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Engineering Simulation for Regulatory Compliance: What Can Be Simulated Before Testing?
A product can look finished, work well on the bench and still fail when it reaches a compliance laboratory.
That is not unusual.
The failure might come from heat building up around one component, a cable behaving like an antenna, a seal losing contact pressure, a bracket resonating at a particular frequency, or a battery transferring too much heat to an adjacent cell.
The problem is not necessarily that the product was poorly designed. Often, the issue is that some behaviours are difficult to see during normal development.
This is where simulation is useful.
Simulation gives engineers a way to investigate those behaviours before committing to formal testing. It can show where water is likely to enter an enclosure, where a PCB is generating electromagnetic energy, how a structure responds to vibration, or how heat moves through a battery pack.
There is an important qualification, though.
Simulation does not automatically replace a regulatory or compliance test.
For many standards, the physical test is still the required way of demonstrating compliance. Simulation is valuable because it can help identify problems earlier, improve the design before testing, and provide technical evidence around the design. In some areas, a properly developed and validated computational model can also form part of the formal regulatory evidence.
The FDA’s guidance on computational modelling for medical devices is a good example. It does not simply ask whether a model exists. It considers whether the model is credible for the decision it is being used to support.
So the more useful question is not:
“Can simulation replace the test?”
It is:
“What can we simulate to improve our confidence before the product reaches testing?”
Where simulation fits
Not every simulation has the same status from a regulatory point of view.
A useful way to think about it is:
| Type of use | What it means |
| Potential formal evidence | The applicable regulatory pathway can recognise computational analysis as part of the technical evidence, provided the model is sufficiently credible and the required verification and validation are addressed. |
| Compliance support | Physical testing is still expected, but simulation can be used to understand behaviour, establish margin and reduce the likelihood of failure. |
| Engineering risk reduction | The main purpose is to identify weaknesses and improve the design before qualification or certification. |
1. Can we simulate an IP rating?
Yes — although it is more accurate to say that we can simulate the conditions that matter to an IP rating.
IEC 60529 defines the degrees of protection provided by enclosures, including protection against solids and water.
For an outdoor electronic enclosure, for example, engineers may want to know:
- Where can water enter?
- Does the enclosure create a path towards the PCB?
- Is the gasket compressed sufficiently?
- What happens around connectors, vents and switches?
- Could enclosure deformation affect the seal?
- Where could dust accumulate?
A combination of CFD and FEA can investigate many of these questions before the physical test.
| Simulation | What can be investigated | Relevant area | Typical role |
| Water-ingress CFD | Water paths around openings and joints | IEC 60529 | Compliance support |
| Water-jet CFD | Flow and impact around enclosure features | IEC 60529 | Compliance support |
| Rain/spray CFD | Water exposure and trajectory | Environmental testing | Compliance support |
| Dust-particle CFD | Particle movement and ingress paths | IEC 60529 | Compliance support |
| Particle deposition | Areas where contamination may accumulate | IEC 60529 | Engineering support |
| Gasket compression FEA | Contact pressure and deformation | Enclosure sealing | Compliance support |
| Seal leakage modelling | Potential leakage paths | Enclosure sealing | Compliance support |
| Enclosure deformation FEA | Effect of deformation on sealing | IEC 60529 | Compliance support |
| Pressure-difference analysis | Internal/external pressure effects | Environmental protection | Engineering support |
| Vent-membrane airflow | Air exchange versus ingress protection | Enclosure design | Engineering support |
| Condensation modelling | Moisture accumulation inside enclosure | IEC 60068 | Compliance support |
The simulation does not, by itself, give the enclosure an IP rating.
What it can do is tell the engineering team where the design deserves attention before the test laboratory does.
That can be a very worthwhile distinction.
2. Thermal simulation: what happens when the product gets hot?
Temperature is one of the most common things engineers have to manage in compact electronic products.
A device can have an acceptable average temperature and still contain one component that is operating far too hot.
Thermal simulation can show this before the prototype goes through qualification.
| Simulation | What can be investigated | Relevant area | Typical role |
| Steady-state thermal CFD | Component and enclosure temperatures | IEC 60601-1, IEC 62368-1, IEC 61010-1 | Compliance support |
| Transient thermal simulation | Temperature over time | Product safety | Compliance support |
| PCB thermal analysis | Component and board temperatures | Electronics safety | Compliance support |
| Enclosure thermal CFD | Internal and accessible surface temperatures | IEC 62368-1 | Compliance support |
| Touch-temperature analysis | Accessible surface temperatures | Product safety | Compliance support |
| Natural-convection CFD | Cooling without forced airflow | Product safety | Compliance support |
| Forced-air CFD | Fan and airflow performance | Product safety | Compliance support |
| Heat-sink analysis | Heat transfer performance | Thermal design | Engineering support |
| Thermal-interface analysis | Contact and interface resistance | Thermal design | Engineering support |
| Thermal cycling simulation | Temperature distribution and cycling | IEC 60068 | Compliance support |
| Thermomechanical FEA | Stress caused by thermal expansion | Environmental qualification | Compliance support |
| Thermal-fatigue analysis | Repeated thermal loading | Reliability | Compliance support |
This is particularly useful when a design is crowded.
Moving a component by a few millimetres, changing the enclosure material or improving a thermal interface can sometimes have a much larger effect than expected.
Simulation makes those alternatives much easier to compare.
A simple example
Suppose an electronics enclosure contains a processor, power supply and several communication interfaces.
The first thermal simulation shows that the processor is fine, but one power device is creating a local hotspot next to a plastic wall.
There are several possible solutions:
- move the component,
- improve heat spreading,
- change the thermal interface,
- modify the airflow path,
- add a heat sink, or
- reduce the local heat load.
The important part is that the problem has been found before a compliance test.
3. EMC and EMI: finding the reason behind a failure
EMC is a particularly good example of where simulation can add value because laboratory results do not always explain the underlying mechanism.
A test may show that emissions are too high at one frequency.
The engineer then needs to work out why.
Simulation can help investigate:
- PCB radiation,
- cable coupling,
- return-current paths,
- enclosure apertures,
- connector coupling,
- common-mode currents,
- shielding performance and
- filter behaviour.
| Simulation | What it investigates | Relevant area | Typical role |
| 3D electromagnetic simulation | Radiated fields | CISPR / EMC | Pre-compliance |
| PCB EMI simulation | Radiation from PCB structures | CISPR / EMC | Pre-compliance |
| Near-field simulation | High-emission areas | EMC development | Engineering support |
| Cable radiation modelling | Common-mode radiation | Automotive / CISPR EMC | Pre-compliance |
| Cable coupling simulation | Noise entering or leaving through harnesses | IEC 61000 | Pre-compliance |
| Enclosure radiation simulation | Leakage through housing | EMC | Pre-compliance |
| Aperture/slot simulation | Radiation through openings | EMC | Pre-compliance |
| Shielding-effectiveness analysis | Enclosure shielding | EMC | Pre-compliance |
| Filter simulation | EMI filter performance | EMC | Engineering support |
| Common-mode current simulation | High-frequency current paths | EMC | Engineering support |
| Differential-mode analysis | High-frequency noise | EMC | Engineering support |
| Ground/return-path simulation | Unwanted current paths | EMC | Engineering support |
| Connector EM simulation | High-frequency coupling | EMC | Engineering support |
| Radiated RF immunity modelling | RF coupling into the device | IEC 61000-4-3 | Compliance support |
| Conducted RF coupling | RF entering through cables | IEC 61000-4-6 | Compliance support |
| ESD current-path modelling | Discharge-current paths | IEC 61000-4-2 | Compliance support |
| EFT coupling simulation | Fast transient coupling | IEC 61000-4-4 | Compliance support |
| Surge propagation analysis | Voltage/current distribution | IEC 61000-4-5 | Compliance support |
This is why EMC simulation can be particularly useful during development.
A test result may tell you:
“There is excessive radiation at 480 MHz.”
A useful simulation may help answer:
“The high-frequency return current is coupling into the cable shield and the cable is radiating.”
That second answer gives the designer something to change.
4. Electrical safety and fault conditions
Normal operation is only part of the story.
Products may also need to behave safely when the input voltage is abnormal, a component fails, a short circuit occurs or a protection mechanism operates.
Electrical simulation can be used to explore those situations.
| Simulation | What it investigates | Relevant area | Typical role |
| Short-circuit simulation | Fault current and energy | Product safety | Compliance support |
| Overvoltage simulation | Component and insulation stress | Product safety | Compliance support |
| Inrush-current simulation | Startup electrical stress | Electrical safety | Engineering support |
| Brownout simulation | System behaviour during undervoltage | Electrical qualification | Engineering support |
| Leakage-current simulation | Current under normal/fault conditions | IEC 60601-1 | Compliance support |
| Touch-current simulation | Accessible current | IEC safety | Compliance support |
| Earth-fault simulation | Fault-current paths | Electrical safety | Compliance support |
| Electric-field simulation | Dielectric stress | Insulation coordination | Compliance support |
| Insulation analysis | Voltage stress through insulation | Product safety | Compliance support |
| Protection-device simulation | Fuse/protection response | Product safety | Compliance support |
| Power-transient simulation | Response to electrical disturbances | IEC / automotive | Engineering support |
This type of analysis is often most useful when it is tied directly to a known risk.
Instead of modelling a fault just because it is possible, the engineer can ask:
What happens if this component fails in the worst credible way?
That tends to produce much more useful work.
5. Structural FEA, shock and vibration
Mechanical failures are often caused by dynamic behaviour rather than simple static loading.
A product may survive a static load comfortably but develop high stresses when its natural frequency is excited.
This is why modal and vibration analysis are so useful.
| Simulation | What it evaluates | Relevant area | Typical role |
| Static structural FEA | Stress and deformation | Product qualification | Compliance support |
| Modal analysis | Natural frequencies | IEC 60068 / IEC 61373 / ISO 16750 | Compliance support |
| Harmonic response | Response at specific frequencies | Vibration qualification | Compliance support |
| Random vibration analysis | Response to vibration PSD | IEC 60068 / IEC 61373 | Compliance support |
| Shock simulation | Transient structural response | IEC 60068 | Compliance support |
| Drop simulation | Impact loading | Product/environmental qualification | Compliance support |
| Fatigue analysis | Life under cyclic loading | Environmental qualification | Compliance support |
| PCB structural FEA | Board deformation | Electronics qualification | Compliance support |
| Bracket analysis | Mounting strength | Environmental qualification | Compliance support |
| Fastener analysis | Joint loading | Mechanical design | Engineering support |
| Connector analysis | Retention and deformation | Product qualification | Engineering support |
| Buckling analysis | Structural instability | Mechanical qualification | Compliance support |
| Thermomechanical FEA | Combined temperature/mechanical stress | Environmental qualification | Compliance support |
A good example is railway equipment.
IEC 61373:2026 includes finite element analysis for structural parts in its revised treatment of shock and vibration.
That is a useful illustration of the direction engineering qualification is taking: simulation and physical testing can work together rather than being treated as completely separate activities.
6. Thermal cycling and environmental conditions
Temperature changes can create mechanical problems that are not obvious when the product is considered at one temperature.
Different materials expand at different rates. Repeated cycling can therefore put stress into:
- solder joints,
- PCBs,
- connectors,
- seals,
- housings,
- adhesives and
- mechanical interfaces.
A coupled thermal-structural model can be used to investigate these effects.
| Simulation | What it shows | Typical purpose |
| Thermal cycling | Temperature distribution over time | Environmental qualification |
| Thermal expansion | Dimensional changes | Design verification |
| Thermomechanical stress | Stress from different material expansion | Reliability |
| Solder-joint fatigue modelling | Repeated thermal stress | Electronics reliability |
| Seal deformation | Temperature-dependent sealing | Environmental protection |
| Housing expansion | Interface movement | Mechanical design |
| Material-property sensitivity | Effect of temperature-dependent properties | Engineering confidence |
The value here is less about predicting a single pass/fail number and more about finding the parts of the design that need attention.
7. Batteries: when thermal, electrical and mechanical behaviour meet
Battery systems are a particularly good example of multiphysics engineering.
Electrical current creates heat. Temperature affects behaviour. Cells can expand. Abnormal events can generate gases and pressure. In some failure conditions, heat can propagate from one cell to another.
That combination is difficult to understand from one discipline alone.
| Simulation | What it investigates | Relevant area | Typical role |
| Cell thermal simulation | Cell temperature | IEC 62133 / IEC 62619 | Compliance support |
| Pack thermal simulation | Temperature distribution | Battery safety | Compliance support |
| Electrothermal modelling | Electrical and thermal interaction | Battery safety | Compliance support |
| Cell-to-cell propagation | Thermal propagation | Battery safety | Compliance support |
| Thermal-runaway modelling | Abnormal thermal behaviour | Battery qualification | Compliance support |
| Cooling CFD | Cooling performance | Battery systems | Engineering support |
| Enclosure CFD | Airflow and heat transfer | Battery safety | Engineering support |
| Vent-gas CFD | Gas discharge paths | Battery safety | Compliance support |
| Pressure-relief simulation | Venting behaviour | Battery safety | Engineering support |
| Busbar thermal analysis | Joule heating | Battery systems | Engineering support |
| Short-circuit simulation | Fault current and heat generation | Battery safety | Compliance support |
| Battery mechanical FEA | Crush and deformation | Battery qualification | Compliance support |
| Vibration analysis | Structural durability | IEC 62133 / ISO 16750 | Compliance support |
| Fire/heat propagation CFD | Heat and flame spread | Battery safety | Engineering support |
| Cooling-failure simulation | Worst-case thermal condition | Safety assessment | Compliance support |
A model can, for example, help answer whether heat from a failed cell is likely to reach neighbouring cells quickly enough to become a larger problem.
Physical testing remains important, but simulation gives the engineering team somewhere to start.
8. RF exposure, antennas and human interaction
RF simulation has a different relationship with regulation from ordinary EMC work.
Engineers may need to understand how an antenna behaves near a person’s body, how an enclosure changes antenna performance or how much RF energy is absorbed by tissue.
| Simulation | What it investigates | Relevant area | Typical role |
| Antenna radiation pattern | Gain and directivity | FCC / RED / ETSI | Compliance support |
| Antenna efficiency | RF performance | RF regulations | Engineering support |
| Antenna detuning | Body/enclosure effects | RF regulations | Compliance support |
| Near-field simulation | Local RF fields | RF exposure | Compliance support |
| SAR simulation | RF energy absorbed by tissue | FCC / applicable exposure frameworks | Potential formal evidence |
| Whole-body exposure modelling | Absorbed RF energy | RF exposure | Compliance support |
| Maximum permissible exposure modelling | Exposure levels | FCC / RF frameworks | Compliance support |
| Human-body coupling | Wearable interaction | RF exposure | Compliance support |
| Implant interaction modelling | Device/tissue interaction | Medical/RF | Engineering/regulatory support |
| Wireless coexistence simulation | Radio-to-radio interference | RED / ETSI | Pre-compliance |
This is an area where computational modelling can, under the right pathway, become more than a design tool.
The exact requirements depend on the device, frequency range, jurisdiction and assessment method.
9. Medical devices: one of the clearest regulatory examples
Medical-device development is probably the strongest example of a regulatory environment where computational modelling can become formal evidence.
The FDA’s guidance on computational modelling and simulation focuses on the credibility of the model for its intended context of use. That includes understanding how the model was verified and validated and how much the regulatory decision depends on its results.
Possible applications include:
| Simulation | Example application | Potential role |
| Structural FEA | Implant strength | Regulatory evidence / support |
| Fatigue FEA | Implant lifetime | Regulatory evidence / support |
| Contact mechanics | Tissue/device interaction | Regulatory evidence / support |
| CFD | Blood flow | Regulatory evidence / support |
| CFD | Catheter or valve flow | Regulatory evidence / support |
| Fluid-structure interaction | Valve/tissue interaction | Regulatory evidence / support |
| Thermal modelling | Device-generated heating | Regulatory evidence / support |
| Bioheat modelling | Tissue temperature | Regulatory evidence / support |
| Electromagnetic modelling | RF/device interaction | Regulatory evidence / support |
| Particle-flow modelling | Aerosol delivery | Regulatory evidence / support |
| Patient-specific modelling | Individual patient prediction | Regulatory evidence / support |
This is a good example of why “simulation” and “regulatory evidence” should not be treated as completely unrelated subjects.
There are situations where the computational model itself becomes part of the technical argument.
But that comes with a much higher expectation of model credibility.
10. Pressure equipment and design by analysis
Pressure equipment is another area worth highlighting because the relationship between simulation and regulation can be more direct.
The UK Pressure Equipment (Safety) Regulations 2016 recognise design by formula, design by analysis and design by fracture mechanics as possible approaches to establishing adequate strength, depending on the circumstances.
That means structural analysis can potentially be part of the recognised design methodology rather than simply a preliminary engineering exercise.
Typical analyses include:
| Simulation | What it evaluates | Potential role |
| Pressure-vessel FEA | Stress under internal pressure | Formal design analysis |
| Pressure-boundary analysis | Structural integrity | Formal design analysis |
| Thermal-pressure FEA | Combined loading | Formal design analysis |
| Nozzle analysis | Local stress | Design substantiation |
| Fatigue analysis | Cyclic pressure | Design substantiation |
| Buckling analysis | External pressure/vacuum | Design substantiation |
| Fracture mechanics | Crack tolerance | Design substantiation |
| Pipe stress analysis | Pressure and thermal loads | Design substantiation |
| CFD pressure-drop modelling | Flow behaviour | Engineering support |
| Relief-flow simulation | Flow capacity | Engineering support |
This is one of the strongest examples of why the phrase “simulation for compliance” needs some context.
Sometimes simulation supports the compliance test.
Sometimes it supports the risk analysis.
And in some engineering frameworks, analysis can form part of the design substantiation itself.
11. Automotive electronics
Automotive electronics are exposed to a combination of vibration, temperature, electrical disturbances and EMC.
ISO 16750 addresses environmental conditions and testing for electrical and electronic equipment used in road vehicles. Automotive EMC requirements can also involve UN Regulation No. 10 and related standards.
That creates a wide range of useful simulation opportunities.
| Simulation | Application | Relevant area |
| ECU thermal CFD | Electronics cooling | ISO 16750 |
| Vibration FEA | Mechanical response | ISO 16750 |
| Shock FEA | Shock response | ISO 16750 |
| Thermal cycling | Thermomechanical stress | ISO 16750 |
| Electrical transient simulation | Supply disturbances | ISO 16750 |
| PCB vibration analysis | Board durability | ISO 16750 |
| Cable EMC modelling | Harness coupling | Automotive EMC / UN R10 |
| ECU EMC simulation | Radiated/conducted behaviour | Automotive EMC |
| Battery thermal simulation | EV battery systems | Battery qualification |
| Battery mechanical FEA | Structural integrity | EV battery safety |
| Sensor EM simulation | Sensor behaviour/interference | Automotive EMC/RF |
This is a good example of why multiphysics simulation matters. The electronic module is not experiencing one environmental stress at a time.
12. Rail equipment
Railway equipment is another area where vibration and structural simulation can be highly relevant.
| Simulation | What it investigates | Typical standard/application |
| Modal analysis | Natural frequencies | IEC 61373 |
| Random vibration analysis | Structural response | IEC 61373 |
| Shock simulation | Mechanical loads | IEC 61373 |
| Mounting analysis | Mounting integrity | IEC 61373 |
| Fatigue analysis | Long-term vibration | Railway qualification |
| PCB structural analysis | Electronics durability | Railway electronics |
| Cable/harness vibration | Connection durability | Railway qualification |
| Thermal analysis | Equipment temperature | Railway environmental qualification |
| EMC simulation | Electromagnetic behaviour | Railway EMC |
The 2026 edition of IEC 61373 is particularly noteworthy because it includes FEA provisions for structural parts.
13. Aerospace and aviation
Aerospace equipment is exposed to some of the most demanding combinations of environmental conditions.
Simulation can be used to investigate:
| Simulation | Application | Relevant area |
| Thermal analysis | Equipment temperature | DO-160 / aviation qualification |
| Thermal-cycle simulation | Environmental stress | DO-160 |
| Altitude/pressure simulation | Atmospheric conditions | DO-160 |
| Vibration FEA | Structural response | DO-160 |
| Shock simulation | Mechanical integrity | DO-160 |
| Water-ingress CFD | Environmental exposure | DO-160 |
| Humidity modelling | Moisture exposure | DO-160 |
| EMC simulation | Equipment compatibility | DO-160 |
| Lightning coupling | Electromagnetic transients | Aerospace |
| HIRF simulation | RF susceptibility | Aerospace |
| Structural FEA | Equipment strength | Certification substantiation |
| Fatigue modelling | Life assessment | Aerospace |
| Thermal-stress analysis | Combined thermal/mechanical loads | Aerospace |
| Cooling-flow CFD | Equipment cooling | Aerospace |
The exact role of analysis depends on the certification basis and approval pathway, so this is another area where the model should be considered part of a larger substantiation strategy rather than treated as a standalone certificate.
14. Machinery, robotics and functional safety
Simulation is also useful when the main concern is not structural or thermal performance but what happens when a machine or control system encounters a hazardous condition.
| Simulation/model | What it investigates | Relevant area |
| Collision simulation | Collision hazards | Machinery safety |
| Robot workspace simulation | Hazard zones | ISO 10218 |
| Guard reach simulation | Accessibility | Machinery safety |
| Mechanical FEA | Structural integrity | Machinery safety |
| Dynamic mechanism simulation | Motion hazards | Machinery safety |
| Brake-response simulation | Stopping behaviour | Machinery safety |
| Safety-distance analysis | Guarding distances | Machinery safety |
| Fault-tree analysis | Hazard pathways | Functional safety |
| FMEA/FMEDA modelling | Failure behaviour | Functional safety |
| Fault-injection simulation | Safety mechanisms | ISO 26262 / IEC 61508 |
| Sensor-failure scenarios | Safe response | Functional safety |
| Communication-fault scenarios | Safe-state behaviour | Functional safety |
These models are usually not a substitute for the full machinery or functional-safety assessment. Their value is in showing how the system behaves when a fault or hazardous scenario occurs.
15. Fire, smoke and hazardous releases
Some products and systems need to be understood under very abnormal conditions.
Examples include batteries, process equipment and enclosures where a fire or hazardous release could have consequences outside the product itself.
| Simulation | Application | Typical role |
| Fire propagation CFD | Fire spread | Risk assessment |
| Smoke-flow CFD | Smoke movement | Safety analysis |
| Heat-release modelling | Thermal loading | Fire analysis |
| Thermal decomposition modelling | Material behaviour | Fire analysis |
| Flame propagation modelling | Material/fire behaviour | Safety assessment |
| Ventilation CFD | Removal of smoke or gas | Safety engineering |
| Gas-dispersion CFD | Hazardous release | Process safety |
| Fire-barrier thermal FEA | Barrier performance | Engineering support |
| Battery fire modelling | Heat and flame propagation | Battery safety |
These are generally better presented as supporting analyses unless the applicable regulatory framework specifically recognises the computational approach.
16. Fluid and process systems
CFD also has a role in regulated and safety-critical industrial systems.
| Simulation | What it investigates | Application |
| Pressure-drop CFD | System resistance | Industrial/process systems |
| Flow-distribution CFD | Flow uniformity | Process equipment |
| Valve CFD | Flow behaviour | Fluid systems |
| Pump CFD | Hydraulic performance | Industrial equipment |
| Cavitation simulation | Cavitation risk | Pumps/valves |
| Erosion modelling | Material loss | Process equipment |
| Leakage simulation | Fluid containment | Safety |
| Two-phase CFD | Gas/liquid behaviour | Process systems |
| Gas-dispersion CFD | Hazardous release | Process safety |
| Ventilation CFD | Air movement | Industrial safety |
| Heat-exchanger CFD | Thermal performance | Industrial equipment |
| Combustion CFD | Thermal/combustion behaviour | Energy/process systems |
| Exhaust dispersion | Emission dispersion | Environmental engineering |
These applications become particularly useful when the design contains interacting fluid, thermal and structural effects.
17. A useful way to look at common EMC tests
Rather than starting with the simulation software, it can be useful to start with the physical test and work backwards.
| Physical test | What can be investigated with simulation beforehand? |
| IEC 61000-4-2: ESD | ESD current paths and field coupling |
| IEC 61000-4-3: Radiated RF | RF field coupling into the product |
| IEC 61000-4-4: EFT | Transient coupling |
| IEC 61000-4-5: Surge | Surge propagation |
| IEC 61000-4-6: Conducted RF | Cable/common-mode coupling |
| IEC 61000-4-8: Power-frequency magnetic field | Magnetic-field coupling |
| IEC 61000-4-9: Pulsed magnetic field | Transient magnetic response |
| IEC 61000-4-11: Voltage dips | Power-system response |
| IEC 61000-4-13: Harmonics/interharmonics | Power-quality behaviour |
| IEC 61000-4-16: Conducted disturbances | Circuit/network response |
The simulation does not necessarily answer the final compliance question.
It can, however, answer a much more practical question:
What part of the design is likely to be responsible for the failure?
18. The most useful simulations may be the ones that look at failure
There is a difference between asking whether a product works and asking how it might fail.
That second question is where simulation can become particularly powerful.
| Failure scenario | Possible simulation |
| Cooling fan stops | Thermal CFD |
| Vent becomes blocked | CFD + thermal analysis |
| Water reaches the enclosure | Multiphase CFD |
| Seal loses compression | Contact FEA |
| PCB develops a hotspot | Thermal FEA |
| Battery cell overheats | Electrothermal modelling |
| Thermal runaway propagates | Thermal CFD |
| Enclosure is dropped | Explicit FEA |
| Product reaches resonance | Modal/vibration analysis |
| Cable becomes an antenna | 3D EM simulation |
| ESD enters through an aperture | EM/transient simulation |
| Power supply experiences a surge | Circuit/transient simulation |
| Pressure rises unexpectedly | Pressure FEA |
| Component fails short-circuit | Electrical/thermal simulation |
| Sensor fails | Functional/system simulation |
| Communication link fails | System/fault simulation |
This is where simulation fits particularly well with engineering risk assessment.
Instead of waiting for the physical prototype to demonstrate a failure mode, the team can deliberately investigate it earlier.
So, can simulation actually satisfy a regulation?
Sometimes analysis can form part of the formal evidence. Sometimes it cannot.
There is no single answer that applies across every industry.
| Application | Can simulation replace the prescribed physical test? | Typical role |
| IP rating | Generally no | Predict ingress paths and improve the enclosure |
| Thermal safety | Generally no | Predict temperature and establish margin |
| EMC | Generally no | Identify coupling and radiation mechanisms |
| Vibration | Generally no | Identify resonance, stress and fatigue risk |
| Battery qualification | Generally no | Investigate thermal, mechanical and electrical behaviour |
| RF exposure | In some pathways, computational evidence can contribute | Exposure and SAR assessment |
| Medical-device modelling | Potentially, depending on application and regulatory pathway | Supporting or formal evidence |
| Pressure equipment | In some frameworks, analysis can be part of design substantiation | Design by analysis |
| Functional safety | Simulation is an important engineering method | Fault and safety analysis |
| Machinery safety | Usually supporting evidence | Hazard and risk reduction |
That is why we should be careful with the phrase “simulation for compliance”.
The better description is often:
simulation that supports compliance, verification and regulatory confidence.
Simulation needs evidence behind it too
A simulation result is not automatically trustworthy because the mesh is fine or the contour plot looks convincing.
The model needs to be appropriate for the question being asked.
Depending on the application, that may involve:
- checking numerical convergence,
- verifying the implementation,
- using appropriate material properties,
- validating assumptions,
- comparing results with physical measurements,
- assessing sensitivity to uncertain inputs,
- documenting assumptions and limitations, and
- establishing the credibility needed for the decision.
This becomes particularly important when the simulation is intended to support a regulatory submission.
The FDA’s approach to medical-device CM&S is a useful example because it explicitly considers the context of use and the level of credibility needed for the decision.
In other words, the question is not simply:
“Did we run a simulation?”
It is:
“Is this model credible enough for the decision we are making with it?”
A better product-development workflow
A practical way to use simulation is to bring it into the development process well before formal testing.
A typical workflow might look like this:
Requirement → Risk → Simulation → Design change → Physical verification → Regulatory evidence
For an IP-rated enclosure:
IP requirement
↓
Identify potential ingress paths
↓
CFD and sealing analysis
↓
Modify enclosure/gasket
↓
Physical IP test
↓
Compliance documentation
For EMC:
EMC requirement
↓
Identify likely coupling paths
↓
EM simulation
↓
Improve PCB, grounding, filtering or shielding
↓
EMC test
↓
Compliance documentation
For thermal safety:
Temperature requirement
↓
Identify worst-case operating condition
↓
Thermal CFD/FEA
↓
Improve cooling or component arrangement
↓
Physical verification
↓
Compliance evidence
And for a medical device where computational modelling is part of the regulatory strategy:
Regulatory question
↓
Define the context of use
↓
Develop the computational model
↓
Verify and validate
↓
Assess model credibility
↓
Use the results within the regulatory submission where appropriate
The common idea is simple:
Don’t wait until the compliance test to learn something important about the product.
What this means for engineering teams
Simulation is most useful when it is connected to a real engineering question.
Not:
“Let’s run CFD.”
But:
“We need to understand whether water can reach this connector during the IP test.”
Not:
“Let’s run FEA.”
But:
“We need to know whether this bracket will resonate during the vibration qualification.”
Not:
“Let’s run an EMC model.”
But:
“We are seeing an emission peak around this frequency and need to understand where the energy is coming from.”
That change in thinking tends to produce much more useful engineering work.
Where Twelvium can contribute
At Twelvium, we approach simulation as part of the engineering process rather than as a standalone exercise.
Depending on the product and the question, that can include:
Thermal and CFD analysis
Understanding heat generation, airflow, cooling, hotspots, environmental conditions and fluid behaviour.
Structural and mechanical simulation
Investigating stress, deformation, resonance, vibration, shock and fatigue.
EMC and EMI simulation
Looking at electromagnetic coupling, radiation, shielding, PCB behaviour and cable effects.
Multiphysics analysis
Bringing thermal, structural, fluid and electromagnetic behaviour together where the problem cannot realistically be understood from one discipline alone.
Failure and risk analysis
Using simulation to investigate credible abnormal conditions and potential failure mechanisms.
For regulated products, the analysis should be planned around the intended verification and regulatory pathway rather than added as an afterthought.
The main idea
Physical compliance testing still matters.
But it is expensive to use the laboratory as the place where the engineering team discovers how a product behaves.
Simulation gives the team another option.
You can investigate water ingress before an IP test.
You can find thermal hotspots before a temperature test.
You can identify resonance before a vibration campaign.
You can trace electromagnetic coupling before EMC testing.
You can investigate abnormal battery behaviour before qualification.
You can assess RF exposure computationally.
You can use FEA and CFD as part of medical-device regulatory evidence where the applicable pathway allows it.
And in some engineering frameworks, analysis can become part of the formal design substantiation itself.
The point is not to replace physical testing with a simulation.
The point is to arrive at physical testing with a better-engineered product and a better understanding of what the test is actually trying to prove.
That can mean fewer surprises, fewer redesigns and a much more controlled path from engineering design to compliance.
A note on standards and regulatory requirements
The examples in this article are intended to illustrate where simulation can contribute to engineering verification, validation and regulatory confidence. They are not a universal compliance matrix.
The exact requirements depend on the product, market, jurisdiction, applicable standard and certification pathway.
Where simulation is intended to become formal regulatory evidence, the model’s context of use, verification, validation, credibility and limitations need to be addressed appropriately.
The regulatory use of computational modelling in medical-device submissions is one example where this approach is explicitly recognised.
References
- IEC 60529, Degrees of protection provided by enclosures (IP Code).
- IEC 61373:2026, Railway applications — Rolling stock equipment — Shock and vibration tests.
- U.S. Food and Drug Administration, Assessing the Credibility of Computational Modeling and Simulation in Medical Device Submissions.
- ASME V&V 40, Assessing Credibility of Computational Modeling through Verification and Validation: Application to Medical Devices.
- UK Pressure Equipment (Safety) Regulations 2016.