What is transmissibility?

Transmissibility is the ratio of the force (or displacement) transmitted to the foundation to the applied force. TR 1 indicates amplification.

How do I design a vibration isolator?

Choose the isolator stiffness so that ω_n is well below the excitation frequency (target r > 2). Soft isolators (low k) give lower ω_n and better isolation but may cause large static deflections.

Why does more damping hurt isolation at high frequencies?

Above r = √2, increased damping increases transmissibility. This is because damping forces are proportional to velocity and transmit energy to the structure at high frequencies.

Force Transmissibility Calculator

Compute TR = √((1+(2ζr)²)/((1−r²)²+(2ζr)²)) where r = ω/ω_n. Isolation is effective when r > √2 (TR < 1). At r = √2, TR = 1 regardless of damping.

2D stress state at a point. All stresses in MPa.

σx — Normal Stress X (MPa)

σy — Normal Stress Y (MPa)

τxy — Shear Stress (MPa)

⚙ Mechanical Note: Results are based on standard textbook formulas and ISO/AASHTO references. Always verify critical designs with applicable codes (ISO 898, AASHTO 1993, AISC, Eurocode 3) and a qualified engineer.

How to Use

Enter the values for the patient or scenario you are assessing. Compute TR = √((1+(2ζr)²)/((1−r²)²+(2ζr)²)) where r = ω/ω_n. Isolation is effective when r > √2 (TR < 1). At r = √2, TR = 1 regardless of damping. Use the transmissibility result to inform your clinical assessment.

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