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Simulate to Innovate

Simulation

UTA (Umbilical Termination Assembly) &ROV (Remote Operated Vehicle) using RADIOSS

Atul Kumar Dixit Engineering Manager

Product Simulation Group (Analysis)

FMC Technologies India Pvt Ltd Hyderabad, AP, India

FMC Technologies, Inc. is a leading global provider of technology solutions for the energy industry. FMC Technologies is named by FORTUNE® Magazine as the World's Most Admired Oil and Gas Equipment, Service Company in 2012.Technologies designs, manufactures and services technologically sophisticated systems and products such as subsea production and processing systems, surface wellhead systems, high pressure fluid control equipment, measurement solutions, and marine loading systems for the oil and gasaccess formation fluids from well in the subsea, various equipment like 'X' trees, manifolds, ROVs are operated in the subsea. The control and communication of these equipments from thewhich is also placed in the subsea.UTA is a part of the subsea distribution system. It supplies hydraulic fluid, electricitychemicals and communication for the operation and maintenance of these equipUTA) etc are operated using hydraulic actuators. In case of failure of hydraulic actuators, valves are mechanically operatedusing Remote Operated Vehicle (ROV). During this phase, ROV might accidentally hit the

It is required to verify whether this impact can affect the functionality of the structure. For this reason, UTH needs to beverified for its structural integrity under the action of this impact energy and qualified as peSteel Structures).To verify the possible damage in UTH due tochosen.


Simulation of Impact between UTA (Umbilical Termination Assembly) &

Operated Vehicle) using RADIOSS / Explicit Solver

Narasimha Chopparapu Engineer



Pradeep Kumar MishraAssociate Engineer


FMC Technologies India Pvt LtdHyderabad, AP, India

Abstract FMC Technologies, Inc. is a leading global provider of technology solutions for the energy industry. FMC Technologies is

Magazine as the World's Most Admired Oil and Gas Equipment, Service Company in 2012.actures and services technologically sophisticated systems and products such as subsea

production and processing systems, surface wellhead systems, high pressure fluid control equipment, measurement solutions, and marine loading systems for the oil and gas industry. In order to carry out drilling operations in subsea and to access formation fluids from well in the subsea, various equipment like 'X' trees, manifolds, ROVs are operated in the subsea. The control and communication of these equipments from the top side is made through subsea distribution system which is also placed in the subsea.UTA is a part of the subsea distribution system. It supplies hydraulic fluid, electricitychemicals and communication for the operation and maintenance of these equipments.Valves of ‘X’ trees, UTH (a part of UTA) etc are operated using hydraulic actuators. In case of failure of hydraulic actuators, valves are mechanically operatedusing Remote Operated Vehicle (ROV). During this phase, ROV might accidentally hit the UTH with certain impact energy.

It is required to verify whether this impact can affect the functionality of the structure. For this reason, UTH needs to beverified for its structural integrity under the action of this impact energy and qualified as per NORSOK standard (Design of Steel Structures).To verify the possible damage in UTH due to the impact made by ROV, RADIOSS

Simulate to Innovate 1

UTA (Umbilical Termination Assembly) & / Explicit Solver

Pradeep Kumar Mishra Associate Engineer



FMC Technologies, Inc. is a leading global provider of technology solutions for the energy industry. FMC Technologies is Magazine as the World's Most Admired Oil and Gas Equipment, Service Company in 2012. FMC

actures and services technologically sophisticated systems and products such as subsea production and processing systems, surface wellhead systems, high pressure fluid control equipment, measurement

industry. In order to carry out drilling operations in subsea and to access formation fluids from well in the subsea, various equipment like 'X' trees, manifolds, ROVs are operated in the

top side is made through subsea distribution system which is also placed in the subsea.UTA is a part of the subsea distribution system. It supplies hydraulic fluid, electricity,

ments.Valves of ‘X’ trees, UTH (a part of UTA) etc are operated using hydraulic actuators. In case of failure of hydraulic actuators, valves are mechanically operated

UTH with certain impact energy.

It is required to verify whether this impact can affect the functionality of the structure. For this reason, UTH needs to be r NORSOK standard (Design of

the impact made by ROV, RADIOSS Explicit solver has been


Section

1.0 Introduction

2.0 Objective

3.0 Model Description

3.1 Geometry

3.2 Finite Element Model

3.3 Interfaces

3.4 Bolt Pretension

3.5 Materials ................................

3.6 Loading and boundary conditions

4.0 Design Criteria

5.0 Results Discussion

6.0 Solution Quality Check

7.0 Challenges

8.0 ACKNOWLEDGEMENTS

9.0 REFERENCES


Table of Contents Title

Introduction ................................................................

Objective ................................................................

Model Description ................................................................

Geometry ................................................................

Finite Element Model ................................................................

Interfaces ................................................................

Bolt Pretension ................................................................

......................................................................................

Loading and boundary conditions ................................

Design Criteria ................................................................

Discussion ................................................................

Solution Quality Check .............................................................

Challenges ................................................................

ACKNOWLEDGEMENTS ...........................................................

REFERENCES ................................................................


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Tables

Table 1: Material Data ................................


List of Tables

................................................................................................


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Figures

Figure 1: Typical Subsea Production Layout

Figure 2: Umbilical Termination Assembly

Figure 3: The UTH & the ROV

Figure 4: Geometry Description of the UTH structure

Figure 5: Finite Element Model of the UTH

Figure 6: Type 7 Frictional Sliding Interfaces

Figure 7: Zoom Views of Type 7 Interfaces

Figure 8: Locations of Spot Welds

Figure 9: Bolts in the Bolted Flange Interface

Figure 10: Stress Strain Curves for the Components of the UTH Box

Figure 11: Loading and Boundary Conditions

Figure 12: Boundary Condition

Figure 13: Impactor (ROV) Velocity

Figure 14: Displacement Plot of the UTH structure

Figure 15: Clearance between the UTH Box Pad Eye & the Support Ears

Figure 16: von Mises Plastic Strain Plot in the UTH structure

Figure 17: von Mises Plastic

Figure 18: von Mises Stress Plot in the UTH structure

Figure 19: von Mises Stress Plot in the Support Ears

Figure 20: von Mises Stress Plot in the Bolts

Figure 21: Energy Variation Plots w.r.t Time

Figure 22: Energy Error in the Model without Friction


List of Figures

Figure 1: Typical Subsea Production Layout ................................................................

gure 2: Umbilical Termination Assembly ................................................................

Figure 3: The UTH & the ROV ................................................................

Figure 4: Geometry Description of the UTH structure ................................

Figure 5: Finite Element Model of the UTH ................................................................

Figure 6: Type 7 Frictional Sliding Interfaces ................................................................

Figure 7: Zoom Views of Type 7 Interfaces ................................................................

Figure 8: Locations of Spot Welds ................................................................

Figure 9: Bolts in the Bolted Flange Interface ................................................................

Figure 10: Stress Strain Curves for the Components of the UTH Box .............................

Figure 11: Loading and Boundary Conditions ................................................................

Figure 12: Boundary Condition ................................................................

Figure 13: Impactor (ROV) Velocity ................................................................

Figure 14: Displacement Plot of the UTH structure .........................................................


Figure 16: von Mises Plastic Strain Plot in the UTH structure ................................

Figure 17: von Mises Plastic Strain Plot in the Support Ears ................................

Figure 18: von Mises Stress Plot in the UTH structure ................................

Figure 19: von Mises Stress Plot in the Support Ears ................................

Figure 20: von Mises Stress Plot in the Bolts ................................................................

Figure 21: Energy Variation Plots w.r.t Time ................................................................

Figure 22: Energy Error in the Model without Friction ................................


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Figure 15: Clearance between the UTH Box Pad Eye & the Support Ears...................... 17

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The following abbreviations are used throughout this document.

Abbreviation Description

c.o.f Coefficient of FrictionDOF DegreeFEA Finite Element AnalysisUTH Umbilical Termination HeadUTA Umbilical Termination ‘X’ Trees Christmas Treesksi Kilo pounds per square inchSDU Subsea Distribution UnitEDU Electrical Distribution Unitw.r.t with respect toNA Not ApplicableUTS Ultimate Tensile Strength


Abbreviations

The following abbreviations are used throughout this document.

Description

Coefficient of Friction Degrees of Freedom Finite Element Analysis Umbilical Termination Head Umbilical Termination Assembly Christmas Trees Kilo pounds per square inch Subsea Distribution Unit Electrical Distribution Unit with respect to Not Applicable Ultimate Tensile Strength



1.0 Introduction

In order to carry out drilling operations in subsea and to access formation fluids from well in the

subsea, various equipment like 'X' trees, manifolds, ROVs are operated in the subsea. Figure 1

shows typical subsea production layout.

Figure

The control and communication of these equipments from the top side is made through subsea distribution system which is also placed in the subsea. UTA is a part of the subsea distribution system which is shown in the figure 1. It supplies hydraulic fluid, electricity, chemicals and communication for the operation and maintenance of these equipments

Figure 2 shows the Umbilical Terminal Assembly (UTA). Umbilical Termination Head (UTH), Subsea Distribution Unit (SDU) and Electrical Distribution Unit (EDU) are the components of UTA.


carry out drilling operations in subsea and to access formation fluids from well in the


shows typical subsea production layout.

Figure 1: Typical Subsea Production Layout

The control and communication of these equipments from the top side is made through subsea distribution system which is also placed in the subsea. UTA is a part of the subsea distribution

figure 1. It supplies hydraulic fluid, electricity, chemicals and communication for the operation and maintenance of these equipments.

Figure 2 shows the Umbilical Terminal Assembly (UTA). Umbilical Termination Head (UTH), Subsea and Electrical Distribution Unit (EDU) are the components of UTA.


carry out drilling operations in subsea and to access formation fluids from well in the


The control and communication of these equipments from the top side is made through subsea distribution system which is also placed in the subsea. UTA is a part of the subsea distribution

figure 1. It supplies hydraulic fluid, electricity, chemicals and

Figure 2 shows the Umbilical Terminal Assembly (UTA). Umbilical Termination Head (UTH), Subsea and Electrical Distribution Unit (EDU) are the components of UTA.


Figure 2:

Valves of the ‘X’ trees, UTH etc are operated using hydraulic actuators. In case of failure of hydraulic actuators, valves are mechanically operatphase, ROV might accidentally hit the UTH with certain impact energy.

Figure 3 shows the UTH and the ROV.


Figure 2: Umbilical Termination Assembly

‘X’ trees, UTH etc are operated using hydraulic actuators. In case of failure of hydraulic actuators, valves are mechanically operated using Remote Operated Vehicle (ROV). During this phase, ROV might accidentally hit the UTH with certain impact energy.

Figure 3 shows the UTH and the ROV.


‘X’ trees, UTH etc are operated using hydraulic actuators. In case of failure of hydraulic ed using Remote Operated Vehicle (ROV). During this


It is required to verify whether this impact can affect the reason, UTH needs to be verified for its structural integrity under the action of this impact energy and needs to be qualified as per NORSOK standard (Design of Steel Structures).

To verify possible damage in the UTH structure due tosolver has been chosen to perform finite element analysis.

2.0 Objective

The objective is to simulate the impact made by Remote Operated Vehicle (ROV) on Umbilical Termination Head (UTH) and veri

Structural integrity of the UTH structure is verified by comparing the von Mises plastic strain observed in the structure with the allowable limit specified by NORSOK (Design of Steel Structures).

As per NORSOK, von Mises plastic strain in the structure should not exceed the minimum elongation limit of the structure’s material which is 18

3.0 Model Description

3.1 Geometry

Figure 4 shows the geometry of the Umbilical Termination Head (UTH).

The cross sectional area of the ROV tool with which it impacts the UTH is known. Hence the ROV is modeled as a simple geometry with the known crossof the impactor is adjusted to meet the ROV weight (6600 lbf)


Figure 3: The UTH & the ROV

It is required to verify whether this impact can affect the functionality of the UTH structure. For this reason, UTH needs to be verified for its structural integrity under the action of this impact energy and needs to be qualified as per NORSOK standard (Design of Steel Structures).

he UTH structure due to impact made by the ROV, RADIOSSsolver has been chosen to perform finite element analysis.

The objective is to simulate the impact made by Remote Operated Vehicle (ROV) on Umbilical Termination Head (UTH) and verify structural integrity of the UTH structure.


OK, von Mises plastic strain in the structure should not exceed the minimum elongation structure’s material which is 18 % in this case.

Model Description

Figure 4 shows the geometry of the Umbilical Termination Head (UTH).

sectional area of the ROV tool with which it impacts the UTH is known. Hence the ROV is modeled as a simple geometry with the known cross-section area and arbitrary depth and t

is adjusted to meet the ROV weight (6600 lbf).


functionality of the UTH structure. For this reason, UTH needs to be verified for its structural integrity under the action of this impact energy and

impact made by the ROV, RADIOSS Explicit

The objective is to simulate the impact made by Remote Operated Vehicle (ROV) on Umbilical


OK, von Mises plastic strain in the structure should not exceed the minimum elongation

sectional area of the ROV tool with which it impacts the UTH is known. Hence the ROV is a and arbitrary depth and the density


Figure 4

3.2 Finite Element Model

4 node shell 4N and 8 node solid HEX8 element types have been used for the finite element modeling of the structure. The average element size is 0.15” to 0.20”. The minimum elementto be 0.06 in.

Figure 5 shows the FEA model of the Umbilical Termination Head (UTH).


4: Geometry Description of the UTH structure

4 node shell 4N and 8 node solid HEX8 element types have been used for the finite element modeling of the structure. The average element size is 0.15” to 0.20”. The minimum element

Figure 5 shows the FEA model of the Umbilical Termination Head (UTH).


4 node shell 4N and 8 node solid HEX8 element types have been used for the finite element modeling of the structure. The average element size is 0.15” to 0.20”. The minimum element length was found


Figure

3.3 Interfaces

Frictional sliding interfaces in the model have been simulated using type 7 interface. the locations of type 7 interfaces.


Location 1 is the UTH pin (hinge) to pad eyes interface


Figure 5: Finite Element Model of the UTH

Frictional sliding interfaces in the model have been simulated using type 7 interface. the locations of type 7 interfaces.


Location 1 is the UTH pin (hinge) to pad eyes interface


Frictional sliding interfaces in the model have been simulated using type 7 interface. Figure 6 shows


Location 2 is the bolted flange interfaces

Location 3 is the impactor (ROV) and the UTH interface

Location 4 is the UTH and the support 2 interface


Co-efficient of friction = 0.08 has been used in the

Figure 7 shows the zoom views of type 7 in



Location 2 is the bolted flange interfaces

Location 3 is the impactor (ROV) and the UTH interface



efficient of friction = 0.08 has been used in the frictional sliding interfaces.

Figure 7 shows the zoom views of type 7 interfaces.




Weld joints are simulated using type 2 contact interfaces and spot welds.

Figure 8 shows the locations of spot welds in green color.

3.4 Bolt Pretension

Bolts are pre tensioned to a value of 7440 lbf.

To simulate pretension in bolts, rigid elements with master node option were created at each end of the bolts (bolt heads) and master nodes of each bolt are connected by SPRING2N elements. /PROP/TYPE32 (SPR_PRE) spring property was used for ramped over the time. The distance of impactor from the impacting surface was adjusted such that the bolt pretension was completely applied before the impact.

Figure 9 shows the bolts in the bolted flange interface.



Weld joints are simulated using type 2 contact interfaces and spot welds.

Figure 8 shows the locations of spot welds in green color.

Figure 8: Locations of Spot Welds

Bolts are pre tensioned to a value of 7440 lbf.

To simulate pretension in bolts, rigid elements with master node option were created at each end of the bolts (bolt heads) and master nodes of each bolt are connected by SPRING2N elements.

_PRE) spring property was used for spring 2N element types. Pretension is ramped over the time. The distance of impactor from the impacting surface was adjusted such that the bolt pretension was completely applied before the impact.

bolts in the bolted flange interface.



To simulate pretension in bolts, rigid elements with master node option were created at each end of the bolts (bolt heads) and master nodes of each bolt are connected by SPRING2N elements.

2N element types. Pretension is ramped over the time. The distance of impactor from the impacting surface was adjusted such that


3.5 Materials

All components of UTH are modeled using Elastic Plastic, Multi linear, Isotropic strain hardening material curve generated as per ASME (Boiler and Pressur(PLAS_TAB). Figure 10 shows the stress strain curves for the components of the UTH. Also, Refer table 1 for the material data.


Impactor (ROV) was modeled using linear elastic material with 100 times higher young’s modulus compared to young’s modulus of the UTH. This is a conservative approach in the sense that, during impact, most of the impact energy is absorbed by the UTH in straining itself and not the

Properties

Young's Modulus

Poisson's Ratio

Yield Strength

UTS

Minimum Elongation Limit


All components of UTH are modeled using Elastic Plastic, Multi linear, Isotropic strain hardening material curve generated as per ASME (Boiler and Pressure Vessel Code) using /MAT/LAW36

Figure 10 shows the stress strain curves for the components of the UTH. Also, Refer


using linear elastic material with 100 times higher young’s modulus compared to young’s modulus of the UTH. This is a conservative approach in the sense that, during impact, most of the impact energy is absorbed by the UTH in straining itself and not the

Table 1: Material Data

UTH Box Material Pin Material Bolt Material

30e6 30 e6 30e6

0.3 0.3 0.3

50ksi 85ksi 105ksi

70ksi 130 ksi 125ksi

18 % 21 % 21 %


All components of UTH are modeled using Elastic Plastic, Multi linear, Isotropic strain hardening e Vessel Code) using /MAT/LAW36

Figure 10 shows the stress strain curves for the components of the UTH. Also, Refer


using linear elastic material with 100 times higher young’s modulus compared to young’s modulus of the UTH. This is a conservative approach in the sense that, during impact, most of the impact energy is absorbed by the UTH in straining itself and not the impactor.

Impactor

30e8

0.3

N.A

N.A

N.A


3.6 Loading and boundary conditions


The impactor was given initial velocity of 1.6ft/s, normal to the side plate. Refer figure 11

Standard earth gravity is applied over the entire structure. Even though, the structure is placed in the subsea, the effect of buoyancy is not considered. This is astandard earth gravity applied and ignoring the buoyancy, the normal force betwthe UTH box will be high. HenceUTH box during impact will be high compared to the actual conditions. Hence, the more impact energy shall be absorbed by the UTH


Loading and boundary conditions


The impactor was given initial velocity of 1.6ft/s, normal to the side plate. Refer figure 11

applied over the entire structure. Even though, the structure is placed in the subsea, the effect of buoyancy is not considered. This is a conservative approach because, with standard earth gravity applied and ignoring the buoyancy, the normal force between the supports and the UTH box will be high. Hence, the frictional resistance offered by the supports to the motion of the UTH box during impact will be high compared to the actual conditions. Hence, the more impact energy shall be absorbed by the UTH structure.


The impactor was given initial velocity of 1.6ft/s, normal to the side plate. Refer figure 11 to figure 13.

applied over the entire structure. Even though, the structure is placed in the conservative approach because, with

een the supports and the frictional resistance offered by the supports to the motion of the

UTH box during impact will be high compared to the actual conditions. Hence, the more impact


The base of the each support is fixed in all degrees of freedom (DOF). Refer figure 1

4.0 Design Criteria

As per the NORSOK standard, after impact, the von Mises exceed material minimum elongation limit. In UTH structure is 18 %.

Hence, in order the UTH structure to be qualified as per the NORSOK standard, the maximuMises plastic strain in the UTH structure should not exceed 18 %.


fixed in all degrees of freedom (DOF). Refer figure 1

Figure 12: Boundary Condition

Figure 13: Impactor (ROV) Velocity

As per the NORSOK standard, after impact, the von Mises plastic strain in the structure should not exceed material minimum elongation limit. In this case, the material minimum elongation limit of the

Hence, in order the UTH structure to be qualified as per the NORSOK standard, the maximuMises plastic strain in the UTH structure should not exceed 18 %.


fixed in all degrees of freedom (DOF). Refer figure 12 and figure 13.

plastic strain in the structure should not case, the material minimum elongation limit of the

Hence, in order the UTH structure to be qualified as per the NORSOK standard, the maximum von


5.0 Results Discussion

The results of the analysis showed that the design of the UTH structure is safe for impact load case.

Figure 14 shows the displacement plot of the structure. Itthe UTH structure, the UTH box starts rotating about the UTH pin (extreme right in the figure) and slides over the supports.


While the UTH box is sliding over thfriction (work done against friction). Hence minimum impact energy has been transferred to the UTH box. So, the maximum von Mises plastic strain observed in the UTH structure is very lesRefer figure 14.

The motion of UTH box is a combination of translational and rotational motion. Translation motion is described by the sliding of the UTH box over the supports. Rotation motion is described by the rotation of the UTH box about the UTH pin which acts as a hinge for the UTH box.

Translation displacement (4”) of the UTH box UTH pin has been seen because of the clearance maintained between the UTH box pad eye and the support ears at the UTH pin location which acts as a hinge. Refer figure 15. Frictional contact interface is defined between the support ears and the UTH box pin. Radial frictional is also defined between the pin and the UTH box pad eye, support ears. Refer figure 15. displacement (4”) in the UTH box work against the friction between the suppo


Results Discussion


Figure 14 shows the displacement plot of the structure. It explains that, as the impactor (ROV) hits the UTH structure, the UTH box starts rotating about the UTH pin (extreme right in the figure) and


While the UTH box is sliding over the supports, most of the impact energy is utilized in overcoming the friction (work done against friction). Hence minimum impact energy has been transferred to the UTH box. So, the maximum von Mises plastic strain observed in the UTH structure is very les

The motion of UTH box is a combination of translational and rotational motion. Translation motion is described by the sliding of the UTH box over the supports. Rotation motion is described by the

the UTH pin which acts as a hinge for the UTH box.

of the UTH box and rotation displacement of the UTH box because of the clearance maintained between the UTH box pad eye and the

support ears at the UTH pin location which acts as a hinge. Refer figure 15. Frictional contact interface is defined between the support ears and the UTH box pin. Radial frictional is also defined between the pin and the UTH box pad eye, support ears. Refer figure 15.

UTH box structure helped in dissipating most of the impact energy by doing work against the friction between the supports and the UTH box interface.



explains that, as the impactor (ROV) hits the UTH structure, the UTH box starts rotating about the UTH pin (extreme right in the figure) and

e supports, most of the impact energy is utilized in overcoming the friction (work done against friction). Hence minimum impact energy has been transferred to the UTH box. So, the maximum von Mises plastic strain observed in the UTH structure is very less (0.2 %).

The motion of UTH box is a combination of translational and rotational motion. Translation motion is described by the sliding of the UTH box over the supports. Rotation motion is described by the

the UTH pin which acts as a hinge for the UTH box. Refer figure 14.

of the UTH box about the because of the clearance maintained between the UTH box pad eye and the

support ears at the UTH pin location which acts as a hinge. Refer figure 15. Frictional contact interface is defined between the support ears and the UTH box pin. Radial frictional contact interface is also defined between the pin and the UTH box pad eye, support ears. Refer figure 15. This

structure helped in dissipating most of the impact energy by doing



The analysis has been run for 550 milli seconds until the UTH box has stopped displacing further. This implies that some of the kinetic energy of the work against the friction at the interface between supports and the UTH box. the kinetic energy has been utilized in producing the plastic strain in the UTH box.

Figure 16 and Figure 17 show the von Mises plastic strain plots in the UTH structure. The maximum von Mises plastic strain in the UTH structure is observed to be 0.2 % which is less than the allowable limit of 18 % strain at failure.

Figure 16: von Mises Plastic Str



550 milli seconds until the UTH box has stopped displacing further. This implies that some of the kinetic energy of the impactor (3148 in-lbf) has been dissipated in doing work against the friction at the interface between supports and the UTH box. Refer figure 14. the kinetic energy has been utilized in producing the plastic strain in the UTH box.

igure 17 show the von Mises plastic strain plots in the UTH structure. The maximum von Mises plastic strain in the UTH structure is observed to be 0.2 % which is less than the allowable

Figure 16: von Mises Plastic Strain Plot in the UTH structure



550 milli seconds until the UTH box has stopped displacing further. lbf) has been dissipated in doing

Refer figure 14. Rest of the kinetic energy has been utilized in producing the plastic strain in the UTH box.

igure 17 show the von Mises plastic strain plots in the UTH structure. The maximum von Mises plastic strain in the UTH structure is observed to be 0.2 % which is less than the allowable

ain Plot in the UTH structure


Figure 17: von Mises Plastic Strain Plot in the Support Ears

Figure 18 to Figure 20 show the von Mises stress plots in the UTH structure



Figure 17: von Mises Plastic Strain Plot in the Support Ears

Figure 18 to Figure 20 show the von Mises stress plots in the UTH structure



Figure 18 to Figure 20 show the von Mises stress plots in the UTH structure.


Figure 19: von Mises Stress Plot in the Support Ears


6.0 Solution Quality Check

The following conditions are to be satisfied as per the RADIOSSwhether our solution gave valid result or the correct result.

Mass error should be less than 3 % (0.03)

Energy error should be negative and can be up to

Hour glass energy should be less than 10 % of tot

Hour glass + contact energy < 15 % of total energy

7.0 Challenges

In this analysis, the following conditions given in the solution quality check are not met.

� Energy error should be negative and can be up to

� Hour glass + contact energy < 15 % of total energy

Even then, the analysis is considered to be correct. The reasons are explained below.

Figure 21 shows the variation of various energies w.r.t time


19: von Mises Stress Plot in the Support Ears


Solution Quality Check

be satisfied as per the RADIOSS User Manual in order to verify whether our solution gave valid result or the correct result.

Mass error should be less than 3 % (0.03)

Energy error should be negative and can be up to -15 % (-5 % to -15 %)

Hour glass energy should be less than 10 % of total energy



Energy error should be negative and can be up to -15 % (-5 % to -15 %)



Figure 21 shows the variation of various energies w.r.t time.


User Manual in order to verify


15 %)




Energy error is calculated using the following expression,

The above equation can be re written as,

Referring to figure 21, it can be observed that the final kinetic energy in the sSome of the initial energy of the impactor is utilized

Most of the initial energy of the impactor friction in the contact interface between the supports and the UTH box. This frictional work done in the contact interface between the supports and the UTH box is accounted in the contact energy but not accounted in the energy error contact energy is observed in the solution which is reasonable.

In order to cross check that whether with removing friction (co-efficient of friction = 0.08observed in the solution is very less for



error is calculated using the following expression,

The above equation can be re written as,

Referring to figure 21, it can be observed that the final kinetic energy in the system is almost zero. of the impactor is utilized in permanently deforming the UTH structure.

t of the initial energy of the impactor has been dissipated in the form of work done against the friction in the contact interface between the supports and the UTH box. This frictional work done in

t interface between the supports and the UTH box is accounted in the contact energy but error equation shown above. Hence, the high energy error and high

contact energy is observed in the solution which is reasonable.

to cross check that whether the above explained reason is correct, the solution has been run efficient of friction = 0.08) at all interfaces. This time, the energy error

ed in the solution is very less for the same time point, as shown in the Figure 22.


ystem is almost zero.

in permanently deforming the UTH structure.

has been dissipated in the form of work done against the friction in the contact interface between the supports and the UTH box. This frictional work done in

t interface between the supports and the UTH box is accounted in the contact energy but . Hence, the high energy error and high

above explained reason is correct, the solution has been run the energy error

point, as shown in the Figure 22.


Figure 22:

8.0 ACKNOWLEDGEMENTS

The authors would like to thank Altair Engineering, India for providing technical support and bringing experts to FMC India office to build a strong

9.0 REFERENCES

[1] Altair Engineering, RADIOSS user manual

[2] Practical Finite Element Analysis, Nitin S. Gokhale, Sanjay S. Deshpande, Sanjeev V. Bedekar,Dr. Anand N. Thite

[3] NORSOK, Design of Steel Structures

[4] American Society of Mechanical Engineers


Figure 22: Energy Error in the Model without Friction

ACKNOWLEDGEMENTS

The authors would like to thank Altair Engineering, India for providing technical support and bringing experts to FMC India office to build a strong team in explicit simulation in Altair RADIOSS

RADIOSS user manual

Nitin S. Gokhale, Sanjay S. Deshpande, Sanjeev V. Bedekar,Dr. Anand N. Thite

Structures

[4] American Society of Mechanical Engineers (ASME)


The authors would like to thank Altair Engineering, India for providing technical support and bringing cit simulation in Altair RADIOSS.

Nitin S. Gokhale, Sanjay S. Deshpande, Sanjeev V. Bedekar,Dr. Anand N. Thite

simulation of impact between uta (umbilical termination ... · pdf fileuta (umbilical...

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