Assessment of Real-World Bolted Joints by Combining FEA With VDI Guidelines

Real-world bolted connections are subjected to axial, bending and transverse working loads which are mostly difficult to ascertain purely by hand calculations and Free body diagrams (FBDs). VDI 2230 document which is largely followed across the industry for bolted joint assessments, assumes that this load data is readily available to the users. However, that is not always the case. Present work tries to address this aspect of bolted joint assessment by providing physics-based guidelines to ascertain these loads by using Finite Element Tools. Bolted joint phenomenon like Prying effect may be obvious in simple cases, however quantifying this effect in real life problems is quite challenging. Authors have suggested simple, but effective method, to quantify this effect by using Finite Element Analysis (FEA). Related to bending load on bolts, VDI explains that only a fraction of total bending moment observed by a joint is seen by the bolt, which is related to the relative bending resilience of members and bolts. VDI document assumes that the members have standard shapes and are simple prismatic discs. This is not true for most of the real-world bolted joints. Using FEA, bending loads are accurately deduced in this study. Similarly, the effect of load introduction planes, though captured in VDI, may be very challenging and subjective to apply on actual bolted joints. The use of FEA to accurately capture this effect is also explained. Finally, the paper also explains how to use this data as input into SR1 software which is an industry standard tool for bolted joint analysis based on VDI guidelines. The paper intends to enable the readers to make better and informed evaluations of their bolted joints by deploying techniques outlined in this body of work.