Confined Compression Mechanical Indentation Rig
Applies controlled axial compressive tare and creep step forces with micro-Newton resolution.
Biomedical Engineering / Cartilage Aggregate Modulus
FREE TO EXPLORELABORATORY 19 · BIOMEDICAL ENGINEERING
Articular Cartilage Confined Compression & Equilibrium Aggregate Modulus
Determine the equilibrium aggregate compressive modulus H_A of articular cartilage under confined compression creep testing using Mow's biphasic biomechanical theory. Explore interactive physiological instrumentation simulation, biomechanics, and biomedical engineering telemetry.
BIOINSTRUMENTATION · BIOSIGNALS · BIOMECHANICS · IMAGING
Your virtual biomedical engineering laboratory.
EQUILIBRIUM COMPRESSIVE STRESS Σ_C—
PHYSIOLOGICAL & TEST CELL TELEMETRY
Ready to sample with Strain ε_c = 0.15 ratio.
Adjust Strain ε_c, then execute biomedical trial.
Biomedical engineering telemetry and physiological states are evaluated rigorously using 64-bit IEEE 754 precision. Residuals reflect ordinary least-squares regression across successive observations. Continuous data structures support high-fidelity biological and physiological modeling.
Biomedical assumptions and boundary condition limits
The linear aggregate modulus model applies to infinitesimal to moderate strains (ε_c ≤ 0.30); higher compressions exhibit strain-dependent stiffening. Evaluated on cylindrical articular cartilage test plugs (diameter 4.0 mm, initial thickness h_0 = 1.50 mm) excised from bovine femoral condyles. Tested in 0.15 M NaCl saline bath at 22 °C under stepwise creep loads until equilibrium strain ε_c is achieved. Linear aggregate slope H_A = 0.6500 MPa across strains 0.05 to 0.30.
Biomedical apparatus & physiological sensors.
Sintered Porous Titanium Platen (pore size 20 μm)
Allows unhindered one-dimensional axial exudation of interstitial fluid while supporting the solid matrix.
Precision Stainless Steel Confined Compression Well
Provides rigid radial boundary confinement preventing lateral cartilage expansion (radial strain ε_r = 0).
Sub-Micron LVDT Displacement Transducer
Measures creep displacement and equilibrium compressive strain ε_c with 0.05 μm resolution.
Temperature-Controlled Physiological Saline Chamber
Maintains 0.15 M NaCl osmotic balance preventing abnormal proteoglycan swelling.
Automated Multi-Hour Data Acquisition System
Records creep transient curves over 3600 seconds per load step until equilibrium is confirmed (dε/dt < 10⁻⁶ s⁻¹).
FOLLOW THE METHOD
A reason behind every step.
Determine the equilibrium aggregate compressive modulus H_A of articular cartilage under confined compression creep testing using Mow's biphasic biomechanical theory. Standardized parameter settings: 0.05, 0.1, 0.15, 0.2, 0.25, 0.3 ratio.
01
Cartilage Plug Harvest and Thickness Metrology
Harvest 4.0 mm diameter full-thickness cartilage plugs from bovine femoral condyles and measure initial uncompressed thickness h_0 using a current-sensing micrometer.
02
Confined Well Placement and Osmotic Equilibration
Place the plug snugly into the precision stainless steel confining well, submerge in 0.15 M physiological saline, and allow 30 minutes for osmotic equilibration.
03
Tare Load and Zero Baseline Contact
Lower the porous titanium platen onto the cartilage surface until a small tare load (0.01 N) is registered, establishing the zero reference displacement position.
04
Stepwise Creep Load Application
Apply a static axial compressive stress step and track continuous vertical displacement as fluid exudes through the porous platen.
05
Equilibrium Creep Criterion Verification
Monitor displacement rate until equilibrium is reached (defined as displacement change < 0.2 μm over 15 minutes, typically requiring 45 to 60 minutes per step).
06
Multi-Step Stress-Strain Regression
Repeat creep equilibration across successive strain levels ε_c = 0.05, 0.10, 0.15, 0.20, 0.25, and 0.30, and determine the equilibrium aggregate modulus H_A.
YOUR NOTEBOOK · 0 OBSERVATIONS
Turn measurements into biomedical engineering insight.
Points are your recorded observations. The solid regression line validates Cartilage Aggregate Modulus mathematical scaling.
LINEAR REGRESSION FIT · y = mx + b
σ_c = H_A · ε_c = 0.6500 · ε_c
| # | Equilibrium Compressive Strain ε_c (ratio) | Equilibrium Compressive Stress σ_c (MPa) | Equilibrium compressive strain ε_c | Equilibrium compressive stress σ_c (MPa) | Remove |
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