Testing At Transtex: Experimental Modal Analysis
Have you ever wondered why our brackets are positioned where they are along our aerodynamic skirts? Well, it wasn’t by random selection! Transtex engineers always go the extra mile to ensure that every inch of our product, brackets included, is tested rigorously for optimal stability on the road.
So let’s go back to our original question: why are brackets positions where they are along the skirt panel? Consider the purpose of the bracket; not only is it meant to attach the skirt to the trailer, it is also meant to stabilize the system under all road conditions. This allows it to withstand road vibrations, thus improving the endurance and life expectancy of the skirt.
Transtex tests the aerodynamic skirts using the Experimental Modal Analysis to determine the natural frequencies of the structure. This allows our engineers to detect the optimal bracket placement locations across the panel.
Experimental Modal Analysis is the study of the dynamic properties of an object under vibration. In other words, it is a non-destructive test method that studies how an object responds to a changing amplitude of vibrations. To conduct the Experimental Modal Analysis, an impact hammer with a force sensor at the tip is placed on one side of the skirt to create the necessary vibrations. An accelerometer is attached to the opposite side to measure the amplitude of the oscillations, i.e. the back and forth movement of the skirt. The impact hammer then moves, or “roves,” across the skirt panel following a predefined pattern that is based on computer analysis.
During a road test, Transtex measures the critical oscillation frequencies using the accelerometer. The roving hammer test determines the critical and natural oscillation frequencies of the skirt panel allowing our engineers to locate the optimal placement for the brackets, thus increasing the maximum road life span of the skirt panels.