Many factors need to be considered when making this determination. the surrounding joint contains material to at least three times the bolt diameter). This can range from a relatively simple axisymmetric linear elastic finite element model to a fully nonlinear three dimensional finite element model incorporating geometric nonlinearities and frictional contact. As such, the methods described in the previous section should be applicable to most bolted joints. Durbin, Morrow and Petti [6] examined boundary effects of bolted joints when the bolt head diameter (or washer) is 1.5 times larger than the bolt diameter and in the restricted db/l range of 0.167 to 1.786. For real loads, this is non-trivial and multiple methods have been recommended. A change in temperature can cause an increase or a decrease in the preload of the bolt. For hard steels (i.e., brittle) where the ultimate strength approaches the true fracture stress, the Morrow and Goodman lines are essentially the same. It is preferable to have the bolt break rather than strip out the threads if a joint is going to fail [12]. at n = 0.5) at the bounds. Usually subscripted. The Machinery's Handbook [12] has precomputed data for various sizes of bolts, threads and friction coefficients. where Le is computed in the previous section. It will be recommended that the FEA empirical models be used when they are applicable and to use Shigley's frustum approach for all other cases. In addition to the yield limit equations for dowel-type connections, application of spacing, end, and edge distance requirements for connections and provisions related to bolt design â¦ â¢The diameter of this unthreaded rod is the average of the ... Head Type of Bolts ... C indicates the proportion of external load P that the bolt will carry. Although not shown, this significant difference begins at roughly an l/db ratio of about 2.0. Just to remind you, weâll follow the ASME BPVC Section VIII Division 1 Appendix 2 ((ASME, âMandatory Appendix 2 Rules for Bolted â¦ This source of this page is Brown et al., "Guideline for Bolted Joint Design and Analysis: Version 1.0," Sandia Report SAND2008-0371, Sandia National Laboratories, 2008. As can be seen in Figure 9, the methods are very similar for "thick" clamped joints when there is a significant fraction of soft material (i.e. Again consider the case of 5/8" bolt with a bolt head diameter of 15/16" (1.5 times the bolt diameter) clamping two "plates". BS449: Part 2 Bolt Grade 6.8, Loading Capacities of Ordinary Bolts per. Fig.2: Anchor Bolt design â¦ By combining the torque-angle curves with a few simple calculations â¦ It is planned for follow on work to extend the work of Morrow [9] to cases of more than two materials and perhaps to expand the range of geometries that it is applicable to. floodproofing, and construction of a floodwall in a â¦ Effective Young's modulus for a clamped stack consisting of multiple materials. This was the original assumption made by Shigley in his first edition mechanical engineering design book [8] and is what is chosen by Bickford [4]. These include better guidelines for choosing a pre-computed nut factor or using a method to compute a more accurate nut factor, bending effects (both globally applied that result in axial loads on the bolt and local bending on the bolt due to geometric effects such as bolting a pipe flange that has a gap between materials), fatigue analysis, extending the DMP method [9] to more than two materials and how to include thermal effects with it, and guidelines on designing bolted joints to carry shear load (including frictional capacity, shear pins, shear load applied to the bolts, etc.). A linear analysis allows for accurate geometric representation and loading effects and limited contact effect can also be incorporated. The column listing units is intended to provide the user with guidance regarding units. ΔLconstrained is the extension that will result in load being generated in the joint. With these assumptions, the bending stiffness for each layer can be computed to be, The moment of inertia, I, for the ith layer can be computed as, Once again assuming each layer is represented by a spring in series, the bending stiffness of the clamped material can be computed as. These are of course the conservative assumptions. Bolt torque (Nm, lb f ft): 1213 Note that standard dry torques are normally calculated to produce a tensile stress - or axial force or clamp load - in the bolt that equals to 70% of minimum tensile strength or 75% of proof strength. The value of D used for a given layer must take into account the frustum of the previous layer and not just the bolt or washer diameter. We will only consider cases where there is significant clamped materials around the bolt (i.e. Bickford [5] suggests that in general the shear ultimate strength for steels is between 0.55 (for stainless steels and aluminum) to 0.60 (for carbon steels) times the tensile ultimate strength. A summary of analytic approaches to compute a nut factor are given in Appendix A. Using a non-linear finite element analysis can be very expensive and requires significant expertise. Any geometric or material effects that significantly violate this assumption make the approaches in this section invalid. The first primary source of bending loads is direct bending applied to the bolt during the preload phase due to geometric effects. // --> As expected, the Wileman [17] and Morrow [9] methods produce similar results since Morrow's fit is based on extensions to Wileman's work. National Aeronautics and Space Administration, "Space Shuttle: Criteria for Preloaded Bolts", NSTS 080307 Revision A, July 6, 1998. where X and Y are chosen dependent on how much conservatism is desired. These include Soderberg. The bolt meets the factor of safety for the combined load if the following inequality is met. The classic example would be a pipe with a bending load applied to it. It is planned to update this document in the future, and this is one area that needs additional work. document.write(''); This is not a mature area and further investigation is needed in the future. Excel App. A., J. J. Comer and J. L. Handrock. The type of connection designed has an influence on member design and so must be decided even prior to the design of the structural system and design of members. color: 333399; // -->, Bolt Threads, Grade, Bolt Strength, Excel Spreadsheet Calculator, Bolt Pattern Group Pullout Excel Spreadsheet Calculator, Engineering Fundamentals of Threaded Fastener Design and Analysis, Calculating Assembly Torque per ISO 68 & ISO 724, Bolt Elongation Equation and Calculator while under Axial Stress, Fastener / Thread Tensile Area of External Thread Formula, Fastener / Threaded Pitch Circle Diameter Formula and Calculation, Fastener / Threaded Shear Area Formula and Calculation, Minimum Thread Engagement Formula and Calculation ISO, BS EN 20898-2 Proof load values - Coarse thread, Minimum Length of Thread Engagement Formula and Calculations Per FED-STD-H28/2B, Shear Area Internal and External Thread Formula and Calculation Per FED-STD-H28/2B, ANSI, ISO Thread Designations and References, Strength Grade Designation System of Steel Bolts and Screws, Self Tapping Screw Pull-Out and Torque Calculator, Torque Table Standard Bolt Sizes SAE Grades 1 - 8, Torque Values Stainless Steel Bolt Table Chart, Bolt Preload Tension Equation and Calculator, Torque vs Tension Bolts Table Chart SAE J429 Bolts, Torque Wrench Adapter Reduced Arm Calculation, Torque Wrench Adapter Extended Calculation, Guide to Design Criteria for Bolted and Riveted Joints, Hydraulic & Pneumatic Torque Wrenches Application Review, Fastener Thermal Expansion / Contraction Application and Equation, Press Fit Engineering and Design Equations, Bolt or Pin In Single Shear Equation and Calculator, Bolt or Pin In Double Shear Equation and Calculator, Single-Riveted Lap-Joint Formulas for Stress and Strength Design Equations and Calculator, Double-Riveted Lap-Joint Formulas and Calculator for Stress and Strength Design, Single-Riveted Lap-Joint with Inside Cover Plate Formulas and Calculator for Stress and Strength Design, Double-Riveted Lap-Joint with Inside Cover Plate Formulas and Calculator, Loading Capacities of Ordinary Bolts per.