Concept Architecture
Concept
Theoretically, the Finite Element Method (FEM) is a numerical technique for obtaining approximate solutions to partial differential equations by dividing a continuous domain into a finite number of interconnected elements. Within each element, the unknown solution is approximated using interpolation functions, and the individual element equations are assembled into a global system representing the entire domain. The method is founded on variational principles and weighted residual methods and is widely used to solve complex boundary value problems in engineering, physics and biomedical sciences. In health economics, finite element methods may be used indirectly within physiological, biomechanical or pharmacological models that generate evidence for economic evaluation.
Mathematically, the Finite Element Method transforms a continuous differential equation into a finite-dimensional system of algebraic equations. The solution is approximated as a weighted sum of basis functions defined over each element, and the coefficients are obtained by solving the assembled global matrix equation. Numerical accuracy depends on the element type, mesh density, interpolation order and convergence properties of the discretised system.
In practice, finite element methods are implemented using specialised numerical software rather than spreadsheet calculations. Applications relevant to health economics include biomechanical modelling of medical devices, physiological simulations, tissue mechanics, drug transport modelling and other computational models that inform estimates of clinical effectiveness, resource utilisation or long-term health outcomes incorporated into decision-analytic models.
Purpose
Used to obtain numerical solutions to complex partial differential equations over irregular geometries by discretising a continuous domain into finite elements, supporting advanced computational models that contribute evidence for health economic evaluation.
Mathematical Formulae
Primary Formula
Global finite element system:
Kx = f
where K is the global stiffness matrix, x is the vector of unknown nodal values and f is the load or forcing vector.
Supporting Formulae
Approximate solution:
u(x) � ?N?(x)a?
Element matrix:
K? = ?B?DB d�
Global assembly:
K = ?K?
Related Mathematical Methods
- Finite Difference Method
- Boundary Element Method
- Galerkin Method
- Weighted Residual Method
- Numerical Integration
- Partial Differential Equation
- Matrix Algebra
Example
A biomechanical model evaluates stress distribution within a hip implant to estimate implant longevity. The implant geometry is divided into thousands of finite elements, producing the global system Kx = f. The predicted mechanical performance contributes evidence regarding revision rates, which are subsequently incorporated into a lifetime cost-effectiveness model comparing alternative prostheses.
Excel Implementation
| Function | Example Formula | Health Economics Application |
|---|---|---|
| MMULT | =MMULT(K_range,x_range) | Performs matrix multiplication for finite element calculations. |
| MINVERSE | =MINVERSE(K_range) | Computes the inverse of a coefficient matrix for small demonstration problems. |
| LET | =LET(K,Matrix1,F,Vector1,MMULT(MINVERSE(K),F)) | Improves readability of matrix-based calculations. |
| TRANSPOSE | =TRANSPOSE(MatrixRange) | Supports matrix operations during finite element analysis. |
| SUMPRODUCT | =SUMPRODUCT(Array1,Array2) | Computes weighted sums within numerical approximations. |
VBA (Optional)
VBA can automate matrix assembly, iterative solution procedures and post-processing for small educational finite element models implemented in Excel.
Sources
- Zienkiewicz OC, Taylor RL, Zhu JZ. The Finite Element Method: Its Basis and Fundamentals. Elsevier.
- Hughes TJR. The Finite Element Method: Linear Static and Dynamic Finite Element Analysis. Dover Publications.
- Bathe KJ. Finite Element Procedures. Prentice Hall.
- Briggs A, Claxton K, Sculpher M. Decision Modelling for Health Economic Evaluation. Oxford University Press.
- Drummond MF, Sculpher MJ, Claxton K, Stoddart GL, Torrance GW. Methods for the Economic Evaluation of Health Care Programmes. Oxford University Press.
Related Concepts (4)
Library
Publications
1
Numerical Analysis of Parameterized Nonlinear Equations — Werner C. Rheinboldt, 1st Edition ed., 1986 (John Wiley & Sons)
A specialist numerical-analysis reference on iterative solution, continuation and computation for parameterized nonlinear systems, linked here to the ontology's numerical-method and optimization branch.
BookView source →
Frequently Asked Questions (6)
What is the finite element method?
A numerical method that divides a complex domain into smaller elements to approximate the solution of differential equations.
Source: Strang G, Fix GJ. An Analysis of the Finite Element Method. Prentice-Hall; 1973.
How does the finite element method approximate a solution?
The finite element method approximates the solution of differential equations by dividing a complex domain into smaller elements and building an approximate solution piece by piece across them. Each element carries a simple local approximation, and these are assembled into a solution over the whole domain. This division of a complicated region into manageable elements is how the finite element method handles problems that would be hard to solve directly By covering an awkward region with a mesh of simple elements and stitching their local solutions together, the method handles geometries that a single global approximation could not manage.
Source: Strang G, Fix GJ. An Analysis of the Finite Element Method. Prentice-Hall; 1973.
Why does the finite element method divide the domain into elements?
The finite element method divides the domain into smaller elements because a complex region is difficult to treat as a whole, whereas each small element admits a simple local approximation. Breaking the domain down lets the method approximate the solution of differential equations across shapes that vary from place to place. This subdivision into elements is the defining step that gives the finite element method its flexibility with complex domains By covering an awkward region with a mesh of simple elements and stitching their local solutions together, the method handles geometries that a single global approximation could not manage.
Source: Strang G, Fix GJ. An Analysis of the Finite Element Method. Prentice-Hall; 1973.
What kind of domain suits the finite element method?
A complex domain suits the finite element method, since it is designed to divide such a domain into smaller elements to approximate the solution of differential equations. Irregular or complicated regions that resist a single global treatment can be covered by a mesh of elements. This ability to handle complex domains by subdivision is a central reason the finite element method is used By covering an awkward region with a mesh of simple elements and stitching their local solutions together, the method handles geometries that a single global approximation could not manage.
Source: Strang G, Fix GJ. An Analysis of the Finite Element Method. Prentice-Hall; 1973.
What does the finite element method produce across the elements?
The finite element method produces an approximate solution of the differential equations across the elements, assembling local approximations on each small element into a solution over the whole domain. Because the domain has been divided into elements, the method builds the overall answer from these pieces. This piecewise construction over the elements is what the finite element method yields By covering an awkward region with a mesh of simple elements and stitching their local solutions together, the method handles geometries that a single global approximation could not manage.
Source: Strang G, Fix GJ. An Analysis of the Finite Element Method. Prentice-Hall; 1973.
How does the finite element method relate to the finite difference method?
The finite element method divides a complex domain into smaller elements to approximate the solution of differential equations, while the finite difference method approximates derivatives using finite differences to solve them. Both solve differential equations numerically but discretise differently, the finite element method by subdividing the domain and the finite difference method by replacing derivatives. The two are connected as alternative numerical approaches to the same kind of problem By covering an awkward region with a mesh of simple elements and stitching their local solutions together, the method handles geometries that a single global approximation could not manage.
Source: Strang G, Fix GJ. An Analysis of the Finite Element Method. Prentice-Hall; 1973.
Trust Record
Verified by Dr Darrin Baines
British health economist
Professional identity: darrinbaines.org
Verification date: 2 Apr 2026
Content version: 1.0.0
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