Engineering Formulas Research Articles

Prediction of Brake Pad Wear of Trucks Transporting Oversize Loads Based on the Number of Drivers’ Braking and the Load Level of the Trucks—Multiple Regression Models

Brake pad wear forecasting, due to its complex nature, is very difficult to describe using engineering formulas. Therefore, the aim of this publication is to create high-quality brake pad wear forecasts based on three stochastic quantitative models based on multiple regression models (linear model, inverted linear model, and power model). The matrix of explanatory variables was extracted from the controllers of 29 vehicles: A—the driver’s style of using the brake pedal specified on a 4-point scale and B—the number of vehicle load ranges specified on a 5-point scale. Methodology: A matrix of explanatory variables was obtained over a 2-year period from trucks carrying oversize loads via OBD2 socket. The trucks operated under similar operating conditions. The created models were verified in terms of their fit to the source data and by analyzing the residuals of the models. It should be emphasized that only the linear model met all the required criteria. The inverted linear and power-law models were rejected. Results: The verified linear model is characterized by very small MAPE errors. The model was validated on 4 trucks and the brake pad wear prediction errors ranged from −0.39% to 7.03%.

Параметрическая модель синхронного реактивного двигателя с TLA-ротором в установившихся и переходных режимах

There is considerable practical and scientific interest in synchronous reaction motors (SynRM) with TLA rotor. The core of the TLA rotor has a transversal charge, internal slots, and highly saturated areas. The configuration of the rotor slots is complex and diverse. The task to develop a parametric model of the SynRM with a TLA-rotor designed for calculation of steady-state and transient modes of the motor is relevant. The classical parametric model of SynRM based on the theory of two reactions is used. The calculation method for the parameters of the SynRM model with TLA rotor is presented. The method uses the results of field calculation of two static states of the magnetic field. The steady-state conditions of SynRM are calculated according to the engineering formulas derived from the equation of equilibrium stresses in the stator phase. The Park-Gorev equations are used to calculate the transient modes of the SynRM. Field models of the SynRM under study at longitudinal and transverse rotor positions are presented. Main harmonics of magnetic field in the gap and their dependence on armature current are calculated. Formulas to calculate the inductive parameters of armature winding and performance characteristics of SynRM are given. Differential equations to calculate processes in SynRM are given. The parametric model is used to calculate performance characteristics of SynRM, frequency start process, electromechanical process of SynRM operation in case of asymmetric power supply. The calculation results are compared with the results of field simulation of SynRM with TLA rotor in the Ansys Maxwell environment. The classical parametric model of the synchronous machine based on the theory of two reactions allows fast and high-quality analysis of steady-state and transient modes of operation of a synchronous reactive motor with TLA-rotor under various conditions of power supply and mechanical load, including abnormal ones.

Hydrodynamic Analysis of Shallow Water Sloshing in Ship Chamber Under Longitudinal Earthquake

Shallow water sloshing-structure interaction under the coupled longitudinal and pitch motions resulted by the longitudinal earthquake directly affects the structural safety of the shiplift. However, no matter in shiplift or other related fields, there is little research on this aspect at present. As a basis of structural dynamics analysis and earthquake resistant design, an analytical method including a developed modal system and new engineering formulas is presented to predict the hydrodynamic moment and force in the ship chamber. Based on the linear modal theory, a modal system describing shallow water sloshing under longitudinal earthquake is developed with infinite set of modal functions. Then, new engineering formulas for calculating the hydrodynamic moment and force are proposed with only retaining the lowest sloshing mode (n=1). Case simulations suggest that the maximum error of hydrodynamic moment and force between n=1 and n=100 are lower than 1.3% and 10.5%, respectively. In addition, the hydrodynamic moment resulting from pressure on the walls can be reasonably ignored, which accounts for less than 0.5% percent of total hydrodynamic moment. With respect to the currently used Housner model, the presented formulas are greatly improved in computational accuracy and rationally supplement the missing part in the seismic design part of the Design code for shiplift.

Formula Dress

Trends in Textile Engineering & Fashion Technology Formula Dress Ivanov KG*, Ivanova EA and Deligioz AV St. Petersburg State University of Industrial Technology and Design, St. Petersburg, 191186, Russia *Corresponding author:Konstantin Ivanov, St. Petersburg State University of Industrial Technology and Design, St. Petersburg, 191186, Russia Submission: April 13, 2023; Published: April 20, 2023 DOI: 10.31031/TTEFT.2023.08.000690 ISSN 2578-0271 Volume 8 Issue3

Semi-analytical load models describing the progressive immersion of a fixed vertical cylinder in a breaking wave

This paper is part of the DIMPACT (Design of floating wind turbines and impacts of energetic steep and breaking waves) project concerning slamming loads on floating offshore wind turbines. Two semi-analytical models accounting for the progressive immersion of a vertical cylinder in a breaking wave are presented. These models are based on the rate of change of the fluid momentum and the continuity of the added mass during immersion. The first model is based on the Generalized von Kármán Model where the real shape of the body and its added mass are accounted for. To account for the nonlinearity of the flow kinematics, the second-order terms of the momentum equation are considered in the inertia load. The total load is obtained by adding the drag force using a variable drag coefficient. To better predict the slamming load, a second model based on Wagner’s theory is presented. The Modified Logvinovich Model provides the pressure distribution at the first instants of impact. It is assumed that the flow does not separate from the structure. The load models are applied in a strip-theory approach under the Froude–Krylov assumption. For comparison, a Navier–Stokes solver is used to generate four phase-focused breaking waves. The resulting free surface shape and the ambient kinematics of the two-dimensional waves are used in the semi-analytical models. The present models are compared with existing slamming load formulations and a three-dimensional numerical simulation with an actual cylinder, where the load on four sections of the cylinder are considered. The force in the deeply immersed sections is in good agreement in all models considered. In the partially submerged section, the proposed load formulations and the three-dimensional simulation predict a similar load. Other standard engineering formulas predict a much lower force in this section. In the area impacted by the crest, the Froude–Krylov-based approaches predict a much higher force than that given by the Navier–Stokes result, likely due to the free surface being disturbed by the cylinder.

Air density calculation at high altitude locations for wind energy use: the alpines validation

ABSTRACT Atmospheric air density has an essential role in the energy production of wind turbines. It is directly proportional to the power taken out from the airflow. The common practice at a planned wind farm location is to measure atmospheric parameters and calculate the air density as monthly and yearly averages based on the International Committee for Weights and Measures (CIPM). After that, the reference point is used to calibrate spatial data to study the siting of wind turbines at a large spatial domain of interest using an engineering method based on only temperature and elevation a.m.s.l. The engineering method is also employed with only temperature and elevation data when there are no pressure and relative humidity measurements. The point-to-spatial transformation is done through the simplified engineering formula, and it is known that the method is primarily valid up to a.m.s.l. Above these elevations, the engineering methods have a significant bias, up to error in estimating the air density. This bias leads to a substantial error in energy yield estimations. This study uses more than one in-situ measurement at high altitude locations to calibrate the engineering method at the Alpine Convention Perimeter. It aims to improve the calculation accuracy by calculating the pressure gradient within the region. It is found that the seasonal and yearly averaging errors can be improved by to in the air density calculation with the new approach. The method can be applied to other locations with similar conditions.

Development and Finite Element Analysis of a Cantilever Beam Apparatus used in Strength of Materials Laboratory

The development of a cantilever beam apparatus for the teaching of undergraduates students in Strength of Materials laboratory is successfully presented. This development of the laboratory apparatus is targeted at building a local content in the production of equipment. It tends to eliminate the dependence on foreign technology which appears to be challenging in the face of scarce foreign exchange. The laboratory apparatus was designed using engineering formulae to determine the maximum bending moment, maximum shear stress, factor of safety and the Von Misses stress of the beam to be749.95Nm, 11.26Mpa, 2.36 and 112.28Mpa respectively. The apparatus was designed to have a strength to weight ratio of 5.3Mpa/N. A graphical modeling was carried out using AutoCAD and Finite Element ANSYS Workbench which yielded an equivalent Von Misses stress of the apparatus to be 115Mpa. Keywords: Cantilever beam, apparatus,Von Misses stress, finite element and materials DOI: 10.7176/JIEA/13-1-01 Publication date: February 28 th 2023

Entropy optimization of Marangoni flow of hybrid nanofluid under the influence of viscous dissipation and activation energy: With melting phenomenon

AbstractAs nanotechnology and optimization develop, the demand for more effective and robust heat transfer fluids with much greater thermal conductivities than ordinary ones grows. Marangoni convection is often employed in coloring on the ground, for example, in fine art mechanisms. Melting and welding operations are the most prominent manufacturing uses of the Marangoni convection principle. This article aims to reveal the characteristics of hybrid nanofluid () and nanofluid () under the influence of Margorani convection and Entropy generation in a porous Darcy‐Forchheimer medium under melting circumstances. Viscous dispersion and activation energy's effects are also taken into account. The suggested fluid flow problem is mathematically modeled. A built‐in shooting technique algorithm tackles the dimensionless flow model. After applying suitable transformations, the governing nonlinear PDEs are reduced to highly nonlinear ODEs. The numerical outcomes of obtained ODEs are attained through the bvp4c technique built‐in MATLAB. The effects of various classes of significant parameters on the rate of heat generation and Bejan number profiles are investigated. The physical impact of the flow‐regulating constraint factors is visualized via graphical representations. The results are summarized based on numerical data compared to important engineering formulas such as surface drag force, Sherwood numbers, Nusselt, and density. In terms of final remarks, the main findings are successfully described. This article delves further into the uses of hybrid nanofluids in the primary study regions of medicine, space, ships, and defense. Some of these research areas include the automotive industry, heat exchangers coolant in machining, heat pipes, and manufacturing, electronic cooling, refrigeration, solar energy as well as applications for ventilation, heating, and air conditioning, nuclear system cooling, generator cooling, transformer cooling, and electronic cooling.

Unapređenje pneumo-hidrauličkog pojačala za mašine za presovanje - projektovanje i proračun parametara

Pneumohydraulic pressure amplifiers are widely used in mechanical engineering. Using a pneumohydraulic amplifier makes it possible to minimize the size of the presses while simultaneously multiplying their technological effort. A significant disadvantage of the classical method of force multiplication is the low speed of movement of the working bodies of technological equipment under a hydraulic drive. The article proposes a fundamentally new design of a pneumohydraulic amplifier, in which a high-speed pneumatic cylinder carries out the idling of the technological tool, and force multiplication is carried out only at the stage of the working stroke, which allows many times to increase the performance of the amplifier. This effect is achieved by using a movable hydraulic chamber. The engineering formulas and diagrams presented in the article for calculating the parameters of a new pneumohydraulic amplifier allow engineers to adapt the amplifier to various technological conditions. The economic effect when using the proposed amplifier design is achieved by multiplying the productivity of the press equipment.

Analysis on construction technology of large steel structure building thermal insulation engineering

In order to solve the need of maintaining temperature in large steel structure buildings, the author proposes a method of applying new materials, this method is used to analyze the properties of exterior insulation materials for steel structure buildings. Combining with the need of heat preservation in large steel structure cold storage, the author puts forward a new construction technology and applies it into practice by combining autoclaved gas technology, the advantages and disadvantages of organic and inorganic materials on heat preservation effect are analyzed, through the value engineering formula of maximum efficiency analysis, the minimum life cycle cost, in the ideal place, time to play the necessary function of the product. Finally, the experimental samples adopted the author?s method are compared with the ordinary samples. The experimental results show that the absolute value of indoor and outdoor temperature difference under the construction process is significantly greater than that under the current construction process, the highest temperature reached 29.2? and the lowest was 25.6?. In conclusion, the method adopted by the author can greatly help the current construction technology and reduce the loss of enterprises.

Lubrication reliability analysis of wind turbine main bearing in random wind field

This paper aims to establish a method to evaluate the lubrication reliability of the wind turbine main bearing in random wind fields. The aeroelastic simulations are conducted and the hub load is captured to generate the lubrication parameter database. Then, the lubrication reliability of the main bearing is evaluated and the effect of the random wind field on lubrication reliability is studied. Finally, an engineering formula to rapidly evaluate the lubrication failure probability for this wind turbine main bearing is obtained. Results show that the average wind speed and turbulence intensity affect the failure probability by S-shaped and linear law respectively. The lubrication of this wind turbine's main bearing almost completely fails when the average wind speed is 7 m/s.

Calculation of Optimal Length for Skyline

As important for the design of cable logging systems both theoretically and practically, the optimization problem regarding the optimal
 length of the skyline was determined. In the process of modeling the shape of the sagging curve of the holding cable, the objective function is
 constructed in the form of a transcendental equation, whose roots are determined by iterative and graphical-analytical methods. A numerical
 analysis of the problem is carried out. To calculate the optimal length of the skyline, a software algorithm, an engineering formula, and nomograms are proposed.

The Depth of the Zone of Thermal Influence of Highways

The thermal regime of road surface and basements is an important factor determining their reliable and safe operation in the cryolithozone. The aim of the research was to quantify the possibility of replacing the layered environment of the road's soil base with an equivalent homogeneous soil with an average coefficient of thermal conductivity when calculating the depth of the road's thermal influence zone. Two methods of averaging the thermophysical properties of a layered medium are considered: weighted average and arithmetic average. Dependences are obtained for determining the degree of deviation of the properties and thicknesses of the layers of the soil base, in which both methods are acceptable for engineering calculations. As an example, the two-layer medium of the road base is considered. For the analysis, the classical formula of the depth of thermal influence was used, obtained from the solution by the integral method of the one-dimensional equation of unsteady thermal conductivity. Simple engineering formulas are given for the relative error in determining the values of the depth of thermal influence when using an equivalent layer of pavement in calculations. A concrete example of calculating the depth of the zone of thermal influence in the two-layer soil of the road base is considered. The equation of the functional relationship between the parameters characterizing the degree of deviation of the thickness and thermophysical properties of individual layers from each other is obtained, which provides an error in the calculations of the depth of the zone of thermal influence less than the permissible value. The results of numerical calculations are presented in the form of 2D and 2D graphs, which allow us to visually assess the influence of the range of changes in the values of the thermal conductivity coefficients of individual soil layers on the legality of using various methods of constructing an equivalent single-layer road foundation structure.

Antropomorfni hodajući robot - dizajn i simulacija

The current stage of development of robotic systems is characterized by the use of anthropomorphic robot designs, the functions of which are as close as possible to human capabilities. This trend is explained by the need to give robots universal capabilities when performing various technological operations. The article proposes a fundamentally new design of a walking robot and describes a model of its functioning. This design allows the robot to move in an angular coordinate system, which is typical for humans. The main motivation for creating such a robot is to reduce the number of drives for the kinematic chain of the walking mechanism. The article presents the results of mathematical modeling and recommendations for the design of anthropomorphic walking mechanisms. The engineering formulas and diagrams presented in the article for calculating force loads make it possible to create various modifications of walking robots that have the property of adapting to an arbitrary surface topology for moving a mobile robot. The economic effect is achieved by reducing the number of electric motors for the robot's leg joints and, consequently, by reducing the total cost of the walking robot.

Controlling the thermal regime of the road surface in the cryolithic zone

The thermal regime of the road surface of automobile roads in the cryolithic zone determines its reliable and safe exploitation. An important indictator of the thermal regime is the thawing depth of the road foundation (the underlying soil). The purpose of this research was to determine the influence of the Biot number, characterizing the thermal resistance of the structural layers of the road, on the thawing depth of the road surface. On the basis of simple engineering formulas, the basic qualitative and quantitative regularities of the influence of Fourier and Stefan numbers on the Biot number value which allows thawing of the road foundation up to a given depth in the warm period of the year were surveyed. 3D charts allowing to determine the required Biot number in a wide range of initial data were created. Knowing the Biot number, it is possible quickly to determine the thermal resistance and to select a fitting material for the additional thermal insulation layer for the structure of the road surface.

Thermal protection of roads in the permafrost zone

The problem of choosing a method of construction of thermal protection layer of the road pavement in permafrost zone was solved. Simple engineering formulas to justify the choice of the specific type of thermal insulation structure were obtained. It was determined that a structure composed of two layers (separate layers insulant and of sand) is always more efficient than a thermal insulation mixture (combined insulant and sand) applied in one layer for the purposes of maximizing thermal resistance. At the same time, a quantitative assessment demonstrated that in many practical cases, the difference in thermal resistance of the two kinds of structures is slight and is within the margins of permissible precision of engineering calculations. For this reason, it is expedient to also consider the technological demands of application of one or the other type of thermal insulation layer in addition to the thermal resistance considerations. Formulas to find the area of rational use of thermal insulation mixtures instead of merely sand bedding were devised. It was determined that the thickness of bedding in one or the other case is significantly dependent on the ratio of thermal conductivity coefficients of sand and the insulant. In addition, the change in relative thickness of the layer can have both negative and positive values.

Rigorous Interpretation of Engineering Formulae for the Convolution and the Fourier Transform Based on the Generalized Integral

This paper aims at providing a framework suitable for justification of classical convolution integral and Fourier transform in many cases not covered by the usual definition of integral used for signal theory applications. Generalized functions approach from functional analysis is used, simplifying it to be approachable for engineers while retaining the rigor. The generalized functions approach results in an elegant and applicable definition of integral known before in the mathematical literature which is readily applicable in signal theory, justifying formulae usually seen as dubious and criticised for lack of rigor. The study offers a rigorous, simple and understandable definition of integral for use in analog signal theory, helping the formalization of engineering education by means of rigor. Main advantage of this approach is retaining the classical notation used in signal theory as well as its straightforward justification of key formulae in signal theory resulting from convolution and/or Fourier transform.

Increasing thermal stability of the roads in cryolithic zone

Automobile roads in cryolithic zone in disctinctly continental climate conditions are subject to significantly greater adverse thermal impacts, such as high diurnal temperature variations, than similar structures in milder climates. This requires higher expenses on exploitation and maintenance of the automobile roads. It is possible to mitigate these negative impacts of rapid temperature changes, reducing maintenance costs and improving safety of road use, through application of thermal protection.This contribution explores protection of road structures using materials with high thermal stability indicator within the constructive layer of the road and aims to provide tools to quickly assess the optimal concentrations of thermal accumulation filler in the thermal protection layer. Using the unconditional optimization method on the temperature conductivity coefficient of the binary mixture, simple engineering formulas were obtained to find the optimal concentration of the thermal accumulation filler. It was established that regardless of the thickness of the thermal protection layer, the optimal concentration of the filler is a constant. However, there are values outside of the optimal range beyond which the increase of filler concentration is ineffective. It was discovered that even a minimum concentration of the filler (10%) improves the thermal stability indicator twice, and at the optimal concentration of 44% there is a threefold increase in thermal stability. The formulas and their results are visually presented in the form of charts, allowing to grasp the range in optimum concentrations of thermal accumulation fillers to achieve the highest thermal stability effects.

Engineering formulas for dimensioning of deformation and damage zones in jointed rock mass under impact of blasting in quarries in Transbaikalia

Currently, there are five characteristic zones of blast-induced impact in quarries: crushed zone, radial cracking zone, severely fractured zone, blast-induced residual stress zone, and blast-induced load zone. Knowledge about the size of the zones is very important in the technological processes of mining. The size of the crushed zone governs the amount of ore over-grinding and loss. The size of the radial cracking zone is reflective of the spacing of blastholes. The size of the severe fracturing zone is characteristic of the geometry of an unstable pit wall area. The zone of blast-induced residual stresses in rock mass and its size affects the slope stability of pit wall. The purpose of this study is to develop engineering formulas for calculating the sizes of deformation and damage zones in jointed rock mass during short-delay blasting in quarries. The mathematical and numerical analyses of the complex theoretical expression provided engineering formulas for dimensioning of the blasting-induced impact zones in quarries. The reliability of the formulas is proved by the comparison with the full-scale testing data obtained in quarries in Transbaikalia.

An efficient simplified elastic–plastic analysis procedure using engineering formulae for strain-based fatigue assessment of nuclear safety class 1 piping system subjected to severe seismic loads

This paper proposes an efficient simplified elastic–plastic analysis procedure using engineering formulas to perform strain-based fatigue design considering the plasticity that occurs in nuclear safety class 1 piping systems during severe seismic loads, and then presents the application results of the procedure to a pressurizer surge line system. The total strain amplitudes, fatigue assessment results, and total calculation time were compared between the proposed procedure and the detailed dynamic finite element elastic-plastic analysis. The comparison confirmed that the proposed analysis procedure can efficiently derive reasonable and conservative results for nuclear safety class 1 piping systems under severe seismic loads.