatment if the room is treated with insufficient absorbers. This study aims to determine the amount of sound absorbers needed and optimum location of sound absorbers placement in order to reduce the overall sound pressure level in specified room by using ANSYS APDL software. The size of sound absorbers needed is found to be 11

Modelling of Rigid Walled Enclosure Couple to a Flexible Wall using Matlab and Ansys APDL

Generally, solutions to improve the noise problems in enclosure are to redesign or modifying the system such as increasing the thickness of the wall panels, enhancing the elasticity of the structure, and increase the damping mechanism of the wall structure. In this paper, the application of vibroacoustic modelling of enclosure coupled to a flexible wall was presented. The sound pressure characteristics of rigid walled enclosure, such as natural frequency and mode shape were determined using two approaches which are finite element simulation of Ansys® and mathematical model. The mathematical equations derived in Matlab® such as rigid walled enclosure and rigid walled enclosure coupled to flexible wall were used to validate finite element analysis (FEA). The result indicates that the theory and FEA display in a good agreement. Thus, proved that the FE model was accurate and can be applied in further research such as sound pressure and noise attenuation in enclosure.

Predicting hand numerical scoring of vibration exposure using an artificial neural network

Ergonomic researchers are investigating the cause and effect relationship due to hand transmitted vibration exposure. These relationships make occupational safety and health practitioners determine the possible root or intermittent cause which can be harmful to workers using an artificial intelligence system. In maintenance of the agriculture sector, there is a need to study hand–arm vibration exposure due to significant vascular and sensori-neural disorder. This paper presents the development of a hand numerical scoring prediction model among grass cutter workers in Malaysia using an artificial neural network. In this study, the independent variables consist of age, working experience and estimated hand–arm vibration exposure A(8) while the dependent variables is hand numerical scoring for each hand. Artificial neural network architecture has been developed and applied to the randomized onsite data collection. The artificial neural network will be based on the feed forward back propagation network using “tan” sigmoid activation function. The results of predicting the hand–arm vibration effect were evaluated by using mean square error and regression for both hands. Both hand prediction models were produced less than 0.1 relative error of prediction as compared to actual data. Our conclusion has been that the developments of prediction model have archived the best validation and more efficient means using nonlinear techniques, hence providing health welfare among grass cutter worker against hand–arm vibration syndrome.

The Study on Whole Body Vibration Exposure Induces Low Back Pain among Uthm Bus Drivers

Buses are one of the important public transportation in Malaysia and commonly important for the student in any university. Thus, the study about Whole-Body Vibration (WBV) exposure induces to Low Back Pain (LBP) among the Universiti Tun Hussein Onn Malaysia (UTHM) was done. The objective was determine whether the bus drivers in UTHM would exceed the exposure action and limit values from the ISO 2631-1 (1997) during the working hours. Data collected according to different type of buses and evaluated the vibration significant different between buses based on the subjective correlation due to WBV questionnaire analysis. Analyze the prevalence of LBP based on the measurement and the questionnaire analysis. The study based on the international standard ISO 2631-1 (1997) which is related to the root-men-square (r.m.s) and Vibration Dose Value (VDV) parameter. The study covered among the bus drivers in UTHM. The measurement tools involved in the study is Larson Davis Vibration Meter (HVM 100) with Tri-axial Seat Pad Accelerometer to record data collection. The BLAZE software analyze the vibration exposure exceed the total vibration exposure according to 8 hours day A(8) value of 1.15 m/s2 and VDV value of 21.0 m/s1.75. The IBM Statistical Package for Social Science (SPSS) was used to do statistical analysis and testing involved was correlation, regression and ANOVA. Result obtained shows the A(8) and VDV was under EAV with highest value of 0.520 m/s2 and12.65 m/s1.75. The highest contribution factors by the duration to complete single trip per day (α=0.500).The further re-assess of working schedule need to be done in order to control the exposure level toward drivers. The assessment should be done for every two years.

Fatigue Life Assessment of Aluminium Alloy 6061 Specimen Using Signal Analysis Approach for Automotive Components

This paper is aimed to investigate the fatigue assessment of aluminium alloy 6061specimen, one of the widely used aluminium alloys in the production of mechanical components. The alloy possesses the ability of critical failure caused by fatigue when they are subjected to dynamic responses in automotive-type components. The specimens were prepared according to the ASTM E606 and ASTM E1820 standards which were then subjected to two types of cyclic loading amplitude modes namely constant amplitude and random amplitude. The effort is initiated by implementing fatigue data editing approach for random amplitude signal, the conventional method, the finite element method (FEM) and fatigue assessment determination through the statistical method of root mean square (r.m.s) and kurtosis. The input and edited signal acquired will be analyzed for the prediction of the fatigue damage based on the strain model approaches, i.e. Coffin-Manson, Morrow and SWT. From the results obtained, both edited and non-edited signals load display the same amount of fatigue damage to consequently decrease the analysis duration. In addition, the FEM was found to be the best approach for estimating the fatigue life. This research has finally revealed that the higher cyclic load amplitude will only diminish the fatigue life of a specimen. Furthermore, this fatigue assessment study will look forward to improve structural engineering development in monitoring components and consequently access the damage prediction variable which could later be implemented to the manufacturing industry.