Preload

🧮 在线计算器：VDI 2230 Bolted Joint Calculation — The full 14-step calculation chain (R0–R13), with six strength checks. Full worked example: tapped-thread joint (ESV) This article is a counterpart to the DSV example (article 8) . It highlights the differences unique to ESV: $w = 2$, $E_M = E_{BI}$, the cone-angle formula Eq. 42, and the R11 engagement-depth check. Engineering problem statement A bolt is screwed from the top into a cast-iron housing (grey cast iron GJL-250), fixing a steel cover plate. ...

🧮 在线计算器：VDI 2230 Bolted Joint Calculation — The full 14-step calculation chain (R0–R13), with six strength checks. Full worked example: through-bolt joint (DSV) This article ties all the theory of the previous 7 articles into one complete calculation chain. Using a concrete engineering case, we go through every step of R0–R13. Engineering problem statement A steel flange joint using a single bolt to fix a cover plate. The design requirements are: ...

🧮 在线计算器：VDI 2230 Bolted Joint Calculation — The full 14-step calculation chain (R0–R13), with six strength checks. Preload design: from functional requirement to assembly preload (R1–R6) The 14-step VDI 2230 calculation chain splits into a design part (R0–R6) and a verification part (R7–R13). This article explains the core steps of the design part. 1. R0 — preliminary diameter selection The task of R0 is to preliminarily fix the nominal diameter $d$ based on experience or a simplified method (such as the Kübler equation), and to check the interface limiting dimension (VDI 2230:2015, §4.2, Eq. R0/1, R0/2): ...

🧮 在线计算器：VDI 2230 Bolted Joint Calculation — The full 14-step calculation chain (R0–R13), with six strength checks. The “spring philosophy” of a bolted joint — the core physical model of VDI 2230 1. The spring model: the physical basis of VDI 2230 The starting point of all VDI 2230 calculations is to model the bolted joint as two sets of springs (VDI 2230:2015, §3.2, p.20): “In this model, the bolt and the clamped parts are considered as tension and compression springs with the elastic resiliences $\delta_S$ and $\delta_P$.” ...

🧮 在线计算器：VDI 2230 Bolted Joint Calculation — The full 14-step calculation chain (R0–R13), with six strength checks. 💡 Engineer, before blaming “poor bolt quality”, look at this real case — The connecting-rod bolts of a passenger-car engine failed catastrophically: the left bolt showed a typical one-sided bending fatigue fracture (a crescent-shaped fatigue region on the fracture surface), and the right bolt then broke suddenly from the force imbalance. Post-failure analysis found that the “culprit” was not the bolt material but insufficient preload. Because of assembly micro-embedding (Setzen), the preload dropped; under an eccentric service load, the connecting-rod interface opened slightly on one side, invisible to the eye (Aufklaffen), which caused a fatal alternating bending stress, finally initiating a fatigue crack at the shank root and a chain fracture. ...