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Smart 3D Nano-Printing in Automobile Industry
Published in Ajit Behera, Tuan Anh Nguyen, Ram K. Gupta, Smart 3D Nanoprinting, 2023
Automobile manufacturer Porsche has tested and developed a fully functional clutch lever mechanism for the Porsche 959 model. A lever is a mechanical device that can produce a mechanical advantage greater than unity. The lever was tested for a three-ton pressure test, and its effectiveness was checked against factory-tooled levers [52]. The 3D printed lever exhibited better performance, owing to which the manufacturer is extending this technology to create 20 more parts for the digital library of Porsche catalog mentioned in their pilot program; this will occur before extending it to other complex parts. Porsche 3D printed seats, as shown in Figure 3.11, are made of polyurethane material, and they can be customized as hard, medium, and soft based on a firmness level. The manufacturer wanted to extend 3D printing of 40 more seat prototypes for their racing cars, and a street-legal model is yet to be developed by 2021. They wanted to perform seat customization as per their customer's choice, comfort level, and body contours [53].
Electrical science and principles
Published in Trevor Linsley, Electrical Installation Work Level 2, 2019
A pulley is a mechanical advantage device that uses wheels, has a groove contained within its outer edge and turns freely on an axle attached to a stationary or moveable position. The pulley has a rope which is wrapped around a wheel-and-axle system which permits a user to lift heavy loads by matching or reducing the effort required regarding the weight or load in question. The greater the number of pulleys involved, the greater the number of rope parts, which basically means that the user requires less effort.
M
Published in Carl W. Hall, Laws and Models, 2018
E = 3.4 where E = Young modulus (elasticity) = density Keywords: density, elasticity, modulus McADAM, G. D., twentieth century, American engineer Sources: Fisher, D. J. 1988; Iron and Steel Inst. J. 16B, 348, 1951. See also YOUNG MODULUS MCADAMS GROUP OR NUMBER, Ma OR NMa (1933) A model for a dimensionless group or number that represents condensation for a given surface orientation: Ma = h4 L t/k3 2 g r LHc where h = heat transfer coefficient L = characteristic length dimension = absolute viscosity t = temperature, T (T is absolute temperature) k = thermal conductivity = mass density g = acceleration due to gravity LHc = latent heat of condensation Keywords: condensation, dimensionless, group McADAMS, William Henry, 1892-1975, American chemical engineer Sources: Bolz, R. E. and Tuve, G. L. 1970; Land, N. S. 1972; Layton, E. T. and Lienhard, J. H. 1988; Parker, S. P. 1992; Potter, J. H. 1967. See also DITTUS-BOELTER MCCABE--SEE DELTA LAW MACHINES, LAW OF A machine is a device in which the work output is always less than the work input, but in which either a force or speed advantage can be obtained. The theoretical mechanical advantage (TMA) is the force output divided by the force input. The actual mechanical advantage is the theoretical mechanical advantage times the efficiency, or output force divided by input force. The simple machines (Fig. M.1) are represented by: 1. Lever 2. Inclined plane 3. Wheel and axle TMA = L1/L2 TMA = D1 (incline)/Do (height) TMA = R (wheel)/r (axial)
Design-based learning to facilitate secondary students’ understanding of pulleys
Published in Australasian Journal of Engineering Education, 2022
Luecha Ladachart, Jiraporn Chaimongkol, Wilawan Phothong
A set of conceptual questions in the literature (Chini 2006; Sullivan et al. 2017) was reviewed for use in the pre-test and the post-test in this study. While these conceptual questions cover a range of scientific concepts associated with pulleys, such as force, work, potential energy, and mechanical advantage, only questions associated with force and work were selected. As a result, the final questionnaire includes 12 questions (see Appendix). Questions about potential energy and mechanical advantage were excluded or modified to focus merely on force and work because the students would need to explore a virtual simulation to understand the abstract concepts of potential energy and mechanical advantage (Gire et al. 2010). The questions were translated into Thai and sent to three physics educators to check their validity and readability. After revisions based on their comments, the questions were tested on 65 seventh-grade students in another school with similar demographic characteristics. The result confirmed that, initially, many students had misconceptions about pulleys (Myneni and Narayanan 2012), as the mean score was about 3.38 of 12, with a standard deviation of 1.49. Overall, the test seemed to be difficult as its item difficulties ranged from 0.14 to 0.37 with a mean of 0.28.
New design and optimization procedure of a 2-dof articulating mechanism for a laparoscopic surgical instrument
Published in Mechanics Based Design of Structures and Machines, 2020
Ramon Sancibrian, Esther Gonzalez-Sarabia, Sandra Robla, Maria C. Gutierrez-Diez, C. Redondo-Figuero, J. C. Manuel-Palazuelos
In order to avoid singular positions during the motion of the synthesized mechanism, a new constraint should be included in the optimization problem. Singularities refer to those configurations in which the number of degrees of freedom of a particular mechanism changes instantaneously. In other words, the mechanism is at a bifurcation point and it could take any of the two branches. Furthermore, the mechanical advantage is reduced in the proximity of the singular positions and the force transmitted through the instrument is very poor. This could lead to a low mechanical advantage and the reduction of the transmitting force. Mathematically, this situation appears when the Jacobian with respect to the dependent coordinates, Jq, is rank deficient. To avoid this problem the following constraint should be included: where is a small number. To formulate the optimization problem in a more compact way, the structural error can be grouped in one single vector. Thus, Eqs. (6) and (7) can be rewritten as follows: and the optimization problem can be formulated as, where g are the inequality constraints. The inequality constraints formulate the singularities and the size requirements for the links and the mechanism.
Dragging motion of a two-link mobile manipulator with large pull force through singular configuration: theoretical analysis and experimental verification
Published in Advanced Robotics, 2018
Takateru Urakubo, Eri Kitagawa, Xianglong Wan, Tomoaki Mashimo
At singular configurations of robot manipulators, the Jacobian matrix between the end-effector velocities and the joint velocities drops its rank, and the kinematics between them becomes singular [1]. In robot motion planning and control, singular configurations tend to be avoided due to the kinematic singularity [2, 3]. On the other hand, they may be advantageous in achieving tasks from the aspect of dynamics. In statics, it is well known that a load in a certain direction can be sustained at singular configurations without joint torques [4–8]. The advantage in statics can be theoretically explained by virtual work, and is known as mechanical advantage. For nonstatic but dynamic tasks such as moving and lifting heavy objects, it has been pointed out, only through numerical simulations and experiments, that singular configurations are useful to achieve the tasks with less torque consumption [9–11]. However, the dynamic advantage of the singularity has not been revealed theoretically yet. We have been tackling the problem of revealing it, and have theoretically analyzed the dynamic feature of singular configurations for a two-link robot arm in [12]. As a result, joint torques can generate the energy of the arm at a high rate near singular configurations, and the energy can cause a large force of pulling a heavy object. The experimental demonstration has also been achieved for a two-link robot arm in [13].