The ESRD Blog Archives - Page 2 of 5

Variational Crimes and Refloating the Costa Concordia

Mar 25, 2025

In one of my conference presentations, I discussed variational crimes, noting that using point forces and point constraints in finite element analysis serves as examples of such crimes. In the question-and-answer session, I was asked: “If using point constraints is a variational crime, then how is it possible that the structure designed to refloat the Costa Concordia was full of those crimes and yet it worked just fine.” This question presented an opportunity for me to explain that finite element modeling (FEM) and finite element analysis (FEA) are complementary methods when analysts correctly understand their respective domains of application and use them accordingly. However, problems arise when FEM is used outside its scope, which is an all too frequent error.

Why Is Solution Verification Necessary?

Feb 24, 2025

We at ESRD preach and practice solution verification. We believe that reporting data computed by an approximate method is incomplete without providing an estimate of the size of the relative error. This simple and self-evident statement tends to trigger fierce resistance from those who were schooled in the use of legacy finite element modeling tools. But why?

Chaos in the Brickyard Revisited

Jan 15, 2025

In a letter published in Science in 1963, Bernard K. Forscher used the metaphor of building edifices to represent the construction of scientific models, also called laws. These models explain observed phenomena and make predictions beyond the observations made.
Building models consistent with the science of numerical simulation should never be confused with finite element modeling, an activity rooted in pre-1970s thinking. We should keep Forscher’s metaphor in mind when evaluating claims about the benefits AI integration is expected to bring to numerical simulation.

Isogeometric Analysis (IGA)

Dec 9, 2024

Contrary to various claims, IGA is not a new paradigm in the numerical approximation of partial differential equations; it is simply an alternative implementation of the p-version of the finite element method. IGA is one possible implementation of the p-version of the finite element method. Its distinguishing features are: (a) it retains the CAD geometry, (b) the basis functions are the same as those used for CAD representation, typically B-splines or NURBS, and (c) it provides for the enforcement of the inter-element continuity of the derivatives of the basis functions.

XAI Will Force Clear Thinking About the Nature of Mathematical Models

Nov 15, 2023

It is generally recognized that explainable artificial intelligence (XAI) will play an important role in numerical simulation where it will impose the requirements of reliability, traceability, and auditability. These requirements will necessitate clear thinking about the nature of mathematical models, the trustworthiness of their predictions, and ways to improve their reliability.

Meshless Methods

Nov 7, 2024

Meshless methods, also known as mesh-free methods, are computational techniques used for the approximation of the solutions of partial differential equations in the engineering and applied sciences. The advertised advantage of the method is that users do not have to worry about meshing. However, eliminating the meshing problem has introduced other, more complex issues. Oftentimes, advocates of meshless methods fail to mention their numerous disadvantages.

A Critique of the World Wide Failure Exercise

Oct 3, 2024

The World-Wide Failure Exercise (WWFE) was an international research project with the goal of assessing the predictive performance of competing failure models for composite materials. Part I (WWFE-I) focused on failure in fiber-reinforced polymer composites under two-dimensional (2D) stresses and ran from 1996 until 2004. Part II was concerned with failure criteria under both 2D and 3D stresses, and ran between 2007 and 2013. Part III, also launched in 2007, was concerned with damage development in multi-directional composite laminates.

Finite Element Libraries: Mixing the “What” with the “How”

Sep 3, 2024

Engineering students first learn statics, then strength of materials, and progress to the theories of plates and shells, continuum mechanics, and so on. As the course material advances from simple to complex, students often think that each theory (model) stands on its own, overlooking the fact that simpler models are special cases of the more complex ones. This view guided the development of the finite element (FE) method in the 1960s and 70s, and ultimately led to legacy FE codes adopting an “element-centric” approach.

The Kuhn Cycle in the Engineering Sciences

Aug 1, 2024

Model development projects are essentially scientific research projects. As such, they are subject to the operation of the Kuhn Cycle, named after Thomas Kuhn, who identified five stages in scientific research projects: Normal Science, Model Drift, Model Crisis, Model Revolution, and Paradigm Change. The Kuhn cycle is a valuable concept for understanding how mathematical models evolve. It highlights the importance of paradigms in shaping model development and the role of paradigm shifts in the process.

Variational Crimes

Jul 8, 2024

From the beginning of FEM acceptance, a significant communication gap existed between the engineering and mathematical communities. Engineers did not understand why mathematicians would worry so much about the number of square-integrable derivatives, and mathematicians did not understand how it is possible that engineers can find useful solutions even when the rules of variational calculus are violated (variational crimes). This gap widened over the years: On one hand, the art of finite element modeling became an integral part of engineering practice. On the other hand, the science of finite element analysis became an established branch of applied mathematics.

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The ESRD Blog

Variational Crimes and Refloating the Costa Concordia

Why Is Solution Verification Necessary?

Chaos in the Brickyard Revisited

Isogeometric Analysis (IGA)

XAI Will Force Clear Thinking About the Nature of Mathematical Models

Meshless Methods

A Critique of the World Wide Failure Exercise

Finite Element Libraries: Mixing the “What” with the “How”

The Kuhn Cycle in the Engineering Sciences

Variational Crimes

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