PTC Mathcad Research Articles

MECHANICAL STRESSES ANALYSIS IN CYLINDER LINER FOR PERKINS 1306 DIESEL ENGINE

A cylinder liner is defined as a cylindrical part that is fitted inside the engine block to form a cylinder. It is a vital component of cylindrical engine. The most important functions of cylinder liner are to form a sliding surface for the piston to obtain a smoothly reciprocating motion, resist the wear form the piston and piston rings and sustain high pressure and high temperature. However, continuous exposure to high thermal stress, mechanical stress and friction inside combustion chamber may cause failure and reduce cylinder liner life cycle. Therefore, the main objective of this research is to study the stresses due to action of gas pressure, major thrust force of the piston, and thermal load in wet cylinder liner of Perkins 1306 diesel engine as a real case. Two materials namely cast iron, grades C4 28-48 and cast alloy steel, C4 35-56, grade 38XMIOA with three different thicknesses (t1= 13.13, t2= 9.2 and t3= 6.93) mm are considered. The finite element package ANSYS (19.1) has been used as a numerical method to calculate the stresses and deflection in 3D liner model for the three parts of cylinder sleeve. The PTC MATHCAD 4 is used to formulate the analytical solution of the selected case and the results are compared to the numerical results obtained from ANSYS. The numerical results show that the maximum deflection occurs at a point of applied piston load in which it is 0.135 mm for cast iron and 0.109 mm for steel. The deflection in circumferential is very small varied in range (-0.9 to 0.9) % of maximum deflection, and the maximum axial deflection for cast iron and steel are 0.66 mm and 0.67 mm, respectively. In addition, confirming the reliability of developed PTC MATHCAD 4 program by consider one verification case. These results show that a good agreement between the numerical and analytical methods.

Influence of coolant flow rates on the heat exchanger parameter at variable operation modes

Introduction. Being used in various industries, heat exchangers most often work under conditions of variable coolant flows and temperatures. At the same time, the existing theories of calculating the heat exchanger operation modes are based on the use of constant unitless parameters at any operation mode. Taking into account the effect of coolant rates on the heat transfer coefficient of the heat exchangers, the given relations are bound to specific types of heat exchangers and can only be used at constant coolant temperatures. The purpose of this study is to obtain expressions for determining the effect of coolant flow rates on the variable heat exchanger parameter.
 Materials and methods. The main variable operation modes for water-to-water heat exchangers used in heat supply systems are determined. Using simulation in the PTC Mathcad software, dependencies describing the change in the heat exchanger parameter for all the considered variable operation modes are defined. This made it possible to obtain a general formula for the change in the heat exchanger parameter for varying coolant flow rates. Coefficients in this formula take into consideration the effect of coolant temperatures, which cannot be known when calculating variable conditions, especially when the interconnected heat exchangers are operating.
 Results. To test applicability of the existing relations describing the change in the heat exchanger parameter and of obtained formula, a large number of heat exchangers is calculated at variable operation modes. Comparison with the simulation results shows that the correlations of heat exchanger theories work well at the mode with constant coolant temperatures only, while their use at other operation modes can lead to large calculation errors.
 Conclusions. The obtained formula allows finding the effect of coolant flow rates on the variable heat exchanger parameter. The formula can be used to predict the operation modes of large systems including a large number of various-type heat exchangers.

К оценке динамической прочности на волнении безопорных подробных моделей судового корпуса

Cross-disciplinary CAE-based calculations of ship movement and strains in fluid, at launching device, during ice interaction or in case of a navigation accident require very performant computers, and their results can neither differentiate specific movement shapes nor be checked by means of a physical experiment, so their verification is a very important task. Automated algorithms based on common assessment procedures for movement components and external forces made it possible to not only verify numerical calculations of apparent dynamics, but also to obtain justified and rational layouts for arrangement of external load monitoring sensors, as well as to refine these common procedures as a separate field of studies and use more accurate estimates of external forces in design algorithms. The task is to correctly transfer the obtained information on movement and pressure fields to the analytical model under straining. The model is support-free, so kinematic conditions must be imposed on it so as not to distort realistic stressed state. In the unsteady formulation, it is necessary to correctly consider inertial and damping properties of fluid and structure itself, ensuring correct transition to the quasi-static formulation. Computer-based algebra of PTC MathCAD software made it possible for the authors to develop software modules for three-dimensional motion calculations of ships with arbitrary hull shape and loading, as well as APDL ANSYS applications for applying the data on external loads in stress-strain state calculations of support-free FE model of ship in frequency and time domain. The authors managed to develop a viable open-source solution for a cross-software system meant for dynamic strength analysis of ships in waves, which can be upgraded by non-programmers.

РАЗРАБОТКА АЛГОРИТМА ПОИСКА УРОВНЕЙ НАПРЯЖЕНИЙ В КОНТРОЛЬНЫХ УЗЛАХ, ОБЕСПЕЧИВАЮЩИХ СНИЖЕНИЕ САЛЬДО-ПЕРЕТОКА АКТИВНОЙ МОЩНОСТИ В КОНТРОЛИРУЕМОМ СЕЧЕНИИ

The article deals with the development of a search algorithm of voltage levels and transformation coefficients of measure points under which the increased value of the net power flow of the active power reduces in the controlled section that allows to minimize the volumes of introduced restrictions of power supply. METHODS. The algorithm is based on electric mode optimization by the reduced gradient method featuring the target optimization function represented by the function that reflects an inadmissible exceedance of the active power flow balance in the controlled cross-section. The algorithm is implemented in PTC Mathcad. RESULTS. On example of the model of a six-node electric network synthesized in the PTC Mathcad we showed a 3.64% reduction in the active power flow balance through the use of the developed algorithm. CONCLUSIONS. It has been found out that voltage regulation in the measure points allows to reduce the values of the active power flow balance in the cross-section and minimize the voulumes of introduced restrictions of power supply required to enter the active power flow balance in the range of permissible values.

Design optimization of CAD model

This paper demonstrates the optimization process of a CAD model using the results of CAE Simulation result and computation in MathCad as an integrated approach. MathCad is generally used for calculations that take input from either dimensions of the CAD model or user defined parameters in CAD environment of Creo. The technique described here links the Creo Simulation result as the input in the PTC MathCad, while the output of this program is again directed to Creo Parametric and using this output result the CAD model is optimized. This process is a seamless integration of CAD model, CAE result and a MathCad computation using CAE results. To demonstrate this technique a mirror (used in space telescope) is selected and the aim is to find out the optimum location of mounting points that give minimum surface figure distortion under gravity loading. To check the trueness of this result, it was reviewed against the theoretically calculated values and it was observed that the optimized result was similar to the theoretical one.

Hydrogen Production From Palmitic Acid Through Autothermal Reforming: Thermodynamic Analysis

This work studies thermodynamic analysis of hydrogen production via autothermal reforming of palmitic acid. A Gibbs free energy minimization method was applied to analyze thermodynamic of syngas production via oxidative reforming of palmitic acid. Equilibrium compositions were estimated at temperature of 800°C, 900°C and 1000°C under atmospheric pressure. Optimal operating temperature and molar feed ratios of; steam to palmitic acid (S/C) and oxygen to palmitic acid (O/C) ranging from 0.5 to 4; were determined. The PTC Mathcad Prime 2.0 is used to calculate enthalpy, entropy and Gibbs free energy. Aspen Plus program was applied for calculation of product yields and heat duty. Maximum yield of 17.88 mole/molePalmitic with S/C of 4 and O/C of 0.5 can be achieved at 1000°C and yield were 7.75 mole/molePalmitic with S/C of 4 and O/C of 4. Production of hydrogen and carbon monoxide increased with increasing temperatures.

Deconvolution and simulation of thermoluminescence glow curves with Mathcad

The paper reports two quite general and user-friendly calculation codes (called TLD-MC and TLS-MC) for deconvolution and simulation, respectively, of thermoluminescence (TL) glow curves, which have been implemented using the well-known engineering computing software PTC Mathcad. An advantage of this commercial software is the flexibility and productivity in setting up tailored computations due to a natural math notation, an interactive calculation environment and the availability of advanced numerical methods. TLD-MC includes the majority of popular models used for TL glow-curve deconvolution (the user can easily implement additional models if necessary). The least-squares (Levenberg-Marquardt) optimisation of various analytical and even some non-analytical models is reasonably fast and the obtained figure-of-merit values are generally excellent. TLS-MC implements numerical solution of the original set of differential equations describing charge carrier dynamics involving arbitrary number of interactive electron and hole traps. The programs are freely available from the website http://www.physic.ut.ee/~kiisk/mcadapps.htm.

49A Development of a centralized data management and computing resource at a large academic clinical research center

This chapter will give you detailed information about many of the PTC Mathcad settings. With this information you can make informed decisions as to what setting should be used for your situation.This chapter will discuss each setting in the order it appears along the ribbon. The changes you make on the ribbon will only be effective for the specific worksheet. Each worksheet may have different ribbon settings. Refer to Chapter 17 to see how to set default settings for all future worksheets. After you become more familiar with PTC Mathcad you can refer back to this chapter to review the different settings. Previous chapters have touched on several of the topics covered in this chapter. Much of the information here is taken directly from the PTC Mathcad Help Center with additional comments added.