Dynamic fracture strength tester

Dynamic fracture strength tester

Implantable drug delivery deviceDynamic fracture strength testerIt is a specialized device used to evaluate the structural strength and durability of implantable drug release devices (such as implantable pumps, drug-eluting stents, subcutaneous implants, etc.) under dynamic mechanical loads. Its core function is to simulate the periodic external forces that the device may experience in the human body (such as muscle contraction, joint movement, blood flow impact, etc.), detect whether the device will break or fail under long-term dynamic stress, and ensure its clinical safety.

Key components and working principles

1. Mechanical loading system

• Driven by hydraulic, pneumatic or electric servo motors, dynamic tensile, compressive, bending or torsional loads can be applied.

• Dynamic parameter controlAdjustable loading frequency (such as 0.1-50 Hz), amplitude, waveform (sine wave, square wave, etc.), and number of cycles to simulate the mechanical environment of different physiological activities.

2. Environmental simulation module

• temperature controlSimulate human body temperature (37 ± 0.5 ℃), and some devices integrate liquid tanks to simulate body fluid environments (such as PBS solution).

• Multi axis motion couplingSome devices support multi degree of freedom composite movements (such as stretching and twisting), which are closer to real physiological conditions.

3. Sensors and Data Collection

• High precision force sensorReal time monitoring of dynamic loads (typically ranging from 0-500 N, resolution ≤ 0.1 N).

• Displacement/strain sensorRecord device deformation, crack propagation rate, and fracture point.

• Data synchronization analysisThe software automatically draws stress-strain curves, calculates fatigue limit, fracture strength, and cycle life.

4. Sample fixture

• Customized fixture design to adapt to different implant device forms (such as tubular stents, thin film drug capsules, micro pump bodies, etc.), ensuring uniform transmission of loading force and avoiding local stress concentration.

Testing methods and standards

1. Typical testing process

• preloadInitial static loading to nominal load, eliminating assembly gaps.

• Dynamic fatigue testingApply cyclic load at a set frequency and amplitude until the preset number of cycles (such as 10 ^ 6 times) or until fracture occurs.

• Failure AnalysisRecord the fracture location and number of cycles, analyze the fracture morphology using microscopic imaging (SEM or optical microscope), and determine the failure mode (brittle/ductile fracture).

2. reference standard

• ISO 14602Testing the anti dynamic fatigue performance of non active surgical implants.

• ASTM F2076Dynamic fatigue assessment method for spinal implants (some provisions apply).

• YY/T 0662Guidelines for fatigue testing of cardiovascular implants (expandable to other implantable drug delivery devices).

Application scenarios

1. Drug-eluting stentTest the anti fatigue performance of the stent during vascular pulsation to prevent drug burst release caused by coating rupture or metal fatigue.

2. Implantable infusion pumpEvaluate the sealing and structural integrity of the pump casing and tubing under long-term muscle activity.

3. Sustained-release subcutaneous implantSimulate the bending/twisting effects of daily activities on implants to ensure that there is no risk of leakage in drug delivery systems.

4. Targeted drug delivery microneedle arrayDetecting the fracture threshold of microneedles under dynamic loads and optimizing material and geometric design.

重要性

• Security verificationTo prevent the risk of excessive drug release, local tissue damage, or secondary surgical removal due to device breakage.

• life predictionCalculate the reliability of implanted devices in vivo for several years through accelerated fatigue testing.

• R&D optimizationGuide material selection (such as titanium alloys, medical polymers) and structural design (such as reinforcing ribs, stress dispersing holes).

Example parameters (for a certain commercial model)

Through such testers, manufacturers can systematically evaluate the dynamic mechanical performance of implantable drug delivery devices, providing critical data support for preclinical validation and regulatory approval.