Flexcom represents an industry-standard finite element simulation framework designed specifically for complex marine and offshore engineering applications. visit the website Originally developed by MCS Kenny and continuously advanced under Wood’s digital solutions portfolio, Flexcom enables structural engineers, subsea designers, and naval architects to model non-linear dynamic behaviors of slender structural systems exposed to harsh hydro-environmental conditions.
As global offshore developments transition deeper into harsh environments and pivot toward offshore floating wind, wave energy, and complex subsea tie-backs, traditional linear dynamic structural models fail to capture extreme non-linear phenomena. Flexcom bridges this gap by offering robust 3D implicit time-domain and frequency-domain non-linear formulations engineered for flexible risers, steel catenary risers (SCRs), floating wind platforms, dynamic power cables, and subsea pipelines.
Technical Foundations & Core Formulation
At its numerical core, Flexcom is built around a specialized finite element solver capable of handling geometric and material non-linearities, dynamic wave-structure interaction, contact mechanics, and hydro-elastic coupling.
Specialized Beam-Column & Hybrid Formulations
Traditional three-dimensional beam elements struggle when applied to structures that combine high axial forces with low bending stiffness—such as dynamic electrical cables or long mooring lines. Standard formulations often encounter numerical stiffness ill-conditioning.
- 14-DOF Hybrid Finite Element: Flexcom solves this ill-conditioning by utilizing a hybrid formulation that incorporates axial force and internal torque directly as primary degrees of freedom rather than deriving them strictly from kinematic displacements. This structural element features 12 standard nodal spatial displacements and rotations supplemented by independent force variables enforced via Lagrangian constraint methods.
- Convected Coordinate Frame: To model large 3D non-linear displacements and rigid-body rotations under severe sea states, Flexcom attaches local co-rotational axis frames to individual elements. Internal virtual work equations operate within this moving frame, resolving non-linear strain-displacement relationships without numerical instabilities.
- Consistent Mass Matrix: Unlike simplified lumped-mass approaches, Flexcom generates a fully populated consistent mass matrix incorporating off-diagonal terms. This formulation accurately captures cross-coupled degrees of freedom, higher-order rotational inertia effects, and modal response characteristics under irregular wave excitation.
- Truss Element Option: Designed specifically for ultra-low bending stiffness components (such as heavy mooring chain segments), the integrated 3D truss element optimizes computational efficiency while retaining dynamic accuracy.
Core Engineering Modules and Functional Applications
Flexcom offers a modular suite catering to specific engineering disciplines within subsea, marine, and offshore renewable sectors.
+-----------------------------------+
| Flexcom Core FE Solver |
+-----------------------------------+
|
+-----------------------+-----------+-----------+-----------------------+
| | | |
+---------------+ +---------------+ +---------------+ +---------------+
| Subsea & | | Floating | | Subsea | | Offshore |
| Risers | | Offshore Wind | | Pipelines | | Mooring |
+---------------+ +---------------+ +---------------+ +---------------+
| • Flexible | | • Fully- | | • S-Lay / | | • Catenary |
| Risers | | Coupled | | J-Lay | | Systems |
| • Steel | | Aero-Hydro | | • On-bottom | | • Taut-leg |
| Catenary | | • Dynamic | | Stability | | Synthetic |
| • Drilling | | Power | | • Span | | • Turret |
| Systems | | Cables | | Analysis | | Coupling |
+---------------+ +---------------+ +---------------+ +---------------+
1. Riser Engineering and Analysis
Flexcom serves as a primary tool for designing flexible pipes, steel catenary risers (SCRs), hybrid riser towers, and top-tensioned risers (TTRs).
- Bending Hysteresis: The software incorporates advanced material constitutive models accounting for inter-layer friction slip within unbonded flexible pipe cross-sections. This friction mechanism generates bending hysteresis curves, accurately capturing structural damping during dynamic bending cycles. Wikipedia
- Seabed Interaction Models: Riser touchdown zone mechanics dictate dynamic fatigue life. Flexcom includes advanced non-linear seabed contact mechanics, including non-linear soil spring responses, trenching phenomena, suction resistance, and lateral friction degradation.
2. Floating Offshore Wind Energy (FOWT)
With the rapid expansion of offshore renewables, Flexcom has evolved into a fully coupled aero-hydro-servo-elastic simulation platform.
- Aerodynamic Coupling: Flexcom integrates with aerodynamic solvers (such as OpenFAST and NREL aero-modules), facilitating fully coupled dynamic analysis. The software simultaneously resolves aerodynamic wind loads on turbine blades, hydrodynamic wave-current loads on floating hulls (semi-submersibles, SPARs, TLPs), and dynamic stresses across inter-array/export cables and mooring lines.
- Dynamic Power Cables: Dynamic electrical cables experience complex tension-compression-bending combinations near the floating platform and cable protection systems (CPS). Flexcom evaluates minimum bending radii (MBR) and cumulative fatigue damages driven by platform wave motions.
3. Pipeline Installation & On-Bottom Integrity
Subsea pipelaying operations present high structural risks due to extreme tension and bending over stinger ramps and down touchdown zones.
- Pipelay Simulation: The solver supports static and dynamic pipelay modeling (S-Lay, J-Lay, and Reel-Lay procedures). It models tensioner settings, stinger roller contact points, barge motions, and pipe geometry.
- Free Span & Slugging Analysis: Flexcom calculates free-span vortex-induced vibration (VIV) fatigue hazards and dynamic internal multiphase flow instabilities (such as severe slugging). The internal fluid flow module couples spatial fluid mass changes with overall dynamic structural response.
4. Mooring System Design
Flexcom evaluates complex positioning systems for floating production storage and offloading units (FPSOs), semi-submersibles, and tension leg platforms (TLPs).
- Integrates catenary chain systems, steel wire ropes, and synthetic lines (polyester, HMPE).
- Captures non-linear stretch behavior, visit this site viscoelastic creep response, bottom contact friction, and line snap-load impacts.
Architectural Comparison: Hydrodynamic FEA Frameworks
To evaluate Flexcom’s technical positioning, it helps to compare it against other industry-standard software packages used for subsea and marine dynamics:
| Technical Feature / Capability | Flexcom | OrcaFlex | Abaqus / ANSYS (Explicit/Implicit) |
|---|---|---|---|
| Primary Focus | Slender offshore structures & riser dynamics | General marine hydrodynamics & slender structures | General structural & solid mechanics FEA |
| Element Formulation | 14-DOF Hybrid Beam-Column & Truss | Lumped-mass discrete line segments & Line elements | Solid, shell, 3D Timoshenko/Euler beam elements |
| Core Time Integration | Implicit Time-Domain (Hybrid solver) | Explicit & Implicit Time-Domain | Implicit/Explicit solvers |
| Flexible Pipe Hysteresis | Built-in inter-layer slip constitutive law | Hysteretic bending formulation | Requires custom UMAT/VUMAT user subroutines |
| Coupled Offshore Wind | Aero-hydro-servo-elastic (OpenFAST API integration) | Fully integrated aero-hydro-elastic | Custom co-simulation frameworks required |
| Setup & Run Speed | High efficiency for specialized slender lines | Extremely fast explicit solving for complex line networks | High computational expense for long dynamic runs |
Computational Methodology & Numerical Workflow
Executing robust structural assessments in Flexcom follows a structured engineering workflow:
[Preprocessing & Geometry Setup]
│ • Define line properties (OD, ID, E-Modulus, Mass, Drag/Inertia Coefficients)
│ • Generate FE discretisation & nodes
▼
[Environmental Conditions Setup]
│ • Regular/Irregular waves (JONSWAP, Pierson-Moskowitz spectra)
│ • 3D current profiles (shear flow) & aerodynamic wind fields
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[Static Equilibrium Solution]
│ • Nonlinear static solution (catenary geometry, pre-tension balancing)
│ • Seabed profile mapping and initial contact setup
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[Dynamic Solver Mode Selection]
├───> Frequency Domain Analysis (Fast linearised screening & fatigue iterations)
└───> Time Domain Analysis (Nonlinear 3D implicit time-integration)
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[Post-Processing & Code Checking]
│ • Tension, Bending Moment, Curvature & Stress time-histories
│ • Rainflow counting fatigue assessment (SN curves, miner damage summation)
│ • Design Code Validation (API RP 17B/17J, DNV-ST-F101, DNV-ST-0119)
- Pre-Processing & Discretization: The system geometry is established using a node-and-element mesh network. Material properties—such as mass per unit length, axial stiffness (EA), bending stiffness (EI), torsional stiffness (GJ), and hydrodynamic drag/inertia coefficients (Cd,Cm)—are applied per segment.
- Static Equilibrium Analysis: Flexcom solves the non-linear static configuration under self-weight, buoyancy, initial vessel offsets, and mean current drag forces. This establishes the non-linear stiffness matrix baseline.
- Dynamic Solution Execution:
- Frequency-Domain Mode: Linearizes non-linear wave drag and vessel transfer functions (RAOs) to provide rapid dynamic screening, spectral fatigue estimates, and preliminary line layout sizing.
- Time-Domain Mode: Integrates full non-linear differential equations of motion step-by-step through implicit integration schemes. It evaluates real-time sea states, extreme wave crests, dynamic contact events, snap loads, and vessel motion time histories.
- Post-Processing & Regulatory Compliance Verification: Results are processed into time-history traces, rainflow fatigue spectrums, and envelope plots. Flexcom features built-in post-processing macros that automate design check compliance against major offshore standards:
- API RP 17B / 17J: Flexible Pipe Systems Design & Operation Standards.
- DNV-ST-F101: Submarine Pipeline Systems.
- DNV-ST-0119 / DNV-RP-F108: Floating Wind Turbine Structures & Mooring Systems.
Strategic Industry Value & Future Evolution
As global energy demands mandate deepwater development and expanded offshore wind fields, software like Flexcom remains central to reducing engineering risks. The ability to accurately predict structural fatigue, dynamic line-to-line contact, seabed degradation, and extreme load responses allows operators to optimize material selection, minimize steel weight, prevent catastrophic subsea failures, and reduce overall capital expenditure (CAPEX).
Driven by digital transformation, Flexcom continues to evolve through virtual reality visualization interfaces, cloud-based parallel processing automation, and direct integration with real-time structural health monitoring (SHM) digital twins deployed on operational offshore assets.
Learn more about the modeling and structural response of deepwater risers in this Flexible Riser System simulation guide. This video illustrates a multi-line flexible riser system model passing over a mid-water arch, my blog offering visual context for the complex dynamic hydro-elastic interactions solved by Flexcom.