## 5 Guidelines  
The basic purpose of this exercise was to observe the limitations of SHSS methods and propose a guideline for the calculation of SHSS results that can be used by the design engineer for better evaluation of fatigue-related problems. Therefore, these methods were applied to the fatigue prone RD joint in the OSD specimen considering different element types and meshing techniques for the evaluation of SHSS at the deck and the rib-toe. A full-scale 3D OSD specimen was simulated and tested on an FEM based software Siemens NX.12.0 for the better understanding of stress behaviour at this critical joint. The optimized breakout modelling solution was adopted to increase the efficiency of the model and to reduce the cost of analysis. Four types of elements were used for the modelling with different mesh techniques and sizes, i.e., 8 node cubic linear hexahedral (CH8/8E) and 20 node parabolic hexahedral (CH20/20E) elements for 3D solid models, and 4 node cubic linear quadrangle (CQ4) and 8 node parabolic quadrangle (CQ8) elements for 3D-shell models. Moreover, the effect of the nodal averaging feature was studied on these SHSS evaluation methods. Two types of governing stresses were produced; essentially, bending in the deck-plate produced highly non-linear stress at the deck-toe, and the membrane effect in the rib-plate produced linear compressive stress at the rib-toe. From the application of four different SHSS evaluation methods on these two stress states, the following guidelines are proposed considering different parameters. These guidelines are summarized in Figure 10.  
* The IIW SSE (i.e., QSE, LSE 410, and LSE 515) methods showed consistency in the SHSS results. The QSE method gave better results as compared to LSE methods when stress was highly non-linear (deck-toe) due to its quadratic nature, which incorporated the part of the non-linear stress peak and gave a better representation of the actual stress scenario at the hot-spot. The LSE methods performed better where stress was linear (rib-toe), particularly, the LSE 515 method gave exceptionally converged SHSS results for both stress states. These methods exhibited lower and somewhat scattered SHSS results for solid elements (CH20/8 and CH20E/8E), especially in linear elements (CH8/CH8E), whereas shell elements (1/2-CQ8/4) showed higher and consistent SHSS results for both stress states. The solid parabolic single elements (CH20E) outperformed other meshing techniques in the QSE method but gave slightly lower results for solid parabolic elements (CH20). Moreover, for same simulated OSD model, the 1-CH20E element had three times fewer nodes as compared to 1-CH20 element, which saved computation time and analysis cost (Figure 10). Hence, it is better to use CH20E elements with the IIW QSE method for the evaluation of SHSS in the case of non-linear stress, and the LSE 515 method shall be preferred for nominal stress calculation with shell parabolic elements (1/2-CQ8), as shown in Figure 10.
* The Haibach method for SHSS evaluation is also based on surface stress calculation. Therefore, it had somewhat similar results as the IIW SSE methods, but values were somewhat scattered. The scatter in SHSS results was quite justified, as we relied on a stress value at a particular distance from the weld-toe (i.e., 2.5 mm). In this method, shell elements (1/2-CQ8/4) had lower results for non-linear stress state and higher results for linear stress state as compared to solid elements (CH20/8 and CH20E/8E). Similarly, in this method, the solid single parabolic element (CH20E) outperformed other meshing techniques, especially for non-linear stress; however, for nominal stress calculation, it is better to use shell parabolic elements (1/2-CQ8), as shown in Figure 10.
* The ASME through thickness stress linearization (TTSL) method performed better as compared to other SHSS evaluation methods.