![]() ![]() The more usual methods of damping, however, are the use of a special material or fluid in series or in parallel to the applied load, the reaction time(s) of which are out of phase with the system. These are the most complex damping methods and tend to be reserved for expensive and sensitive equipment. when amplification is detected the mass/support can be slid in either direction, thereby altering its natural frequency. An example of such a design for, say, a beam ( Fig 3) would be to apply a sliding mass or guide support anywhere along the beam’s length that can be repositioned during operation according to pre-defined conditions. that may be adjusted during operation to modify an element's natural frequency. Shock Absorption: This is the slowing down of the applied load and/or its release, thereby reducing its dynamic amplification factor (see CalQlata’s Shock Load calculator) and hence the load(s) and deformation(s) in the system.įrequency Shift: This is the altering of a system’s natural frequency away from its operating frequency ( Fig 3). The normal solution to this problem (resonance) is to reduce (or dampen) the effect of the dynamically applied cyclic load by shock absorption, however, shifting the natural frequency of the element also works particularly well. to a different frequency)Ģ) Altering the stiffness of the sprung systemģ) Altering the location of the repeated loadĤ) Reducing the magnitude of the repeated loadĥ) Reducing the dynamic amplification of the repeated load Vibration damping is the reduction or avoidance of resonance and can be achieved by any of the following actions:ġ) Altering the natural frequency of the sprung system (i.e. For example:Īs can be seen in Shafts Fig 2, any value within the range 0.86 1.3 produces the opposite benefit and disadvatage in that transitional resonance will always occur but amplitude magnification will normally be less than 1 rubber), between the mounting frame and floor or base to dampen vibrations.Įach position ( 1, 2, 3 and 4) will have a different natural frequency (ƒⁿ) and must be selected to avoid coinciding with the operating frequency (ƒ) of the vibrating equipment ( Fig 2) see Support Positioning below. ![]() As can be seen in Fig 2, the amplitude magnification (Mᶠ) of an undamped (ζ=0) element operating at its natural frequency could become infinite.įig 1 shows the options available for positioning supports on a typical sprung system using a special material (e.g. Thus a force applied at an element’s natural frequency will generate a different deformation than would be expected from a static load (see Damping Ratio below). When it is subjected to a cyclic load close to its natural frequency the resultant deformation will not be as expected, because at this frequency the element’s own mass and motions will influence deformation. The stresses and strains induced in an element are totally predictable if it behaves exactly as expected, however. ![]()
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