View
238
Download
2
Tags:
Embed Size (px)
DESCRIPTION
Análisis de Elementos finitos
Citation preview
ANSYS 14.5
Melter, S.A. DE C.V. {Calle “C” #511, Apodaca, N.L.; México} Customer: ECM TECHNOLOGIES, Winsconsin, USA MC-OT-973-01, Rev. 0 Item:RAP 7.8M3
1
FATIGUE & FEA ANALYSIS
“HP TANK 7.8 m3”
(MDI-973-1-1)
METHODOLOGY: FINITE ELEMENT ANALYSIS (FEA)
INDEX:
1. OBJECTIVE
2. DESIGN DATA
3. DEVELOPMENT
4. RESULTS
5. CONCLUSION
ANSYS 14.5
Melter, S.A. DE C.V. {Calle “C” #511, Apodaca, N.L.; México} Customer: ECM TECHNOLOGIES, Winsconsin, USA MC-OT-973-01, Rev. 0 Item:RAP 7.8M3
2
FINITE ELEMENT ANALYSIS (FEA) FATIGUE
“HP TANK 7.8 M3”
1.- OBJECTIVE
Performing Finite Element Analysis (FEA), to determinate the Fatigue acting stresses in shell, heads and
nozzle sections of pressure vessel named “HP TANK 7.8 M3”. The model will show the strains and stresses
result of the fatigue, the stress concentration zone and global performance. Besides, the peak zone and
global performance.
2.- DESIGN DATA
Design data of baseline for this study were taken from drawing MDI-973-1-1 and 3155 Specification HP Tank.
Equipment location = Wisconsin, USA Equipment size = 60” O.D. X 202” OAL Design pressure = 460 Psig /FV
Design temperature = 450 °F Operation pressure = 29 bars g ( 420.6 psi) (1) Operation temperature = AMB Material of Shell/heads/cones = SA-516-70 Material of flanges and forges = SA-105 Material of neck nozzles = SA-106 B Allowance stress Shell/heads/cones = 1490.5 kg/cm2 Yield stress Shell and flangesbridas = 2672 kg/cm2 (38000 psi ) AT Young´s module = 18.983x 105 kg/cm2 Poisson’s module = 0.3. Material’s density = 7850 kg/m3
(1) The equipment has a cyclical pressure. A pressure cycle corresponds to one depressurization (from 29 bars g to 20 bars g in 5 seconds) + one pressurization (from 20 bars g to 29 bars g in 8 minutes). The total cycle to be taken in account for fatigue sizing: 225,000 cycles. The Finite Element Analysis (FEA) and Fatigue Assessment will be done for the condition requested.
ANSYS 14.5
Melter, S.A. DE C.V. {Calle “C” #511, Apodaca, N.L.; México} Customer: ECM TECHNOLOGIES, Winsconsin, USA MC-OT-973-01, Rev. 0 Item:RAP 7.8M3
3
3. DEVELOPMENT
Methodology used for developing this study is based on mathematical modeling procedure, of structural
analysis called Finite Element Analysis (FEA). This procedure allows through different models, to evaluate
comprehensively mechanical performance of equipment elements (shell, heads, etc.) and Fatigue. Modeling
and execution analysis are accomplished in an automated way using one of the most important and
recognized analysis software ANSYS release 14.5. Overall model is shown in the following figures:
Fig. 1 Equipment FEA Model
ANSYS 14.5
Melter, S.A. DE C.V. {Calle “C” #511, Apodaca, N.L.; México} Customer: ECM TECHNOLOGIES, Winsconsin, USA MC-OT-973-01, Rev. 0 Item:RAP 7.8M3
4
Fig. 2 Equipment FEA Model
Fig. 3 Cross section
ANSYS 14.5
Melter, S.A. DE C.V. {Calle “C” #511, Apodaca, N.L.; México} Customer: ECM TECHNOLOGIES, Winsconsin, USA MC-OT-973-01, Rev. 0 Item:RAP 7.8M3
5
Finite Elements Models Finite Elements section
Boundary conditions. embedded at base plate
and legs.
Internal pressure = 460.0 psi
Range for fatigue 130.5 psi
Fig. 4 Finite Elements Model and Boundary Conditions
ANSYS 14.5
Melter, S.A. DE C.V. {Calle “C” #511, Apodaca, N.L.; México} Customer: ECM TECHNOLOGIES, Winsconsin, USA MC-OT-973-01, Rev. 0 Item:RAP 7.8M3
6
3.1 Analysis basis
a).- Criteria basis and mathematical formulation used on the model, below.
In the mathematical model suggested, the following elements were used: “Solid 185”, 8-node structural solid, each node with 3 degrees of freedom per node, and stiffness changes when big deformations and rigidity occur (non-lineal analysis).
Von Mises’ failure criterion was used for getting the acting stresses. Being the most recommendable criteria for cylinder evaluation, it is obtain below:
2ar
2
rt
2
ta2e2
Where:
a= Axial stress.
t = Tangential stress
r = Radial stress.
e = Equivalent stress
b).- Assesssment fatigue was executed applying paragraph 5.5.3 ASME Code Section VIII Division 2. “Fatigue Assesment – Elastic stress and Equivalent Stresses””. Equivalent stres ranges equation:
Alternating stress equation
ANSYS 14.5
Melter, S.A. DE C.V. {Calle “C” #511, Apodaca, N.L.; México} Customer: ECM TECHNOLOGIES, Winsconsin, USA MC-OT-973-01, Rev. 0 Item:RAP 7.8M3
7
Number of cycles equation.
Number of cycles stress-curve
1.00
10.00
100.00
1.00E+03 1.00E+04 1.00E+05 1.00E+06 1.00E+07 1.00E+08 1.00E+09
Esfu
erz
o e
n K
si
Numero de ciclos
Curva S-N
ANSYS 14.5
Melter, S.A. DE C.V. {Calle “C” #511, Apodaca, N.L.; México} Customer: ECM TECHNOLOGIES, Winsconsin, USA MC-OT-973-01, Rev. 0 Item:RAP 7.8M3
8
4.- RESULTS
Finite Element Análysis gave the followign results: 4.1 Condition 1: Own weight and Internal pressure stresses
Figura 5 Maximum strain 0.58 mm (0.022908 in).
Fig. 6 Maximum Von Mises stress 1149.14 kg/cm2 (16344.6 psi)
ANSYS 14.5
Melter, S.A. DE C.V. {Calle “C” #511, Apodaca, N.L.; México} Customer: ECM TECHNOLOGIES, Winsconsin, USA MC-OT-973-01, Rev. 0 Item:RAP 7.8M3
9
Fig. 7 Maximum strain botton head section = 0.25 mm (0.009875 in).
Fig. 8 Maximum Von Mises stress botton head section = 449.91 bars (6523.74 psi)
ANSYS 14.5
Melter, S.A. DE C.V. {Calle “C” #511, Apodaca, N.L.; México} Customer: ECM TECHNOLOGIES, Winsconsin, USA MC-OT-973-01, Rev. 0 Item:RAP 7.8M3
10
Fig 9 Maximum strain in shell 0.34 mm (0.013239 in).
Fig 10 Von Mises stress in flange = 1127.21 bars (16344.6 psi)
ANSYS 14.5
Melter, S.A. DE C.V. {Calle “C” #511, Apodaca, N.L.; México} Customer: ECM TECHNOLOGIES, Winsconsin, USA MC-OT-973-01, Rev. 0 Item:RAP 7.8M3
11
Fig 11 Maximum strain in top head = 0.58 mm (0.022908 in)
Fig 12 Von Mises stress in top head = 549.67 bars (7970.18 psi)
ANSYS 14.5
Melter, S.A. DE C.V. {Calle “C” #511, Apodaca, N.L.; México} Customer: ECM TECHNOLOGIES, Winsconsin, USA MC-OT-973-01, Rev. 0 Item:RAP 7.8M3
12
Fig 13 Stress on nozzle section= 1128.19 bars (16358.8 psi)
Fig 14 Stress on top head = 549.67 bars (7970.18 psi)
ANSYS 14.5
Melter, S.A. DE C.V. {Calle “C” #511, Apodaca, N.L.; México} Customer: ECM TECHNOLOGIES, Winsconsin, USA MC-OT-973-01, Rev. 0 Item:RAP 7.8M3
13
Fig 15 Stress on section Shell/nozzle = 934.26 bars (13546.8 psi)
Fig 16 Stress on botton head section = 449.91 bars (6523.74 psi)
ANSYS 14.5
Melter, S.A. DE C.V. {Calle “C” #511, Apodaca, N.L.; México} Customer: ECM TECHNOLOGIES, Winsconsin, USA MC-OT-973-01, Rev. 0 Item:RAP 7.8M3
14
Section 5.5.3, ASME Code Section VIII Division 2
Values for Equivalent Primary Stress + Secundary
Element SCL Location SN,K (psi) SN,K (kpsi) Nozzle 1 Inside Nozzle 16358.8 16.3588
Top Head 2 Inside Top Head 7970.18 7.97018
Shell 3 Inside Shell & Nozzle 13546.8 13.5468
Bottom head 4 Inside Bottom Head 6523.74 6.52374
Values for SPS
Element S (kpsi) SY (kpsi) SPS (kpsi) Nozzle 19.5 28.7 58.5
Top Head 21.2 31.75 63.6
Shell 21.2 31.75 63.6
Bottom Head 21.2 31.75 63.6
Efective Alternating of Equivalent Stress Amplitude
Element Location K f= K e,k= Sp,k (kpsi) Salt,k(kpsi) Nozzle Inside Nozzle 1 1 16.36 8.1794
Top Head Inside Top Head 1 1 7.97 3.9851
Shell Inside Shell & Nozzle 1 1 13.55 6.7734
Bottom Head Inside Bottom Head 1 1 6.52 3.2619
Number of Allowance Cycles
Element Location E T (kpsi) E FC (kpsi) SALT,K (kpsi) x NK (CICLOS) Notes Nozzle Inside Nozzle 29000 28300 8.1794 10.2322 17068063254 Passed
Top Head Inside Top Head 29000 28300 3.98509 11.4907 3.09531E+11 Passed
Shell Inside Shell & Nozzle 29000 28300 6.7734 11.4666 2.92796E+11 Passed
Bottom Head Inside Bottom Head 29000 28300 3.26187 11.4907 3.09531E+11 Passed
Nozzle element has the minumum cycles allowance = 1.71 E+10
5.- CONCLUSIONS The number of allowance cycles (1.71 E+10) is higher than cycles (225,000) required, so, the equipment design is accepted for this cycle pressure loads.