Online Journal of Mechanical Engineering <p>Online Journal of Mechanical Engineering(OJME) is an international journal dedicated to the latest advancements in mechanical engineering. The goal of this journal is to provide a platform for scientists and academicians all over the world to promote, share, and discuss various new issues and developments in different areas of mechanical engineering.</p> en-US Online Journal of Mechanical Engineering Estimating Ultimate Shear Strength from Ultimate Tensile Strength of Aluminum and its Alloys for Blanking or Piercing <p>In pressworking, large forces cut or deform a material, and specific shearing processes include blanking and piercing of metals, including aluminum. The force requirement is directly proportional to the ultimate shear strength, USS, of the sheared material. Nevertheless, shear strengths are not readily found in engineering references, especially for the multitude of aluminum grades and tempers. Thus, USS is often estimated from some percentage of the ultimate tensile strength. However, analyses for these estimates are lacking, and it is not clear how accurately the USS is predicted. In this review of 197 aluminum alloy data, it is shown that 60% of the ultimate tensile strength provides a satisfactory estimation for USS as the predicted shear strength is, on average, within 5.5% of the actual value. USS of weaker grades, as well as for all annealed material, tends to be underestimated while the strongest grades are overestimated. The availability of reliable aluminum shear strength data makes for more efficient pressworking.</p> Robert Tatara Copyright (c) 2021 Online Journal of Mechanical Engineering 2022-11-07 2022-11-07 37 41 Evaluation and Analysis of Noise and Vibration Exposure Level On Operator of QT40B, QTJ4-40, Lister and LM2-45 Block Moulding Machine High levels of occupational noise and vibration remain a problem in all regions of the world. In Nigeria, 12-15% of the workforce are exposed to this hazards by WHO, 2001. This research intends to achieve the following objectives; To assess the noise emitted during the moulding of various types of blocks, to determine the level of vibration induced to workers of block moulders during activities and to determine the effect of noise and vibration on workers. The following materials and equipment were used; QT40B manual block moulding machine, LM2-45 Mobile Block moulding Machine, Lister powered block moulding machine, QTJ4-40 block moulding machine using 9 and 6 inches Plates, Vibrometer and Noise monitor. The workers were exposed to noise levels above 75dB and vibration levels above 5ms-2 set as upper limit values in the Directive 44/EC from 2002 – on the Minimum Health and safety Requirements Regarding to Exposure of Workers to the Risk Arising from Physical Agents Vibration. J. D Amine Sampson Chisa Owhor Milkail Alhaji Abdulkareem Copyright (c) 2021 Online Journal of Mechanical Engineering 2021-08-12 2021-08-12 1 9 Development of Cellulose Nanofibre (CNF) Coating on (1) Metal Surface for Free Standing CNF Film and (2) Paper Substrates for CNF Barrier Laminates <p>Paper is widely used in packaging applications and is biodegradable and therefore perfectly safe as green packaging wrap for the environment. The hydrophilic nature of cellulose fibrils limits the water vapour and oxygen barrier properties of paper. To mitigate these limitations, paper is often associated with other materials, such as plastics, wax and aluminum, for achieving their good barrier properties. However, these materials suffer from serious environmental issues, as difficult and inefficient to recycle. Recently, cellulose nanofibre (CNF) based materials has been considered as an alternative to produce eco-friendly barrier materials. Existing techniques to prepare cellulose nanofibre films/sheets/composites/ laminates on the paper substrates are commercially not feasible and expensive. Therefore, other cost effective and readily implementable methodologies are required to achieve cellulose nanofibre barrier layers. In the present report, a novel approach is developed using spray coating technique to produce CNF materials with excellent barrier properties. Among many coating techniques, the spray coating has many advantages such as the production of even coating surface on the base sheet and contactless coating with the substrate. A laboratory scale spray coating of cellulose nanofibre suspension on a paper substrate was developed. When the cellulose nanofibre suspension concentration was varied from 0.5 to 1.5 wt. %, coat weight is increased from 2.9±0.7 to 29.3±6.9 g/m<sup>2</sup>. As a result, the air permeability of composite was decreased 0.78±0.17 to &lt;0.0030 µm/Pa.s. Scanning electron microscopy studies of spray coated CNF laminates on the paper confirms that the surface pores in the paper substrates are filled with sprayed cellulose nanofibre and forms a continuous film on the surface of the substrate. These are the probable reasons for the reduction of air permeability of composites. A rapid preparation technique to prepare free standing cellulose nanofibre films/sheets was also developed using a bench scale spray coating system. Cellulose nanofibre suspension with concentration ranging from 1 to 2 wt% was sprayed onto a stainless steel plate, which is moving on a conveyor at a velocity of 0.32 cm/sec and then air dried. The basis weight of produced cellulose nanofibre films is varied from 52.8±7.4 to 193.1±3.4 g/m<sup>2</sup>. Processing time taken to prepare films was approximately 1.0 min, which is much less than processing times reported in the previous literature. Thus, the significant reduction in preparation time for producing the cellulose nanofibre sheet recommends that this spray coating technique can be utilized for the development of a scalable process for the fabrication of various cellulose based nanocomposite. Therefore, the laboratory scale spray coating confirms that the spraying could provide a platform for development of films/sheets/nanocomposite and also a CNF barrier layer on the base sheet. The future work is the development of a continuous spray coating of cellulose nanofibre on the base sheet and evaluation of mechanical and barrier properties spray coated barrier layers on the base sheet.</p> Kirubanandan Shanmugam Copyright (c) 2022-06-28 2022-06-28 10 36