Service overview
Stress, vibration, fatigue, nonlinear and composite structural simulation and design optimisation. This service is part of that division and is scoped individually around what you need to learn, decide or publish.
Composite materials combine fibres and matrix to deliver stiffness and strength at low weight, with properties that depend on how the plies are oriented and stacked. That tailorability is their strength and the source of their complexity: a laminate is anisotropic, its behaviour changes with layup and its failure involves several distinct mechanisms, such as fibre breakage, matrix cracking and delamination.
Simulation of composites ranges from classical laminate theory, which gives quick estimates of stiffness and ply stresses, to detailed three-dimensional models with progressive damage. The appropriate level depends on the question and the available data. Material data for composites are also more variable and more expensive to obtain than for metals, so the simulation approach must be matched to what can be measured and validated.
If you plan to publish the outcome, see manuscript & publication support, for example computational & simulation manuscripts or original research article writing.
What this service covers
Problems this service can address
- Anisotropy and layup effects that isotropic assumptions miss
- Delamination and damage modes that are hard to predict
- Limited property data for the specific laminate
Methods and analytical approaches
- Classical laminate theory and layered shell or solid models
- Failure criteria and progressive damage
- Micromechanics and homogenisation
- Delamination and cohesive-zone concepts
Applications
- Aerospace and automotive composite parts
- Wind-blade and pressure-vessel studies
- Composite repair evaluation
Relevant engineering disciplines
Scope, inputs and deliverables
Scope of work
- Definition of the physics, geometry and quantities of interest
- Model set-up with verification and, where data allow, validation
- Parametric or sensitivity studies agreed at scoping
- Results and documentation suitable for reports or publication
- Feasibility check on: layup, fibre and matrix properties
Typical inputs required from you
- Layup, fibre and matrix properties
- Loading and boundary conditions
- Coupon or component test data
Deliverables
- Composite model documentation
- Ply-level stress and failure indices
- Calibration and uncertainty statement
Highly specialised requests are first checked for feasibility from this information. Please do not send confidential data through the public form; describe it first and agree secure transfer afterwards.
Project workflow and method
- 01Enquiry and requirement assessment
- 02Technical scoping and proposal
- 03Execution
- 04Quality review and delivery, with an agreed round of revisions
Read the full project workflow.
In depth: how the work is done
Laminate theory and layered models
Classical laminate theory computes the extensional, coupling and bending stiffness of a layup from ply properties and orientations and gives ply-level stresses and strains under in-plane and bending loads. It is the basis of preliminary design and the check on finite element models. Layered shell elements extend this to complex geometries; layered solid elements capture through-thickness effects at higher cost. Coordinate systems and ply orientation conventions are a frequent source of errors, so they are checked explicitly.
Failure criteria and progressive damage
Failure criteria such as maximum stress, maximum strain or interactive criteria predict first-ply failure; some separate fibre and matrix modes. Progressive damage models degrade stiffness as damage develops and can predict post-initiation behaviour and ultimate strength, but they introduce parameters that need calibration against tests. Mesh sensitivity is a known issue for softening materials, and regularisation techniques are used. We select the level of damage modelling according to the question and the data available.
Micromechanics and homogenisation
Micromechanical models relate the properties of the constituents and the fibre arrangement to ply-level properties. Analytical rules of mixtures give estimates; representative volume element simulations capture fibre distributions, voids and interface effects more completely. Homogenisation passes effective properties to the structural model. These approaches help when ply data are unavailable or when the effect of a constituent change needs exploring, with the caveat that fibre-matrix interface properties are difficult to measure.
Delamination and cohesive-zone modelling
Delamination, the separation of plies, is a critical failure mode under impact and out-of-plane loading. Cohesive-zone elements represent interlaminar fracture through a traction-separation law calibrated with mode I and mode II fracture toughness tests. Fine meshes are needed in the cohesive region to resolve the fracture process zone, and the interaction with in-plane damage is considered. Results are sensitive to the cohesive parameters, so sensitivity studies are recommended.
Validation and variability
Composite properties vary with manufacturing quality, fibre volume fraction and environmental conditions. Simulations should be validated at several levels, from coupon tests through sub-components, and the variability of inputs considered through scatter or sensitivity analysis. We state clearly which results are validated and which are predictions, and we avoid presenting a single deterministic strength as if it were the property of the material.
Quality control and good practice
Quality-control approach
- Verification: mesh, time-step and solver sensitivity are examined before results are reported.
- Validation: results are compared with measurements or reference solutions where these exist, and the absence of such data is stated.
- Boundary conditions and material or fluid properties are recorded with their sources.
- Sensitivity to the least certain inputs is shown or explained.
Common pitfalls this service helps avoid
- Wrong ply orientation conventions. Sign and axis errors lead to physically wrong stiffness and failure predictions.
- Using isotropic assumptions. Composites behave very differently along and across fibres, and simplified isotropic models can mislead.
- Mesh-dependent damage results. Softening models without regularisation give results that change with element size.
- Applying coupon strengths directly to structures. Size effects, stress concentrations and manufacturing defects influence structural strength.
What good reporting looks like
A composites report states the material system and ply properties with sources, the layup and conventions, the modelling approach with justification, mesh details, failure criteria or damage parameters and their calibration, results such as stiffness, ply stresses, failure loads or damage patterns, comparison with test data or benchmarks, the sensitivity to uncertain parameters and limitations. It distinguishes first-ply failure from ultimate failure and indicates whether results were validated at coupon or structural scale.
An illustrative scenario
Hypothetical example written for explanation. It is not a client case, a result or a testimonial.
Imagine a researcher analysing a carbon-fibre panel under compression. Laminate theory suggests a stiffness and a first-ply failure load, and a layered shell model reproduces the stiffness measured in a test. A progressive damage model captures the onset of matrix cracking but overpredicts strength unless the shear parameters are adjusted using additional coupon data. The report presents both the validated stiffness and the calibrated strength prediction and notes that the strength prediction is valid only for the tested layup.
Questions to settle before you begin
- Which properties of the plies do I have, and from which tests?
- Which failure modes matter for my loading?
- How are layup and orientation conventions defined?
- At what scale can I validate: coupon, element or structure?
- How variable is my manufacturing process?
Key terms
- Laminate
- A stack of plies bonded together, each with a defined fibre orientation.
- Ply
- A single layer of fibre-reinforced material.
- Delamination
- Separation of adjacent plies.
- Cohesive zone model
- A representation of fracture through a traction-separation relation.
- Homogenisation
- Computing effective properties of a heterogeneous material.
Working together on Finite Element Analysis (FEA) & Structural Engineering projects
Structural and FEA engagements begin by clarifying what must be predicted, such as stress, stiffness, frequency or life, and which loads and supports are known. We ask for geometry, material data, load cases, connection details and any test measurements. A hand calculation or benchmark is prepared alongside the finite element model to cross-check it. Reports show mesh convergence, state assumptions about supports and materials, and give margins with their uncertainty. The work is research-level analysis and does not replace code-based design checks or certification by licensed professionals.
Frequently asked questions
Can you predict properties without material testing?
Micromechanics can estimate them, but estimates carry uncertainty. Testing remains the reference where decisions depend on exact values.
Do you need ply-level test data?
Reliable simulations need ply properties from tests or credible sources. Where they are missing, estimates can be made with micromechanics, with clear uncertainty.
Can you model impact on composites?
Impact damage modelling is possible but demanding, and feasibility depends on available data and tools.
Can you model composite repairs?
Simplified or detailed models of repairs can be considered, with attention to the adhesive layer and failure modes.
Do you perform composite testing?
No. The service analyses and models with data you supply; testing must be done by a suitable laboratory.
How is this service scoped and priced?
After your enquiry we review what you need, ask for missing information and send a written scope and quotation. Price depends on complexity, deliverables and timeline. See the project workflow.