How Simcenter Amesim helps you design and optimize hydraulic systems

The Simcenter Amesim Hydraulic library is widely used by the customers especially in the automotive, oil and gas and mechanical industries. As a multi-physics tool Simcenter Amesim allows users to create systems based on hydraulic components on which can be added other types of components such as mechanical, signals or electrical for instance.

By combining all these components Simcenter Amesim offers customers the possibility to build and design hydro-mechanical systems such as pumps, control valves, hydraulic suspensions and so on.

 

Hydraulic jack design with Simcenter Amesim

In order to illustrate the capabilities of Simcenter Amesim for hydraulic system design we are going to use a hydraulic jack as an example. Here is shown how a double effect hydraulic jack is simply represented in Simcenter Amesim.

 

The hydraulic and mechanical components represented on this sketch have been chosen from the Hydraulic and the Mechanical libraries with respect of the wanted design of the system.

 

Indeed, for this example of a hydraulic jack several types of hydraulic actuators are available and depending on the actual physical system you are able to pick the one that closely represents it.

 

The picture below shows the different types of hydraulic jacks between which you can choose:

These hydraulic actuators models are all functional models that can also be modeled on a further approach using HCD (Hydraulic Component Design) in order to get a more advanced physical representation.

 

Once all the components have been dragged and dropped on the sketch to create the desired system the next step is the choice among several submodels. The submodels of a component represents in other words the level of complexity of the physics used to model this component. If you take as an example the mass you can notice that there are three different submodels available. Usually the level of complexity increases as you scroll down in the list.

Now that the system is built you need to set the components with parameters such as geometric parameters, initial pressures or displacement in case of a hydraulic jack for instance:

These parameters can either be obtained from the manufacturer datasheets, by measurements or calculations (analytical equations) if it is a conceptual design for example.

 

Now the model is ready to run the simulation and proceed to post-processing.

 

Once the model has run you can visualize along the time the variables of each components using the plots just by dragging and dropping on the sketch each variables you want to see.

Plotting the variables is one of the ways that allows you to check if the system is responding properly and to proceed to the needed changes if not. But plots can also be used to compare different designs. The variables that are usually plot for hydraulic components are pressure, pressure losses, flow rates (or velocity).

 

Simcenter Amesim offers you a Study Manager that enables you to easily and quickly create batch study simulations in the aim of comparing several configurations of your system.

 

Here is an example of study settings for our hydraulic jack system:

Using a batch study allows you to realize parametric analysis in order to determine the influence of the variation of some of the parameters of your system.

 

In the frame of this hydraulic jack example we have compared the piston displacement along the time with respect of the piston diameter. If you plot all the results on the same graph you are able to see precisely which configuration reaches your expectations and the design that suits you the best.

This just a starter example on how Simcenter Amesim can help you in the design of a hydraulic jack. Nevertheless if you take this hydraulic jack model as a base you can switch to a slightly more complex example that shows how Simcenter Amesim can be useful for hydraulic systems optimization.

 

Want to see how it works? Watch the movie:

 

 

 

 

 

How to optimize hydraulic systems Simcenter Amesim

 

At an early stage of the development hydraulic system designs are not quite optimized especially in terms of pressure levels, flow rate distribution and energy consumption. Basically hydraulic components are assembled to build the system and then tested to check if the system works properly. When the system functioning has been validated you can now proceed to the optimization of the performances of this system. Here is the system that we used as an example. The first step is to verify if all the requirements that you have defined at the beginning are fulfilled.

 

 

In this case the requirement for the pressure level at the pump outlet was not to be higher than 5 bars but when you check out the results.

The maximum pressure reached is 30.10³ bars which is way beyond the expected value. The system then needs to be improved in order to keep that pressure value under 5 bars. The easiest solution is to add a pressure regulation system. To do so a pressure relief valve is added in parallel of the volumetric pump in order to regulate the pump outlet pressure at the required value.

 

 

Before adding the pressure relief valve in order to regulate the pump outlet pressure you have noticed that the pump was capable of providing a lot pressure at the outlet. However what you have to keep in mind is that to provide 5 bars or way more at its outlet the pump consumes the same amount of energy. Which means that energy is wasted when a pressure regulation is used in the system.

What solutions do we have to prevent this waste of energy and then optimize the power consumption?

 

In fact there are many solutions that can be used such as reusing the surplus of pressure to feed other systems, using a piloted variable displacement volumetric pump (a pivoting or a sliding vane pump for instance) in order to adapt the outlet pressure or using a variable electrical motor.

For the purpose of this demonstration the third option will be used. Nevertheless other demos available in Simcenter Amesim Help documentation can show you how to implement the other options.

 

Here is presented how to add a control on the pump actuation:

Basically in this system power is wasted any time the system gets static. Which means that any time that hydraulic jack won’t move or reach one or the other end stops power will be lost as the pump won’t be necessary.

 

What this actuation control does is that it senses the hydraulic jack displacement and sends this information to the electrical motor so that the pump can be stopped every time that it is not needed.

This example is also a relevant way to show how multi-physics can be used in Simcenter Amesim for hydraulic systems optimization.

 

Watch this short demo to see Simcenter Amesim in action: