What is the calculation formula for electrodynamic shaker thrust?

The calculation formula is F = m_total * a * Safety Factor. Where m_total represents the cumulative mass of the test specimen, structural fixtures, slip tables/head expanders, and the internal copper armature coil; 'a' stands for the target test acceleration; the safety factor is ideally set between 1.2 and 1.3.

Why do larger head expanders degrade high-frequency shaker capacity?

According to the ISO 5344 standard, the upper operating frequency is bounded by the system's first major axial resonance frequency. Oversized expander tables add massive amounts of load while lowering cross-axis stiffness, driving this resonance point downwards and causing high-frequency signal distortion.

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High-Frequency Vibration Shaker Selection ASLI Engineer's Practical Guide

July. 02, 2026

ASLI™ Testing

High-Frequency Shaker Guide

How to Select a High-Frequency Vibration Shaker?
ASLI Engineering Handbook

From specimen dimensions to thrust calculations, armature materials to high-frequency traps—this practical handbook helps you match the perfect shaker system to your exact testing profile.

Specimen-Driven Setup Force = Mass × Acceleration Al vs. Mg Slip Tables Frequency Cutoff Factors

The Selection Logic Chain

Vibration shaker sizing is not an isolated decision; it is an interdependent calculation chain where every link impacts the next:

Specimen Size → Table Dimensions → Total Moving Mass → Required Force → Model Verification

Core Concept: Manufacturer ratings (including ASLI's) for rated thrust exclude the mass of the payload and custom fixtures. Always budget a 20% to 30% force safety margin. Neglecting this means the system will fail to reach target acceleration once real-world expanders are bolted on.

Step 1: Size the Table to the Specimen

The footprint of your test object dictates the minimum size of the table. A standard aerospace/automotive rule of thumb is:

Table Surface Area ≥ Specimen Footprint × 1.3 to 1.5

This ensures the specimen does not overhang the table edges, which would introduce structural flexing and cause edge-to-center amplitude deviations exceeding ±3%.

The Headboard Tax: Adding large vertical expanders or slip tables increases moving mass significantly and lowers the upper frequency limit. For example, an ASLI bare armature rated up to 2500Hz may see its practical limit drop to 1500Hz once fitted with a wide expander.

Material Properties: Aluminum vs. Magnesium

Material	Density	Specific Stiffness	Cost Profile	ASLI Recommended Use Case
Aluminum 6061-T6	≈2.7 g/cm³	Good	Cost-Effective	Standard industrial profiles; general purpose testing.
Magnesium Alloys	≈1.8 g/cm³	Excellent	Premium	High-frequency profiles; large head expanders where weight reduction is mandatory.

ASLI Selection Standard: Aluminum is perfectly adequate for 80% of testing setups. Upgrade to magnesium only if target accelerations are heavily force-limited or large expanses must be structurally light. Magnesium saves ~35% weight but carries a 40%–60% cost premium.

Step 2: Calculate Required Force (Thrust)

The foundational calculation uses Newton's Second Law, adjusted for environmental testing environments:

F = m_total × a × Safety Factor

m_total = Specimen Mass + Fixture Mass + Table/Expander Mass + Armature Mass (from ASLI datasheet)
a = Target Acceleration (in g or m/s²)
Safety Factor = 1.2 to 1.3 (ASLI highly recommends 1.3 for high-frequency profiles)

???? Practical Calculation Example: 50kg Battery Module at 10g

Total Moving Mass = 50kg (Specimen) + 15kg (Fixture) + 25kg (ASLI Expander) + 12kg (Armature) = 102 kg

F = 102 kg × 10g × 1.3 = 1326 kgf (~13 kN)

→ Recommended selection: An ASLI system rated at ≥ 1400 kgf (14 kN) force.

Common Error: Many operators multiply just the specimen weight by the target acceleration. This undercalculates the demand by 30% to 50% because it treats fixtures and the copper armature coil as weightless. ASLI provides complimentary calculations to clear up these discrepancies.

Step 3: Map the Performance Curve

Every ASLI electrodynamic shaker is bound by a Performance Curve divided into three discrete physical regions:

Region	Frequency Range	Limiting Physical Factor
Low Freq	Typically below 50Hz	Displacement (Peak-to-Peak Stroke limit)
Mid Freq	Approx. 50 to 300Hz	Velocity (Power amplifier voltage cap)
High Freq	Above 300Hz	Force/Acceleration (Armature current/mass limits)

Note: Performance curves are mapped under **"Bare Armature"** conditions. Adding loads shifts these envelopes downward.

ASLI Best Practice: Request a loaded performance curve from your ASLI application engineer to ensure your profile stays well within the safe operational envelope.

The High-Frequency Trap: Table Expansion vs. Response

Per ISO 5344, the **maximum usable high-frequency limit** of a shaker system is constrained by its first major axial resonance frequency. Bulky, wide expansion tables shift this resonance point directly into lower frequencies.

The Golden Rule: The broader the table surface, the lower your maximum reliable test frequency.

If your test profile calls for 2000Hz, but an oversized expander drops the system's combined resonance point down to 1200Hz, any data collected at 2000Hz will be unusable due to massive cross-axis distortion and phase delays.

ASLI Mitigation Strategy: If your footprint demands a large table but your profile requires high frequencies, you must scale up the shaker's base force capacity (e.g., ASLI E-Series). The stiffer, heavier suspension system pushes the resonance frequencies back up into a safe testing range.

ASLI 7-Step Sizing Matrix

Log physical dimensions & weight of the largest intended test article.
Define testing profiles (g level, frequency band, random/sine profiles, standards like MIL-STD or ISO).
Sum total moving mass (Specimen + custom fixture designs + expander head + armature).
Run the force equation using a 1.3 margin multiplier.
Select structural material: Aluminum for standard setups, Magnesium for critical high-frequency projects.
Plot against ASLI Performance Curves to secure velocity and stroke clearance.
Verify resonance frequencies to guarantee cross-axis metrics remain clean at your highest testing octaves.

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