lengdeforskyvning

Lengdeforskyvning is a term used in Scandinavian languages to describe longitudinal displacement — the movement or shift along the length of an object or along a defined axis. It is encountered in physics, engineering and related disciplines as a way to express how much an object lengthens or shortens in response to forces, temperature changes, or other effects that act along its length.

The primary manifestations are axial extension under tensile load, axial compression under compressive load, and thermal expansion or contraction. The quantity is typically expressed as ΔL, the difference between a final length and the original length L0, with axial strain ε = ΔL / L0 describing the relative change in length.

For uniform cross-section and material, the mechanical contribution to length change is ΔL_mechanical = F L0 / (A E), where F is the axial force, A the cross-sectional area, and E the Young’s modulus. Thermal effects are described by ΔL_thermal = α ΔT L0, with α the coefficient of linear thermal expansion and ΔT the temperature change. In many problems the total length deflection is approximated by the sum ΔL_total ≈ ΔL_mechanical + ΔL_thermal for small deformations.

Applications include sizing and fit considerations in structural members, fasteners, piping, and other components where precise length changes affect performance or clearances. In geophysics and seismology, longitudinal displacement can refer to particle motion along the direction of wave propagation, though usage varies by field.

Note: lengdeforskyvning is the Nordic spelling for longitudinal deflection; related terms include längredförskjutning, elongation, and axial strain.