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Figure 18. Factor of safety for tulip with nodal displacements. 3.7 Structural Analysis with Elastic Support

Figure 18 Factor of safety for tulip with nodal displacements. 3.7 Structural Analysis with Elastic Support

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NED UNIVERSITY JOURNAL OF RESEARCH - STRUCTURAL MECHANICS, VOL XVIII, NO. 3, 2021 from the global model. Structural analysis of wing tulip isolated from the wing under applied loads is carried out in this paper to determine the maximum stress on the tulip. Effects of various boundary conditions on the maximum stress have been examined. A scheme of analysis has been identified to include the stiffness of the attached structure through application of appropriate boundary condition. This paper identifies the most appropriate boundary condition for the analysis of structural member isolated from the global model. identifies the most appropriate boundary condition for the analysis of structural member isolated
NED UNIVERSITY JOURNAL OF RESEARCH - STRUCTURAL MECHANICS, VOL XVIII, NO. 3, 2021 from the global model. Structural analysis of wing tulip isolated from the wing under applied loads is carried out in this paper to determine the maximum stress on the tulip. Effects of various boundary conditions on the maximum stress have been examined. A scheme of analysis has been identified to include the stiffness of the attached structure through application of appropriate boundary condition. This paper identifies the most appropriate boundary condition for the analysis of structural member isolated from the global model. identifies the most appropriate boundary condition for the analysis of structural member isolated
Figure 2. Global model of oil rig. To model the joint in detail, improved representation with a local shell model is made which is shown in Figure 3. Rigid elements are used to connect the shell mesh and the beam mesh. The shell elements represent the correct load transfer path in the walls between the intersecting cylinders. Therefore, stress concentration between the connecting members can be predicted correctly. Note that the computing resource for the improvised model is still much less compared to a full-scale solid model.
Figure 2. Global model of oil rig. To model the joint in detail, improved representation with a local shell model is made which is shown in Figure 3. Rigid elements are used to connect the shell mesh and the beam mesh. The shell elements represent the correct load transfer path in the walls between the intersecting cylinders. Therefore, stress concentration between the connecting members can be predicted correctly. Note that the computing resource for the improvised model is still much less compared to a full-scale solid model.
Figure 3. Rigid elements for connection of local model to global model. NED UNIVERSITY JOURNAL OF RESEARCH - STRUCTURAL MECHANICS, VOL XVIII, NO. 3, 2021
Figure 3. Rigid elements for connection of local model to global model. NED UNIVERSITY JOURNAL OF RESEARCH - STRUCTURAL MECHANICS, VOL XVIII, NO. 3, 2021
NED UNIVERSITY JOURNAL OF RESEARCH - STRUCTURAL MECHANICS, VOL XVIII, NO. 3, 2021 Computer aided design (CAD) model of the wing tulip was developed in Ansys DesignModeler®. The following material properties of 30CrMnSiA alloy steel were used for the tulip: modulus of elasticity = 196 GPa (1934x10° ksi); yield strength (o,) = 835 MPa (839 ksi); and Poison ratio (1) = 0.3. Solid model of the wing tulip is shown in Figure 5.
NED UNIVERSITY JOURNAL OF RESEARCH - STRUCTURAL MECHANICS, VOL XVIII, NO. 3, 2021 Computer aided design (CAD) model of the wing tulip was developed in Ansys DesignModeler®. The following material properties of 30CrMnSiA alloy steel were used for the tulip: modulus of elasticity = 196 GPa (1934x10° ksi); yield strength (o,) = 835 MPa (839 ksi); and Poison ratio (1) = 0.3. Solid model of the wing tulip is shown in Figure 5.
Table 1. Design loads for wing tulip
Table 1. Design loads for wing tulip
3.2 Design Load Case Inflight load simulation within the carriage-envelop of the aircraft provides the design load case for the wing tulip. The design load case for the wing tulip occurs at +4.5g symmetric pullup manoeuvre at 0.8 Mach number. Lift force at the design load is 4.5 times the instantaneous weight of the aircraft. The design load for the wing tulip is applied in the form of force and moment vector. Table 1 provides the design loads for the wing tulip.
3.2 Design Load Case Inflight load simulation within the carriage-envelop of the aircraft provides the design load case for the wing tulip. The design load case for the wing tulip occurs at +4.5g symmetric pullup manoeuvre at 0.8 Mach number. Lift force at the design load is 4.5 times the instantaneous weight of the aircraft. The design load for the wing tulip is applied in the form of force and moment vector. Table 1 provides the design loads for the wing tulip.
Figure 8 presents the applied loads and fixed support boundary condition on the tulip. Figure 9 illustrates the deformation field of the tulip under the design loads. It can be observed from the comparison of Figures 8 and 9 that boundary condition is closely simulated in the analysis. No displacement was observed at the attachment bolt holes in this case. Maximum deformation of 0.37 mm (0.015 in.) was observed on the flange of the tulip. The equivalent von-Mises stress is shown in Figure 10. In addition, maximum stress 1253 MPa (182 ksi) was observed on the bolt hole. Based upon the yield criteria of material, factory of safety (FoS) is equal to 0.67, as illustrated in Figure 11. The aircraft has experimentally demonstrated to fly at design load case without failure. Consequently, it can be concluded that the fixed support boundary condition under predicts the strength of the tulip and is the most conservative in nature. Application of fixed support boundary condition erroneously recommends reduction in inertial and aerodynamic loads on the tulip due to low FoS. Primarily, loads can be reduced either by reducing the weight of the payload or limiting ‘g’ loads within the flight envelope. However, reduction in the payload weight and limitation on the flight envelope both affect the operational role of the fighter aircraft. NED UNIVERSITY JOURNAL OF RESEARCH - STRUCTURAL MECHANICS, VOL XVIII, NO. 3, 2021
Figure 8 presents the applied loads and fixed support boundary condition on the tulip. Figure 9 illustrates the deformation field of the tulip under the design loads. It can be observed from the comparison of Figures 8 and 9 that boundary condition is closely simulated in the analysis. No displacement was observed at the attachment bolt holes in this case. Maximum deformation of 0.37 mm (0.015 in.) was observed on the flange of the tulip. The equivalent von-Mises stress is shown in Figure 10. In addition, maximum stress 1253 MPa (182 ksi) was observed on the bolt hole. Based upon the yield criteria of material, factory of safety (FoS) is equal to 0.67, as illustrated in Figure 11. The aircraft has experimentally demonstrated to fly at design load case without failure. Consequently, it can be concluded that the fixed support boundary condition under predicts the strength of the tulip and is the most conservative in nature. Application of fixed support boundary condition erroneously recommends reduction in inertial and aerodynamic loads on the tulip due to low FoS. Primarily, loads can be reduced either by reducing the weight of the payload or limiting ‘g’ loads within the flight envelope. However, reduction in the payload weight and limitation on the flight envelope both affect the operational role of the fighter aircraft. NED UNIVERSITY JOURNAL OF RESEARCH - STRUCTURAL MECHANICS, VOL XVIII, NO. 3, 2021
Figure 8. Loads and fixed boundary condition on tulip.
Figure 8. Loads and fixed boundary condition on tulip.
Pee, Meee: Figure 10. Equivalent stress on tulip with fixed support. NED UNIVERSITY JOURNAL OF RESEARCH - STRUCTURAL MECHANICS, VOL XVIII, NO. 3, 2021
Pee, Meee: Figure 10. Equivalent stress on tulip with fixed support. NED UNIVERSITY JOURNAL OF RESEARCH - STRUCTURAL MECHANICS, VOL XVIII, NO. 3, 2021
NED UNIVERSITY JOURNAL OF RESEARCH - STRUCTURAL MECHANICS, VOL XVIII, NO. 3, 2021
NED UNIVERSITY JOURNAL OF RESEARCH - STRUCTURAL MECHANICS, VOL XVIII, NO. 3, 2021
Figure 13. F inite element model of wing with skin. Nodal displacement obtained from the solution of the wing model can be used as displacement boundary condition on the tulip instead of fixed support. Finite element analysis of the wing model was carried out under design load to generated deformation field of the wing. Figure 14 illustrates the deformation field of the wing under the design load. 3.6 Structural Analysis with Nodal Displacement
Figure 13. F inite element model of wing with skin. Nodal displacement obtained from the solution of the wing model can be used as displacement boundary condition on the tulip instead of fixed support. Finite element analysis of the wing model was carried out under design load to generated deformation field of the wing. Figure 14 illustrates the deformation field of the wing under the design load. 3.6 Structural Analysis with Nodal Displacement
NED UNIVERSITY JOURNAL OF RESEARCH - STRUCTURAL MECHANICS, VOL XVIII, NO. 3, 2021
NED UNIVERSITY JOURNAL OF RESEARCH - STRUCTURAL MECHANICS, VOL XVIII, NO. 3, 2021
Figure 15. Load and displacement boundary condition on tulip. tulip is 1.07 as illustrated in Figure 18. Nodal displacements at the bolt holes of the tulip were used as boundary condition. These nodal displacements were applied as fixed displacement in Ansys. Loads and boundary conditions for the tulip are shown in Figure 15. Maximum deformation of the tulip under the design load (Figure 16) is 0.32 mm (0.013 in.) on its flange. Equivalent stress on the tulip under the design load is presented in Figure 17. Maximum stress of 782 MPa (113 ksi) occurs at bolt holes of the tulip. FoS for the tulip is 1.07 as illustrated in Figure 18.
Figure 15. Load and displacement boundary condition on tulip. tulip is 1.07 as illustrated in Figure 18. Nodal displacements at the bolt holes of the tulip were used as boundary condition. These nodal displacements were applied as fixed displacement in Ansys. Loads and boundary conditions for the tulip are shown in Figure 15. Maximum deformation of the tulip under the design load (Figure 16) is 0.32 mm (0.013 in.) on its flange. Equivalent stress on the tulip under the design load is presented in Figure 17. Maximum stress of 782 MPa (113 ksi) occurs at bolt holes of the tulip. FoS for the tulip is 1.07 as illustrated in Figure 18.
Figure 17. Equivalent stress on tulip with nodal displacements. NED UNIVERSITY JOURNAL OF RESEARCH - STRUCTURAL MECHANICS, VOL XVIII, NO. 3, 2021
Figure 17. Equivalent stress on tulip with nodal displacements. NED UNIVERSITY JOURNAL OF RESEARCH - STRUCTURAL MECHANICS, VOL XVIII, NO. 3, 2021
Figure 19. Loads and elastic support on tulip.
Figure 19. Loads and elastic support on tulip.
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