Differential torque analysis

In some critical assemblies, such as the fitting of an internal combustion engine cylinder head, correct clamping load is vital. Either the traditional torque/tension method, or the more recently developed techniques of differential torque analysis must therefore be used. With torque/tension, the relationship must not be modified by the anaerobic materials used to lock the stud and nut. It has been shown that the relationship remains effectively unaltered if the fasteners are not degreased before assembly. For maximum precision, cleaned fasteners may be used in conjunction with special lubricating anaerobic versions. 

The early analysis of solids conveying in an extruder evolved through several simple models based on simple concepts such as the frictional forces between the polymer and the metal surfaces is credited to Decker [36] and Maillefer [37] and the concept of the differential torque at the screw and barrel surface was introduces by Simonds [38]. The rigor of the derivation was significantly improved by Darnell and Mol of DuPont and their analysis is most often cited as it gives a good description of the behavior observed. The model is based on the force and torque balance developed on the solid plug, which is assumed to completely fill the screw channel. The basic assumptions used for the derivation of the model are ... 

Other dimensional systems have been developed for special appHcations which can be found in the technical Hterature. In fact, to increase the power of dimensional analysis, it is advantageous to differentiate between the lengths in radial and tangential directions (13). In doing so, ambiguities for the concepts of energy and torque, as well as for normal stress and shear stress, are eliminated (see Ref. 13). 

ABSTRACT The paper presents an analysis of deviations in diameter D and pitch coefficient P/D and their impact on the determination of efficiency, torque, thrust and power calculated using the exact differential method. 

The dynamic moments are found by differentiating the kinetic energy equations by the Lagrangian operators. The torque at the pivot is found by equating the static forces and the dynamic moment. Analysis of free body diagram for each link yeilds the torque equations. 

ILs have been recently evaluated as non-volatile plasticizers and as external or internal lubricants in several polymers including PVC [3], PMMA [4] and polyamides [5]. In this article, an amorphous PL A (polylactide) polymer is blended with two phosphonium-based ILs at various ratios by melt-blending, solution casting and a microencapsulation technique in order to investigate polymer/IL miscibility and its role in the development of a modified polymer with novel rheological, mechanical and thermal characteristics. Results of thermogravimetric analysis, differential scanning calorimetry, capillary rheometry, batch mixer torque measurements and optical microscopy are discussed. 

---