Apparatus and associated methods relate to a biased engagement relationship between an end cap and a support base slidably disposed within the elongate enclosure of a luminaire. In an illustrative example, the end cap may be in a fixed relationship to an open end of a translucent elongate enclosure that extends along a longitudinal axis. In some examples, the enclosure may house an LED light engine mounted to the support base. A spring may provide, for example, biased engagement relationship between the end cap and the support base over a predetermined range sufficient to prevent direct force transfer between the end cap and the support base over operating temperature ranges and/or vibration profiles. Some embodiments may dynamically damp vibrations of the support base within the enclosure, while providing for differential expansion and contraction of the enclosure and the support base, for example, over a wide temperature range.
