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Five Big Differences Between Electrodynamic and Servo Hydraulic Fatigue Test Machines.
TestResources offers both servo hydraulic test machines and electrodynamic test machines. The two types of test machines are functionally identical, using the same high performance 24 bit resolution test controller. Servo hydraulic technology is older - first applied to testing in 1958. TestResources first electrodynamic test machine was delivered in 2003 and is still functioning and in use performing dental implant fatigue tests and research at New York University.
1. A major difference between the two types of machines is that the load and displacement performance of a servohydraulic actuator (depending on power pack size), can be configured to deliver higher forces at higher speeds. Servohydraulic actuators can deliver loads up to 3 mN (670 kip). Low force actuators can perform tests at speeds to 200 hz.
2. The purchase, operating and maintenance costs of Electrodynamic solutions are significantly lower than Servo Hydraulic test machines. Lower force M Series linear motors perform high speed tests to 100 hz. E series actuators deliver forces to 100 kN (22 kip) at test speeds in excess of 15 hz.
3. Electrodynamic test machines all use noise free high resolution digital position encoders which deliver improved control quality and long term stability over servohydraulic test machines that use LVDT’s. Recent developments have made it possible to configure encoders on servo hydraulic actuators.
4. Competing controllers resolve data to 16 bits and TestResources controllers resolve to 24 bit, which is 256 times more than 16 bit. In addition, electrodynamic actuators are much easier to tune and much more stable in lower speed applications.
5. Servo hydraulic test machines are inherently noisy and all leak oil at some level. Electro dynamic systems are quiet and reliable.
