Load it to the limit, cycle it to the life.

Because strength and life are two different questions, and most parts fail on the second one. A static test pulls a specimen once to find its ultimate strength — useful, but it does not tell you what happens when the part is loaded and unloaded a few million times in service, at stresses well below that ultimate. That repeated loading grows tiny cracks from flaws, edges and stress concentrations until one propagates and the part fails — fatigue — and it is the dominant failure mode for aircraft structures, rotating machinery, vehicle components and almost anything with a service life. A fatigue test reproduces that cyclic loading under control, counting the cycles to crack initiation and failure at different stress levels to build an S‑N curve, or measuring how fast a crack grows (da/dN). That is the data a designer needs to set inspection intervals and a safe life. A servo-hydraulic machine does both on one frame: the static test for strength, and the fatigue test for the life — which is usually the number that actually governs the design.

Servo-hydraulic is what lets you apply large, fast, precisely-controlled loads — and the control is what makes the test valid. A servo-hydraulic actuator can produce very high force and reverse it many times a second, which is exactly what fatigue testing needs; but raw force is not a test. The value is in delivering the exact load history — the right amplitude, mean level and waveform — and holding it cycle after cycle for millions of cycles. That is a closed-loop control job: a fast servo-valve meters oil to the actuator, a load cell and extensometer measure what the specimen actually sees, and a digital controller continuously corrects the drive so the measured load matches the command. If the controller cannot keep up, it clips the peaks or lets the mean drift, and the specimen is quietly under- or over-tested — giving a fatigue life that is wrong. So the actuator and power pack provide the muscle (both of which we make ourselves), while the bought-in servo-valve and controller, integrated properly, provide the precision. Getting that loop right is the heart of a trustworthy machine.

A great deal — they are often what separates a good fatigue result from a meaningless one. A fatigue or tensile specimen is meant to see a pure axial load, evenly across its section. If the load frame flexes under load, or the grips hold the specimen even slightly off the load line, the specimen also sees an unintended bending stress on top of the axial one — and because fatigue is exquisitely sensitive to peak local stress, that bending makes the measured life come out low and badly scattered, and it is not repeatable from lab to lab. So a serious machine is built on a stiff, heavy load frame that barely deflects, with columns and actuator precisely aligned and grips designed to load concentrically; alignment is checked and certified to standards using a strain-gauged verification specimen. This mechanical foundation is unglamorous but decisive, and it is exactly the kind of precision structural and hydraulic engineering Neometrix does — the frame and the grips are as much the product as the actuator.

They are related but separate machines, and the difference is what is being tested. Our servo-hydraulic actuator test bench tests the actuator itself — there the hydraulic actuator is the specimen, and the bench proves its performance. On this machine it is the opposite: the actuator is the tool that applies load to a material or structure, which is the specimen. Our torsion fatigue machine twists a single specific shaft in torsion; this applies axial tension/compression load to coupons, components and whole structures. And our vibration & shock test system reproduces a broadband vibration spectrum on a shaker to qualify a product against its dynamic environment; this applies a controlled load or displacement history to measure strength and fatigue life. In short: the actuator bench tests actuators, the torsion machine twists a shaft, the shaker qualifies a vibration environment, and this fatigue & structural system measures how strong a material or structure is and how long it lasts under load. They complement each other, and we build all of them.

Yes — that is the structural-test end of the same discipline. A material coupon on a single frame tells you the properties of the material, but certifying a real part means loading the part the way service will. For that, several servo-hydraulic actuators are arranged around the component or airframe section and driven in coordination by a multi-channel controller, each applying its share of the load so the whole structure sees a realistic combination of forces — a static proof and ultimate test to show it carries the design loads with margin, and a full-life fatigue test that applies a representative flight-by-flight or duty load spectrum for the equivalent of a service life, with inspections for cracking along the way. This is how airframe structures and major components are certified. It draws on the same building blocks as the coupon machine — our actuators and power packs, servo-valves, controllers and load measurement — scaled up and coordinated, with the rig, reaction structure and fixturing engineered to the specific part. We size that from a single-actuator frame up to a multi-actuator structural rig according to what you need to certify.

More of this machine is made in-house than most test systems, because its heart is hardware we already manufacture. Neometrix builds servo-hydraulic actuators and hydraulic power packs as its own product lines, so on this machine the actuator, the power pack, the load frame, the grips and fixtures, and the controls are our engineering. What we bring in are the specialist precision items best sourced from established makers: the high-response servo-valve, the digital closed-loop controller, and the calibrated load cell and extensometer. We integrate those into the frame and actuator, align and verify the machine to standard, and commission it against your acceptance tests. That split — our own actuator and pump and frame, plus bought-in valve, controller and transducers — is the honest picture, and it is a stronger in-house content than an integration-only build. To be plain about status: this capability is offered turnkey and quoted against servo-hydraulic fatigue and structural test requirements; no specific delivered machine is claimed on this page.