add wiki

wiki/concepts/_index.md

@@ -6,37 +6,64 @@ tags:
   - meta
   - index
   - concept
-domain: knowledge-management
+domain: computational-mechanics
 status: evergreen
 related:
   - "[[index]]"
   - "[[dashboard]]"
   - "[[Wiki Map]]"
-  - "[[Hot Cache]]"
-  - "[[LLM Wiki Pattern]]"
-  - "[[Compounding Knowledge]]"
-  - "[[LLM Wiki Pattern]]"
-  - "[[Hot Cache]]"
-  - "[[Compounding Knowledge]]"
+  - "[[Computational Mechanics]]"
+  - "[[Finite Element Method]]"
+  - "[[Continuum Mechanics Based Four-Node Shell Element]]"
+  - "[[MITC4 Shell Element]]"
+  - "[[MITC Shell Kinematics]]"
+  - "[[Dynamic Buckling Analysis]]"
+  - "[[Shell Structure Asymptotic Behavior]]"
+  - "[[Isoparametric Linear Solid Elements]]"
 ---
 
 # Concepts Index
 
 Navigation: [[index]] | [[entities/_index|Entities]] | [[sources/_index|Sources]]
 
-All concept pages — ideas, patterns, and frameworks extracted from sources.
+All concept pages: finite-element and computational-mechanics concepts extracted from sources.
 
 ---
 
-## Knowledge Management
+## Computational Mechanics
 
-- [[LLM Wiki Pattern]] — the core architecture for persistent, compounding knowledge bases
-- [[Hot Cache]] — ~500-word session context file, updated after every ingest
-- [[Compounding Knowledge]] — why the wiki grows more valuable over time, unlike RAG
-- [[DragonScale Memory]] — memory-layer spec: fold operator, deterministic page addresses, semantic tiling, boundary-first autoresearch (status: shipped v0.4, all four mechanisms opt-in)
-- [[Persistent Wiki Artifact]]: durable Markdown page as the LLM's memory object (developing)
-- [[Source-First Synthesis]]: provenance discipline for LLM wiki layers (developing)
-- [[Query-Time Retrieval]]: query synthesis with citations, complementary to Obsidian search (developing)
+- [[Finite Element Method]] - numerical procedure for solving discretized engineering and physics models
+- [[Engineering Mathematical Models]] - idealized physical models selected before finite element solution
+- [[Displacement-Based Finite Element Formulation]] - primary solid mechanics formulation using nodal displacements
+- [[Isoparametric Finite Elements]] - shape-function framework for geometry mapping and element matrix calculation
+- [[Isoparametric Linear Solid Elements]] - first-order 3D continuum elements using isoparametric interpolation
+- [[Solid Element Shape Functions]] - interpolation functions for tetrahedral, pyramid, wedge, and hexahedral solid elements
+- [[Solid Element Strain-Displacement Matrix]] - 3D solid element `B` matrix and Jacobian derivative mapping
+- [[Solid Element Stiffness Integration]] - numerical integration of `B^T D B` over element volume
+- [[Incompatible Mode Solid Elements]] - internal-mode enrichment and static condensation for solid elements
+- [[Mixed Finite Element Formulations]] - multi-field formulations for incompressibility, constraints, and pressure-like variables
+- [[Nonlinear Finite Element Analysis]] - incremental solution of geometric, material, contact, and load nonlinearities
+- [[Continuum Mechanics Based Four-Node Shell Element]] - low-order shell element derived from continuum mechanics for nonlinear analysis
+- [[Assumed Transverse Shear Strain Interpolation]] - shell locking remedy using a separately interpolated transverse shear field
+- [[Total Lagrangian Shell Formulation]] - reference-configuration formulation for large displacement and rotation shell response
+- [[MITC4 Shell Element]] - four-node quadrilateral shell element using mixed interpolation of tensorial components
+- [[MITC Shell Kinematics]] - director-vector kinematic model for MITC shell elements
+- [[Green-Lagrange Strain Linearization]] - nonlinear strain expansion for internal force and tangent stiffness terms
+- [[Nonlinear Newmark-Beta Integration]] - implicit Newmark time stepping with Newton-Raphson nonlinear iterations
+- [[Dynamic Buckling Analysis]] - instability analysis of structures under time-varying compressive loading
+- [[Dynamic Instability Region]] - load-frequency instability boundary for parametric buckling
+- [[Geometric Stiffness Matrix]] - initial stress stiffness contribution used in nonlinear and buckling analysis
+- [[Scordelis-Lo Shell Benchmark]] - cylindrical shell benchmark for shell element convergence and locking behavior
+- [[Basic Shell Mathematical Model]] - midsurface/director shell model underlying continuum shell finite elements
+- [[Shell Structure Asymptotic Behavior]] - bending, membrane, and mixed thin-shell response classes
+- [[Shell Locking Phenomenon]] - membrane and shear locking as artificial stiffness in thin-shell FE solutions
+- [[Uniform Optimal Convergence]] - thickness-uniform optimal convergence target for shell elements
+- [[Shell Element Benchmark Testing]] - structured performance testing for shell finite elements
+- [[Finite Element Heat Transfer and Field Problems]] - finite element treatment of heat transfer, field equations, flow, and coupled problems
+- [[Static Equilibrium Equation Solvers]] - direct, iterative, and nonlinear solvers for static FE equations
+- [[Direct Time Integration Methods]] - transient finite element dynamics and first-order field integration
+- [[Finite Element Eigenproblem Solvers]] - modal and eigenvalue algorithms for FE matrices
+- [[Finite Element Program Implementation]] - software data flow for FE codes and STAP-style implementation
 
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