Information on the most widely used ASTM standards within the materials testing industry
ASTM F3067, ISO 25539-2
Segmented head stent radial loading compression test fixture is a specialized designed to evaluate the radial mechanical properties of vascular stents, including radial strength, chronic outward force (COF), collapse pressure, and radial stiffness. It simulates the physiological circumferential pressure exerted by blood vessel walls on implanted stents, providing critical data for stent design validation, regulatory compliance, and clinical safety assessment. This device is specifically referenced in ASTM F3067 (Standard Guide for Radial Loading of Balloon Expandable and Self-Expanding Vascular Stents) .
General introduction
Segmented head stent radial loading compression test fixture is a specialized designed to evaluate the radial mechanical properties of vascular stents, including radial strength, chronic outward force (COF), collapse pressure, and radial stiffness. It simulates the physiological circumferential pressure exerted by blood vessel walls on implanted stents, providing critical data for stent design validation, regulatory compliance, and clinical safety assessment. This device is specifically referenced in ASTM F3067 (Standard Guide for Radial Loading of Balloon Expandable and Self-Expanding Vascular Stents) .
Structure: The fixture consists of multiple rigid, segmental wedge blocks (usually 6 to 12) arranged in a circle. These wedges move synchronously along a predetermined arc, either closing inwards or opening outwards
Mechanism: As the wedges move, the effective diameter of the central aperture changes smoothly and concentrically. When a stent is placed inside this aperture, the moving wedges compress (crush) or allow the expansion of the stent in a highly controlled, uniform manner.
Key Features
Uniform Loading: segmented mechanism applies circumferential pressure, eliminating two-point bending artifacts
Physiological Relevance: More accurately simulates vessel wall interaction than flat plate compression
Versatility: Compatible with both balloon-expandable and self-expanding stents of various diameters (2-14 mm)
Precision Control: Microprocessor-controlled movement ensures repeatable test conditions (CV ≤ 5%)
Comprehensive Data: Simultaneous measurement of force, displacement, and diameter changes
ASTM F3067 Standard Guide for Radial Loading of Balloon Expandable and Self-Expanding Vascular Stents.
ISO 25539-2:2020 Cardiovascular implants — Endovascular devices — Part 2: Vascular stents
FDA-1545
FDA Guidance: Non-Clinical Engineering Tests and Recommended Labeling for Intravascular Stents and Associated Delivery Systems – Guidance for Industry and FDA Staff
FDA-1658
FDA Guidance: Coronary and Carotid Embolic Protection Devices – Premarket Notification [510(k)] Submissions
Specification
| Stent Diameter Capacity | 2-14 mm (customizable up to 20 mm) |
| Force Measurement Range | 0-500 N (resolution 0.001 N) |
| Displacement Resolution | 0.001 mm |
| Compression Speed | 0.01-10 mm/min |
| Temperature Control | 37°C ± 0.5°C (range 5-60°C) |
| Segment Count | 6-12 (8 segments standard for optimal balance of uniformity and stiffness) |
| Data Sampling Rate | 100-1000 Hz |
| Test Modes | Static compression, cyclic loading, creep, stress relaxation |
Standard
ASTM F3067 establishes in vitro test frameworks to characterize the radial mechanical performance of balloon-expandable vascular stents and self-expanding vascular stents. It quantifies three key indicators: radial strength and collapse pressure for balloon-expandable stents, and chronic outward force (COF) for self-expanding stents.
ASTM F2606 defines quantitative three-point bending procedures to characterize the bending flexibility and stiffness of balloon-expandable vascular stents and stent systems (pre-deployment and deployed states). It is a critical testing protocol in the biomedical engineering field. Since vascular anatomies are naturally curved and tortuous, a stent must be flexible enough to navigate through the delivery pathway (trackability) and conform to the vessel's curvature once deployed without causing vascular trauma . This standard provides the guidelines to measure these mechanical properties accurately.
ASTM F2942 specifies in vitro test methodologies to evaluate the cyclic durability of vascular stents under non-radial mechanical deformations (axial, bending, and torsion) that occur in vivo due to musculoskeletal motion, breathing, or cardiac activity.
ASTM F2477 designed to evaluate the long-term fatigue durability and radial cyclic deformation resistance of vascular implants under simulated physiological pulsatile loading conditions. It is crucial for simulating the cyclical stresses these medical devices endure inside human blood vessels.
ASTM F2942 specifies in vitro test methodologies to evaluate the cyclic durability of vascular stents under non-radial mechanical deformations (axial, bending, and torsion) that occur in vivo due to musculoskeletal motion, breathing, or cardiac activity. include Axial, bending, torsional, Pulsatile Durability, Radial Loading etc., test.
Step-by-Step Testing Procedure
1, Sample Preparation:
Balloon-expandable stents: Mount on delivery balloon, inflate to nominal pressure, deflate
Self-expanding stents: Load onto delivery system, deploy to nominal diameter
Sterilize and equilibrate in 37°C physiological saline for 10-30 minutes
2, Device Setup:
Install appropriate core shaft (matching stent inner diameter)
Set temperature chamber to 37°C ± 2°C
Calibrate force and displacement sensors
Configure test parameters (speed, compression ratio, cycles)
3, Stent Loading:
Position stent concentrically within the iris segments
Apply preload (0.05-0.1 N) to ensure uniform contact
Verify alignment with optical system
4, Testing Execution:
Start radial compression at specified speed (typically 0.5-2 mm/min)
Record force and displacement data continuously
For cyclic testing: Perform 3-5 preconditioning cycles before data collection
5, Data Analysis:
Generate force vs. diameter curve
Calculate radial strength, COF, stiffness, and hysteresis
Compare results with acceptance criteria from standards and product specifications
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