A Guide for Customers of FEA Services
Abaqus INP Comprehensive Analyzer
Version 21.0
Peeking Under the Hood
A Guide for Design Engineers and Program Managers Why Understanding the Simulation Builds Confidence in the Decision
Joseph P. McFadden Sr.
The Holistic Analyst
Combating Engineering Mind Blindness
www.McFaddenCAE.com • McFadden@snet.net
April 2026
Developed in collaboration with Claude (Anthropic).
Introduction........................................................................ 1
1. Why Peeking Under the Hood Matters........................... 1
1.1 The Gap Between the Report and the Model............. 1
1.2 What You Can Verify Without Being an Analyst....... 1
1.3 Confidence Comes from Visibility............................. 1
2. What You Will See When You Open a Model................. 1
2.2 The Parts List — Is Everything in the Model?.......... 1
2.5 The Recommendations — What Did the Tool Find? 1
3. The Collaboration That Visibility Enables...................... 1
3.1 From Consumer to Collaborator............................... 1
3.2 The Questions Visibility Lets You Ask...................... 1
3.3 Building a Culture of Simulation Transparency....... 1
4. Your Five-Minute Review............................................... 1
Step 1 — Read the Banner (10 seconds).......................... 1
Step 2 — Count the Parts (30 seconds)........................... 1
Step 3 — Check the Materials (60 seconds).................... 1
Step 4 — Look at the Loads (90 seconds)....................... 1
Step 5 — Read the Recommendations (90 seconds)...... 1
A Final Word....................................................................... 1
Introduction
This guide is not for the analyst who builds the simulation. It is for the designer who designed the product being simulated, and for the program manager who will make a business or safety decision based on the simulation’s results. It is for anyone who relies on simulation output but has never opened the input file that produced it.
In most engineering organizations, simulation is a one-way street. The analyst receives a design, builds a model, runs the solver, and delivers a report. The designer reads the report and makes a design decision. The program manager reads the report and approves or rejects the product. At no point does anyone other than the analyst see what was actually inside the model — what materials were used, what boundary conditions were applied, which parts were included, and whether the simulation even represents the design it claims to simulate.
This is engineering mind blindness. It is the condition that develops when the consumers of simulation — the people who make decisions based on the results — have no way to verify that the simulation represents the problem they asked the analyst to solve. It is not a matter of trust. It is a matter of visibility. An analyst can be highly skilled, deeply experienced, and completely trustworthy, and the model can still contain an error that nobody catches because nobody other than the analyst can read it.
The Abaqus INP Comprehensive Analyzer was built to break this pattern. It reads the simulation input file without requiring an Abaqus license, organizes its contents into plain-language summaries and visual displays, and surfaces the information that designers and program managers need to verify that the simulation represents the physical problem. You do not need to understand Abaqus syntax. You do not need to know how to build a model. You need to know what your product looks like, what it is made of, and what it is supposed to survive — and this tool helps you confirm that the simulation reflects all three.
1. Why Peeking Under the Hood Matters
1.1 The Gap Between the Report and the Model
A simulation report is a summary. It shows stress contours, displacement plots, safety margins, and a conclusion. What it does not show is the model that produced those results. A stress contour can look correct and still be wrong if the material properties were entered in the wrong unit system. A safety margin can be positive and still be meaningless if the boundary conditions do not represent the physical test. A displacement plot can look plausible and still be fiction if a critical component was left out of the assembly.
The report does not show you these things because the report is a product of the model, not a description of the model. The analyst who wrote the report may have described the setup in the methodology section, but that description is the analyst’s interpretation of what the model contains. The model itself — the actual input file that the solver reads — is the ground truth. If the description says the model uses steel properties and the input file contains aluminum properties, the solver uses aluminum. If the description says all parts are included and the input file is missing the battery, the solver simulates a product without a battery. The report tells you what the analyst intended. The model tells you what the solver actually computed.
The ability to peek under the hood — to see the model directly, in plain language, without needing a solver license or analyst training — is what transforms a simulation consumer into a simulation collaborator. It gives you the ability to ask informed questions, to spot discrepancies between the design and the model, and to have the kind of engineering conversation with the analyst that produces better simulations and better decisions.
1.2 What You Can Verify Without Being an Analyst
You do not need to understand finite element theory to verify the most consequential aspects of a simulation model. You need your own domain knowledge — knowledge of the product, its materials, its operating environment, and its failure modes — applied to the information the Analyzer extracts from the input file. Here is what you can verify and why each matters.
What You Can Check
Why It Matters
Is every part of the product in the model?
A missing component means the simulation does not represent the physical product. The missing part’s mass, stiffness, and contact interactions are absent from the results.
Are the material assignments correct?
The wrong material on a component changes every result: stress, deflection, natural frequency, and failure prediction. A housing modeled as steel instead of polycarbonate is a different product.
Are the loads applied in the right direction?
A force pushing down instead of pulling up, or a pressure on the outside instead of the inside, produces a stress field that is the mirror image of reality. The magnitude may look correct while the sign is wrong everywhere.
Does the model represent the right test condition?
A model configured for a 1-meter drop at 4.43 m/s is a different simulation than a 1.5-meter drop at 5.42 m/s. The velocity, gravity, and drop orientation must match the test specification.
Are the support conditions physically correct?
A bracket modeled as rigidly fixed at all bolt holes behaves differently than one modeled with bolt preload and contact. The support conditions define how the structure resists the applied loads.
Is the unit system consistent?
A density value of 7850 means steel in SI units (kg/m³) but something impossibly dense in mm-tonne-s units (where steel is 7.85×10⁻⁹). A unit error shifts every result by orders of magnitude.
None of these checks require you to read Abaqus keywords or understand element formulations. They require you to know your product and apply that knowledge to the information the Analyzer presents. That knowledge is exactly what you bring to the collaboration that the analyst cannot provide alone.
1.3 Confidence Comes from Visibility
When a program manager signs off on a simulation report, that signature represents confidence that the simulation is a valid representation of the physical problem. Without visibility into the model, that confidence is based entirely on trust in the analyst and the reputation of the simulation process. With visibility, that confidence is based on evidence — on having seen the parts list and confirmed it matches the BOM, on having seen the material assignments and confirmed they match the spec sheet, on having seen the loads and confirmed they match the test requirement.
This distinction matters because trust alone does not catch errors. A trusted analyst working under schedule pressure can transpose two digits in a density value. An experienced analyst reusing a template from a previous project can carry forward a boundary condition that was correct for the old product and wrong for the new one. A skilled analyst coordinating with a design team can model the revision B geometry while the team has already moved to revision C. These are not competence failures. They are communication gaps — gaps between what the analyst intended and what the model contains, gaps between what the designer specified and what the analyst received, gaps between what the program expected and what was actually simulated. Visibility closes those gaps.
The goal is not to second-guess the analyst. The goal is to give every stakeholder the information they need to have an informed conversation about whether the simulation represents the engineering problem. The best analysts welcome this kind of scrutiny because it catches errors early, before they become test failures or field failures.
2. What You Will See When You Open a Model
When you load an INP file into the Analyzer and click Process, the tool parses every keyword in the file and organizes the results into tabs. You do not need to visit every tab. The following walkthrough covers the five things that matter most for a non-analyst reviewer, in the order you should check them.
2.1 The Model Type Banner — Is This the Right Kind of Simulation?
The first thing to read is the model type banner at the top of the window. It tells you whether the model is a Perturbation (vibration) analysis, an Impact (drop/crash) simulation, a Static (structural) analysis, or a Mixed model that combines more than one type. Compare this to the test specification or program requirement. If the requirement calls for a random vibration analysis and the banner reads Static, the model is solving the wrong problem.
Why this matters: The analysis type determines what physics the solver computes. A static analysis finds the equilibrium stress under constant loads. A modal analysis finds the natural frequencies and mode shapes. An impact analysis computes the transient response to a sudden velocity change. Each type uses different solver algorithms, different material properties, and different success criteria. Using the wrong type produces results that may look plausible but answer the wrong question.
2.2 The Parts List — Is Everything in the Model?
Open the Parts tab and read the list of parts. Compare this list to the product’s bill of materials. Every structural component that contributes mass, stiffness, or contact to the physical product should appear in the model. Select all parts and click View 3D to see the assembly in three dimensions. Rotate the model and confirm that the geometry looks like your product.
Why this matters: A missing part is not just an absent component — it is absent mass, absent stiffness, and absent contact. If the battery is not in the model, the product’s mass is wrong, the center of gravity is wrong, and the internal load path during a drop impact is wrong. If a structural bracket is missing, the stiffness of the assembly is wrong and the stress distribution in the surrounding components is wrong. The solver does not know that a part is missing. It computes the correct answer to the incomplete model. Only someone who knows the physical product can spot the gap.
The Islands button in the Parts tab tells you how many parts are disconnected from the rest of the assembly. An island count greater than zero means at least one part is floating in space with no mechanical connection to anything. In a physical product, every part is connected to something. In the model, a disconnected part is invisible to the solver and contributes nothing to the results.
2.3 The Materials — Are the Properties What You Specified?
Open the Materials tab and review the material names and properties. You do not need to understand every material keyword. What you need to confirm is that the materials assigned to each part match the materials in your design specification. If the spec calls for 6061-T6 aluminum and the model shows a generic aluminum with different density or modulus, the simulation is not testing your design — it is testing a different material.
Use the Material Consistency Review tool (Tools, Review Material Consistency) for a structured check. This tool shows every material in the model with its elastic modulus, Poisson ratio, density, and plasticity data in a single table. It flags any material that is missing required properties, has values outside expected ranges, or shows inconsistencies with the detected unit system.
Why this matters: Material properties drive every simulation result. The elastic modulus determines how much the structure deflects. The density determines the mass and therefore the natural frequencies and inertial forces. The yield stress determines when the material begins to deform permanently. A ten-percent error in modulus produces a ten-percent error in stiffness and a corresponding shift in every stress and displacement result. A three-order-of-magnitude error in density — common when the unit system is wrong — shifts every natural frequency by a factor of thirty.
2.4 The Loads and Boundary Conditions — Is the Test Setup Correct?
Open Tools, BC and Load Viewer. This is the single most powerful check available to a non-analyst reviewer. The viewer shows the entire assembly in 3D with colored arrows indicating every load and constraint in the model. Red arrows are applied forces. Yellow arrows are gravity. Cyan arrows are displacement constraints (fixed supports). You do not need to understand the numerical values. You need to confirm that the arrows are in the right places and pointing in the right directions.
For a drop simulation, the green arrow should point from the product toward the impact surface — not away from it. For a static analysis, the red force arrows should be at the locations where the physical loads are applied — not at the supports or at a random location. For a vibration model, the cyan constraint arrows should be at the physical mounting points — not floating in space.
Why this matters: The loads and boundary conditions define the problem the solver is solving. If the load is on the wrong face, the solver computes the stress from the wrong loading condition. If the support is at the wrong location, the solver computes the response of a differently supported structure. If the gravity direction is wrong, the solver computes the weight loading in the wrong orientation. These errors do not produce solver failures. They produce converged, plausible-looking results that answer the wrong question. The BC and Load Viewer makes them visible to anyone who knows where the loads and supports should be.
2.5 The Recommendations — What Did the Tool Find?
Open the Recommendations tab and read through the findings. Each recommendation is written in plain language with a severity level: Error (this will likely produce wrong results or a solver failure), Warning (this may produce incorrect results and should be reviewed), or Note (informational observation). You do not need to fix these items. You need to read them and, if any seem concerning, bring them to the analyst’s attention.
Why this matters: The Recommendations tab is the Analyzer’s independent assessment of the model’s completeness and consistency. It checks things that are tedious to verify manually: whether every part has a material, whether every material has the properties required for the analysis type, whether the contact definitions cover the interfaces that will be active during the event, and whether the output requests will produce the data needed for post-processing. A non-analyst reviewer does not need to understand every recommendation. But a recommendation that says a part is missing density, or that a contact pair references a surface that does not exist, is something that should be discussed with the analyst before the model is submitted.
3. The Collaboration That Visibility Enables
3.1 From Consumer to Collaborator
When a designer can open the simulation model and see that the housing material is polycarbonate with the correct glass fiber content, that the drop orientation matches the test specification, that all 47 components in the BOM appear in the parts list, and that the mounting points are constrained at the physical bolt locations — that designer is no longer a passive consumer of the analyst’s report. That designer is a collaborator who can confirm that the simulation represents the product as designed, or who can identify the specific discrepancy that needs to be corrected.
This is a fundamentally different relationship than one based on trust alone. Trust says: I believe the analyst built the model correctly because the analyst is experienced and competent. Collaboration says: I have verified that the model contains the materials I specified, the geometry I designed, and the loads from the test requirement, and I can confirm that the simulation represents the problem I need solved. Both relationships produce signed-off reports. Only one produces evidence-based confidence.
3.2 The Questions Visibility Lets You Ask
Without visibility into the model, the only questions a designer or program manager can ask are about the results: What is the maximum stress? Does it pass? What is the safety margin? These are important questions, but they are downstream questions. They assume the model is correct and ask only about its output.
With visibility, you can ask upstream questions — questions about the model itself that determine whether the results are meaningful. These are the questions that catch errors before they become test failures.
Upstream Question
What It Catches
I see 41 parts in the model but we have 47 in the BOM — which six are missing and why?
Missing components that affect mass, stiffness, or load path
The material for the housing shows E = 2100 MPa — shouldn’t that be 2400 for the 30% glass-filled grade we specified?
Material property errors that shift stress and deflection results
The drop orientation shows the velocity arrow pointing at the short edge — the test spec calls for a face-down drop. Is this the right test case?
Wrong test configuration that produces results for the wrong scenario
The boundary conditions show constraints at four points but the product mounts at six bolts. Are the two missing bolts intentional?
Under-constrained model that allows non-physical deformation
The Recommendations tab says three parts have no density defined. Does that affect the vibration results?
Missing mass that corrupts natural frequency extraction
The unit system shows tonne-mm-s but the test report uses SI. Is the conversion handled correctly?
Unit system mismatch that shifts every result by orders of magnitude
Every one of these questions comes from domain knowledge that the designer or program manager has and the analyst may not. The analyst knows how to build models. The designer knows what the product is made of. The program manager knows what test the product must pass. When all three people can see the model, all three forms of knowledge converge on the same set of facts. That convergence is what produces simulations that accurately represent reality.
3.3 Building a Culture of Simulation Transparency
The long-term value of peeking under the hood is not just catching individual errors. It is building a culture where simulation is a shared engineering artifact rather than a private analytical product. In organizations where only the analyst sees the model, simulation is a black box. Inputs go in, results come out, and everyone else takes the results on faith. In organizations where designers and managers routinely review the model’s contents — even briefly, even just the parts list and the loads — simulation becomes a transparent process that the entire team can verify and improve.
This culture shift has practical consequences. Analysts who know their models will be reviewed build more carefully. Designers who can see the model catch material and geometry errors before the solver runs. Program managers who understand what the simulation contains can write better test specifications and ask sharper questions during design reviews. The simulation process becomes faster (fewer re-runs caused by late-discovered errors), more reliable (more eyes catching more problems), and more trusted (confidence based on evidence rather than faith).
You do not need to review every model in detail. Even a five-minute check — confirming the parts count, verifying the material assignments, and glancing at the loads in the BC viewer — catches the most consequential errors and transforms your relationship with the simulation from passive consumption to active collaboration.
4. Your Five-Minute Review
If you have five minutes and a loaded model, here is exactly what to do and what to look for.
Step 1 — Read the Banner (10 seconds)
Is the model type what you expect? If the requirement calls for a vibration analysis, the banner should say Perturbation. If it calls for a drop test, the banner should say Impact. If it says the wrong type, stop and ask the analyst.
Step 2 — Count the Parts (30 seconds)
Open the Parts tab. Does the part count match your BOM? Click the Islands button. Is the count zero? If parts are missing or disconnected, note which ones and ask the analyst.
Step 3 — Check the Materials (60 seconds)
Open Tools, Review Material Consistency. Scan the table for your most critical materials. Is the modulus in the right range? Is density present for every material? Are there any issues flagged in red? If a material looks wrong, note the material name and the value that concerns you.
Step 4 — Look at the Loads (90 seconds)
Open Tools, BC and Load Viewer. Rotate the model. Are the arrows where you expect loads and supports to be? Are they pointing in the right directions? Does the overall setup look like the physical test? If something looks wrong, take a screenshot and ask the analyst.
Step 5 — Read the Recommendations (90 seconds)
Open the Recommendations tab. Read any items marked as Error or Warning. You do not need to understand every detail. If a recommendation mentions a missing property, an unresolved reference, or a configuration that will produce wrong results, note it and bring it to the analyst.
Five minutes. Five checks. And you now have more direct evidence about the simulation’s validity than you would get from reading the entire results report without seeing the model. That is the power of peeking under the hood.
A Final Word
The Abaqus INP Comprehensive Analyzer exists because simulation should not be opaque to the people whose decisions depend on it. A designer who cannot see the model cannot verify that it represents the design. A program manager who cannot read the model cannot confirm that it tests the right condition. An organization that treats simulation as a black box is making decisions on faith when it could be making them on evidence.
You do not need to become an analyst. You do not need to learn Abaqus. You need to take five minutes to look at the model, apply the product knowledge you already have, and confirm that what the solver is computing matches what the product actually is. That five-minute investment is the difference between trusting a report and understanding a simulation.
That understanding is what true collaboration looks like.
End of Guide
Abaqus INP Comprehensive Analyzer V21.0
www.McFaddenCAE.com • McFadden@snet.net
Developed in collaboration with Claude (Anthropic).
