Lumped Parameter Libraries (0D)
Component libraries are collections of parametric models that are specialized on the demands of a certain domain e.g. hydraulics or pneumatics.
Hydraulics
The DSHplus hydraulic library covers all the usual components necessary for building a hydraulic system. By sticking close to ISO 1219-1 the graphical representation looks entirely familiar to the fluid engineer therefore keeping things clear and offering didactical opportunities by using the animation option.
Subsections for pumps, motors, cylinders, control-, flow- and pressure valves as well as accumulators, lines and pipes help to sort things and make finding the right component an easy task.
A major part of these 180+ components is modeled by mathematical functions which can be found in the widely publicized literature. Parameterization is possible by simply using manufacturer data sheets. Complete sets of a component’s parameters can then be saved in a local data base for later use in different models.
Each subsection of the library also contains physically modeled components for a detailed analysis. Should a special kind of component be missing it can either be build using several standard components or elements of the micro component library. By combining these into a submodel the new complex component can be added to the library for further use.
Pneumatics
The DSHplus Pneumatic Library comprises a complete set of pneumatic components to design and analyse a multitude of systems. The library was developed in association with the Institute of Fluid Power Drives and Controls (IFAS) of the RWTH Aachen University, an internationally recognized fluid power research center.
The Library is dedicated to support the design of complex pneumatic systems and to study their static and dynamic behavior. As with the DSHplus Hydraulic Library the calculation of pneumatic systems is based on numerically solving the differential equations for the pressure gradients.
For today's applications the simulation of pneumatic systems focusses primarily on two fields: automation technology and the undercarriages of cars, utility vehicles and trains. There, air suspensions are typical pneumatic systems, which allow for analysis by simulation. Further on a combination with DSHplus-STC and a multi-body simulation program provides vehicle models, which allow for a detailed study of comfort and driving dynamics. Other classical fields of applications for the DSHplus Pneumatic Library are mechatronic systems in the packaging and handling industry.
Mechanics
The mechanical library provides basic but effective elements to reproduce a one-dimensional oscillatory system. Calculation is based on Newton’s laws of motion and the conservation of momentum.
For mechanical systems the same systematics as with hydraulic systems are applicable: hydraulic circuits consist of alternating capacitive and resistive elements, mechanics feature masses and force related elements. In DSHplus these mass and force elements are joined by mechanical nodes, where stroke, velocity and force (respectively angle, angular velocity and momentum for rotational connections) are combined into a single connection line. Separation of these variables into single signals is always possible, either by taking the signal directly from a component’s output or by using a transformer element.
Most cases of mechanical structures allow for this one-dimensional approach, but it is also possible to combine translational and rotational motion, e.g. when a body is tilted by asymmetrical forces. This is for instance useful to examine the positioning precision when a linear guide is subject to angular errors.
Control Engineering
Our DSHplus control engineering library is dedicated to support the design of control circuits for fluid power applications. It also enables the user to graphically set-up custom component models which are not covered by other DSHplus libraries. To achieve this, all models of this library are based on the block diagram approach.
The control engineering library comprises signal sources, mathematical expressions, linear and nonlinear functions, look-up tables, switches, analog and time discrete controller elements, logical elements and user defined function blocks.
Particle and Filters
Considering the increasing complexity of hydraulic systems the design of adequate filtration concepts becomes more and more difficult. This complexity is a challenge for designers because until now the design of a filtration system has mainly been based on experience. To get better predictions and insights especially in complex hydraulic systems and different filtration concepts the DSHplus particle and filter simulation has been developed.
The new DSHplus particle and filtration simulation offers the possibility to simulate the dynamic distribution of particles inside fluid power systems. On the one hand this allows the design of an ideal filtration concept for reliable plant operation, and on the other hand it also reveals new possibilities for a virtual condition monitoring development.
The particle simulation model itself is characterised by particle sources and sinks. Particle sources can be breather filters or cylinders, that accumulate particles from the surrounding environment, and pumps and valves, that generate particles through internal component wear. Contrarily particle sinks, such as filters or reservoirs, reduce the number of particles in the system. Next to these two main component groups there are also transfer elements such as pipes, which determine the dynamic behaviour of the particle distribution within the hydraulic system. The development engineer is able to check the particle size distribution at each point of the system, thus he can keep the purity levels low at locations of sensitive components, such as servo valves. He is also able to analyze the amount of absorbed contamination in different filter elements, which leads to a better planning of maintenance intervals and results in shorter downtimes of the plant. Another application of the DSHplus particle and filtration simulation is the virtual analysis of initial cleaning procedures before the system’s commissioning.
Customer-Specific Libraries
The FLUIDON Engineering Service develops DSHplus customer specific libraries according to specific customer requirements, usually to represent the company’s products. Characteristic features of such a library are detailed component models to achieve high quality simulation results and ready to use component parameter sets to guarantee an convenient usage.
Typical areas of application for the DSHplus customer specific libraries are in house product development projects or library exchange with other DSHplus users to support customer acquisition activities.
Library for property data handling of fluids
This library is used for property data handling of fluids. The fluid properties assigned to the "Fluid" component can originate from different data sources, e.g. from
- equation-based fluid descriptions
- characteristic diagram-based fluids, which are deposited in the library
- the "Custom Fluid" component, into which the user can load his characteristic diagrams
- the equation-based description of the standard fluid HLP 46, if no fluid is defined for the model
In addition, the Bunsen coefficient (measure for the gas dissolving capacity of a liquid) and the vapour pressure curve were added as new material properties. With knowledge of the vapour pressure and the Bunsen coefficient, the pressure-dependent growth and transport of vapour and/or gas bubbles in liquid-filled piping systems can be represented.
