WRC 344:1989

$23.40

Part 1: Three-Dimensional Finite Element Analysis of PVRC 45 Degree Lateral Model 4 (d/D = 0.5, D/T = 40) Under Out-Of-Plane Moment Loading on Branch Pipes; Part 2: Three-Dimensional Finite Element Analysis of 45 Degree Lateral Model 2 (d/D = 0.5, D/T = 10)

Published By	Publication Date	Number of Pages
WRC	1989	23

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Description

Part 1: Three Dimensional Finite Element Analysis Of PVRC 45 Degree Lateral Model 4 (d/D = 0.5, D/T = 40) Under Out-Of-Plane Moment Loading On Branch Pipes

This report presents the results of a three-dimensional finite element analysis of a 45 degree lateral (Model 4 of an earlier Phase I Program with geometric parameters d/D = 0.5 and D/T = 40, and a stress ratio s/S = 1.0).

A half symmetry model generated earlier under Phase I of the PVRC Long Range Program on Laterals was used in the present analysis. In the Phase I model, the finite element mesh consisted of 2208 eight node isoparametric solid elements. Except for the branch pipe, three or more layers of finite elements were used through the thickness of the entire model. Critical zones of the crotch regions were modeled using five elements through the thickness in the acute region and six elements in the obtuse region.

As a logical extension to Phase 1, an out-of-plane moment loading on the branch pipe was selected for the current evaluation.

The stress indices based on the extrapolated Gaussian point stress values on the inside and outside surfaces of the selected locations are presented and compared with the results of the in-plane moment loading.

Part 2: Three Dimensional Finite Element Analysis Of 45 Degree Lateral Model 2 (d/D = 0.5, D/T = 10) Under Out-Of-Plane Moment Loading On The Branch Pipe

This report presents the results of a three-dimensional finite element analysis of 45 degree lateral Model 2 with geometric parameters of d/D = 0.5 and D/T = 10, and stress ratio s/S = 1.0 subjected to an out-of-plane moment loading on the branch pipe.

A half-symmetry model generated earlier under Phase 1 of the PVRC Long Range Program on Laterals was regenerated for the present analysis. The finite element model consisted of 2600 eight-node isoparametric solid elements and 3693 nodal points. Out-of-plane moment loading was simulated through equivalent nodal forces applied at the branch end. One end of the run pipe was restrained completely in all, directions and antisymmetry displacement boundary conditions were applied on the symmetry plane.

A maximum stress index product (C₂K₂) of 1.12 was calculated at the branch pipe to nozzle juncture at T = 90° from the symmetry plane (transverse plane). This value is considerably less than 2.5 obtained earlier for Model 4. This comparison indicates that the diameter-to-thickness ratio of the run pipe has a significant influence on the stress intensification due to out-of-plane moment loading. Model 2 also appears to be much stiffer than Model 4 at the crotch region. This may be another reason for the reduced stress intensification in Model 2.

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