How to Assess Your Models for Structural Weakness with Onshape

By Sandeep U.

For decades, structural analysis, or Finite Element Analysis (FEA), has been the engineering equivalent of a final exam graded with a red pen. It was a late-stage, high-stakes process performed by a select group of specialists on powerful, expensive hardware. A design was created, handed off, and everyone held their breath, waiting for the pass/fail verdict. This fragmented, time-consuming workflow created a bottleneck, stifling innovation and slowing time-to-market.

But what if analysis wasn’t a final exam, but a friendly tutor, offering guidance from the very beginning? That’s the paradigm shift being driven by Onshape Simulation. By leveraging the cloud and rethinking the entire workflow, Onshape has transformed a complex, siloed discipline into an intuitive, agile tool that empowers every designer to build better products, faster.

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Here’s how Onshape’s key differentiators are making it happen.

Power in the Cloud, Simplicity on the Screen

Onshape’s cloud-native architecture is the engine that drives these innovations. By offloading all the heavy computation to powerful cloud servers, it eliminates the need for expensive, specialized workstations. If you have a web browser, you have a high-performance simulation machine.

Mates, Not Manual Connections

Setting up the connections between parts in a large assembly is one of the most tedious and error-prone tasks in traditional FEA. Analysts spend hours manually defining contact sets, telling the software which faces are bonded, which can slide, and which can separate.

Onshape’s mating system makes this a thing of the past. The same high-level mates you use to build your assembly—like Fastened, Revolute, or Slider—are automatically translated into the corresponding physical behaviors for the simulation. When you define a Revolute mate for a hinge, the simulation automatically understands it as a pin joint. By simply building a kinematically correct CAD model, you’ve already done the vast majority of the simulation setup. This intelligent automation doesn't just save time; it democratizes assembly analysis, making it accessible to any designer who can build an Onshape assembly.

A "Meshless" Experience for the User

For non-specialists, the biggest hurdle in FEA has always been meshing—the complex process of breaking a model down into a grid of finite elements. A poor mesh leads to inaccurate results or failed analyses, and generating a good one requires deep expertise.

Onshape makes this entire problem disappear for the user. From the designer's perspective, the experience is "meshless." There are no complex controls for element size or quality. This strategic abstraction shifts the focus from the complex procedure of how to run an analysis to the valuable engineering insights of what the results mean.

The CAD Model and Simulation Model are Integrated

The most profound difference in Onshape is this: the simulation is not  an export of your design; it is your design. In traditional workflows, engineers export their CAD model, which is then simplified, meshed, and analyzed in a separate environment. Any change to the original design instantly makes the analysis model obsolete, a frequent and costly source of error.

Onshape eliminates this completely. Simulation is a feature of the Assembly environment. When you change a dimension, swap a part, or modify a material, the simulation results update automatically. This creates a live, interactive feedback loop. You can ask "what if?" and see the structural impact in minutes, not days. This transforms analysis from a validation gate into a real-time design guide. 

Analysis Simplified: Linear Statics and Inertial Relief

The foundation of Onshape Simulation is Linear Static analysis. This is the workhorse of the engineering world, used to calculate stress, displacement, and strain on parts and assemblies that are under static (i.e., constant, unchanging) loads. It answers the most fundamental design questions: "Will it break?" and "Will it bend too much?".

TECH TIP: Linear Static Analyses with Bearing Loads

A key requirement for standard linear static analysis is that the model must be fully constrained—in layman's terms, it needs to be "held down" so it doesn't fly away when a load is applied. If it's not, the simulation will fail. This presents a major challenge when analyzing systems that are not fixed to the ground, like an aircraft in flight, a satellite in orbit, or even a sub-assembly that is meant to be in equilibrium within a larger machine.

The common, and dangerous, mistake made by non-specialists is to add artificial constraints to the model just to make the simulation run. Forcing a model to be fixed when it should be free fundamentally changes its behavior and can produce results that are wildly inaccurate and misleading, giving a false sense of security.

This is where Inertial Relief comes in. It is an advanced technique specifically for analyzing unconstrained or under-constrained bodies in static equilibrium. It works by automatically calculating a set of inertial forces that perfectly balance the applied loads, allowing the solver to find a stable solution without artificial constraints. In traditional FEA software, setting up an inertial relief analysis is an expert-level task.

In Onshape, it’s a single checkbox.

This is a perfect example of Onshape’s philosophy: democratize powerful tools by abstracting their complexity. By enabling this feature with one click, Onshape empowers every designer to accurately analyze a whole new class of real-world problems. 

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