Structural Mechanics

🧮 在线计算器：Bolt Pre-selection Calculator — Fast sizing with the Kübler equation; supports a design mode and a check mode. Introduction: the rubber-band-and-sponge model To fully understand the physical logic behind the “bearing-pressure check”, we can picture the bolted-joint system as “a stretched rubber band (the bolt) clamping a sponge (the clamped part)”. The heart of this part is to reveal a key question: why, when a part’s surface is crushed just a little bit, does the whole bolted joint face the risk of complete failure? ...

🧮 在线计算器：Bolt Pre-selection Calculator — Fast sizing with the Kübler equation; supports a design mode and a check mode. The reduction factor $\kappa$ explained: the “invisible tax” of tightening a bolt 📎 Prerequisite reading: this article is a deeper supplement to Bolt Pre-selection (001) — From Load to Size , focusing on the physical nature and derivation of the $\kappa$ parameter in the denominator of the Kübler equation. In the design and installation of a bolted joint, the reduction factor $\kappa$ (Reduktionsfaktor) is a very central parameter. It answers a key question: while the bolt is being tightened, how much strength is still “available” for axial load carrying? Below we break down its definition, derivation and formula, based on the public technical standard VDI 2230. ...