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Overview
Published in Sherif D. El Wakil, Processes and Design for Manufacturing, 2019
A very important fact of manufacturing science is that it is almost impossible to obtain the desired nominal dimension when processing a workpiece. This is caused by the inevitable, though very slight, inaccuracies inherent in the machine tool, as well as by various complicated factors like the elastic deformation and recovery of the workpiece and/or the fixture, temperature effects during processing, and sometimes the skill of the operator. Because it is difficult to analyze and completely eliminate the effects of these factors, it is more feasible to establish a permissible degree of inaccuracy or permissible deviation from the nominal dimension that would not affect the proper functioning of the manufactured part in any way. According to the International Organization for Standardization (ISO) system, the nominal dimension is referred to as the basic size of the part.
Cavitation in Spillways and Energy Dissipators
Published in R. M. Khatsuria, Hydraulics of Spillways and Energy Dissipators, 2004
A tolerance is defined as the range of variation allowed in a constructed dimension from the design dimension. The following three basic types of flow surface variations are present in hydraulic structures: Offset: dimension of surface irregularities perpendicular to the flow is large relative to its dimension parallel to the flowSlope: dimension of the surface irregularities parallel with the flow is large relative to the variation perpendicular to the flowUniformly distributed roughness: variation over a relatively large area. Absolute dimension of roughness element much larger than offset
Fluid Mechanics
Published in P.K. Jayasree, K Balan, V Rani, Practical Civil Engineering, 2021
P.K. Jayasree, K Balan, V Rani
Any physical situation can be described by certain familiar properties, e.g., length, velocity, area, volume, acceleration, etc. These are all known as dimensions. Dimensions are properties which can be measured. Units are the standard elements we use to quantify these dimensions. In dimensional analysis, we are only concerned with the nature of the dimension, i.e., its quality not its quantity. The following common abbreviations are used:
Crashworthiness investigation of conical tubes using dimensional analysis method
Published in International Journal of Crashworthiness, 2022
Kaibo Yan, Sisi Lu, Pan Wang, Weitao Ni, Shuguang Yao, Zhaowei Chen, Shuen Zhao
Dimension is the most basic property of physical quantity, and can be used to describe various physical phenomena. In the study of dynamic response problems for structures, to represent the value of physical quantity generally, a dimension system should be chosen first, in dimension system there is if there is a new dimension system where the magnification or minification for mass, length and time is and then in dimension system the value of physical quantity is so
The importance of equation η = μn 2 in dimensional analysis and scaled vehicle experiments in vehicle dynamics
Published in Vehicle System Dynamics, 2022
Sina Milani, Hormoz Marzbani, Nasser Lashgarian Azad, William Melek, Reza N. Jazar
Maxwell assumed a set of independent abstract base physical dimensional quantities, and expressed every other dependant physical quantity based on them. Therefore, every dependant physical quantity can be derived as a product of the base quantities, each with an exponent. The exponent indicates the dimension of that quantity. Dimensional homogeneity requires the dimension of each base quantity to be equal in every term, and on both sides of a physical equation. A dimension indicates how the numerical value of a quantity changes when the basic units of measurement change. The abstract base physical quantities in the Newtonian mechanics are: Length , Time , Mass , Temperature . A physical quantity is anything that is expressible in certain units, and completely characterised by its numerical value. Dimensions of physical quantities are all human-made concepts, as there is no such thing as a dimension in the nature. However, these concepts help science and engineering to interpret and model the nature. The concept of ‘dimensional homogeneity’ clearly differentiated ‘variable,’ ‘parameter,’ and ‘constant.’ It clarified that any term of an equation is made of a multiplication of three items: variable, parameter, constant, [3].
A study of tolerance allocation and stack-up analysis to improve the assembly precision of an injection mold
Published in Journal of the Chinese Institute of Engineers, 2023
Yuo-Tern Tsai, Kuan-Hong Lin, Chun-Sheng Chen
Tolerance is the permissible variation in the dimension of a component (hole or shaft). It is the difference between the higher and lower limits of a dimension, depending on the manufacturing capability of a machine. Allowance is the prescribed difference between the dimension of two mating parts. It is the intentional difference between the lower limit of a hole and the higher limit of a shaft. Allowance is given to the dimension of a mating part to obtain the desired type of fit. Fit is categorized into three types: clearance fit, location or transition fit, and interference fit for engineering applications. Each type of fit defines the dimensional limits to the hole and the shaft by several codes in combination.