Fluid Power Research Update: High Pressure Compliant Material Development

We’ve written before about the Center for Compact and Efficient Fluid Power (CCEFP)—the network of fluid power research laboratories, academic faculty, graduate and undergraduate students at seven universities—that is making a difference when it comes to preparing a better educated workforce for the fluid power industry. The CCEFP has created a 500% increase in the number of fluid power focused advanced degrees awarded in the United States, with almost half of its graduates going on to work in the fluid power industry.


In addition to increasing interest in fluid power, the CCEFP has also been home to a number of research projects in fluid power. One such project involves investigating high pressure compliant material development.

High Pressure Compliant Material Development

by Elliott Gruber, PhD Candidate, Georgia Institute of Technology

Figure 1.  Suppressor with voided polymer liner

Figure 1. Suppressor with voided polymer liner

A new type of lined noise suppressor is under development for the hydraulics industry. Noise near operating hydraulic machinery is often uncomfortable, disruptive to communication and can reach levels hazardous to hearing. The noise is caused by pressure fluctuations within the working fluid, known as fluid borne noise (FBN), which has several other detrimental side effects such as machine vibration and leakage. A method to reduce the FBN is to include a suppressor with an annulus of voided polymer within the system. The voided polymer is known as a syntactic foam liner and the entire device, shown in Figure 1, is called a liner style suppressor.


Figure 2 Fluid borne noise with and without lined suppressor

The voided polymer is extremely soft in comparison to the hydraulic fluid, which reduces the transmitted pressure ripple through the device, as seen in Figure 2, without significantly affecting the functionality of the system. The syntactic foam primarily derives its softness from the relative size of the engineered voids within the foam. As operating pressure increases the voids shrink and the foam becomes less effective at treating noise. The existing material within such a suppressor effectively treats noise up to a system pressure of approximately 70 bar (1000 psi); however, many hydraulic systems operate at pressures up to 345 bar (5000 psi). In general, higher system pressures produce more FBN and the associated problems are more severe, making it important to treat the FBN at these pressures. The existing formulation of a syntactic foam liner can be improved by increasing the initial internal pressure of the void to increase its volume over all working pressures and therefore its noise control effectiveness.

For more information and further discussion, you can reach Elliot Gruber at e_gruber@gatech.edu or you may also contact the advisor to the project, Professor Ken Cunefare, at ken.cunefare@me.umn.edu.

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