1.0.1 This Code is formulated with a view to properly selecting relevant dynamic parameters, supporting structure types and isolators for vibration isolation design according to the characteristics of vibration source and vibration isolated object, achieving advanced technology, economic rationality, ensuring regular production and meeting the environmental requirement.
1.0.2 This Code is applicable to design of vibration isolation under the following conditions:
1 Active vibro-isolation of dynamic machine which generates harmful vibration effect to the surrounding environment of production, work and buildings.
2 Passive vibro-isolation of instrument, meter or machine which sensitive to surrounding environment vibration or cannot be used normally when suffering environmental vibration.
1.0.3 This Code is not applicable to isolating the vibration caused by earthquake, wind vibration, wave and noise as well as the vibration isolation of antique buildings.
1.0.4 The design of vibration isolation shall meet not only the requirements stipulated in this Code, but also the provisions of the related current national standards.
2 Terms and Symbols
2.1 Terms
2.1.1 Active vibro-isolation
Vibration isolating measures taken to reduce the vibration caused by dynamic machine.
2.1.2 Passive vibro-isolation
Vibration isolating measures taken to reduce the outside vibration effect on instrument, meter or machine which are sensitive to vibration.
2.1.3 Vibration isolating system
The system composed by vibration isolated object, pedestal structure, isolator and damper.
2.1.4 Vibration isolated object
Machine, instrument or meter which shall be isolated from vibration.
2.1.5 Allowable vibration value
The maximum vibration limit at the required point or surface.
2.1.6 Transmissibility
For active vibro-isolation, it refers to the ratio of output vibrational line displacement and static displacement of vibration isolating system under disturbing force;
For passive vibro-isolation, it refers to the ratio of output vibrational line displacement and the externally disturbed vibrational line displacement of vibration isolating system;
For ground barrier isolation, it refers to the ratio of ground vibrational line displacement before and after the setting of barrier.
2.1.7 Isolator
Bearing component which is able to damp vibration.
2.1.8 Damper
The device reducing vibration amplitude by energy loss.
2.2 Symbols
2.2.1 Action and action effect
Pox - disturbing force acting on the mass center of vibration isolating system and along the X axis direction;
Poy - disturbing force acting on the mass center of vibration isolating system and along the Y axis direction;
Poz - disturbing force acting on the mass center of vibration isolating system and along the Z axis direction;
Mox - disturbing moment acting on the mass center of vibration isolating system and rotating around X axis;
Moy - disturbing moment acting on the mass center of vibration isolating system and rotating around Y axis;
Moz - disturbing moment acting on the mass center of vibration isolating system and rotating around Z axis;
A - displacement of disturbing vibrational line;
Ax - vibrational line displacement at the mass center of vibration isolating system and along the X axis direction;
Ay - vibrational line displacement at the mass center of vibration isolating system and along the Y axis direction;
Az - vibrational line displacement at the mass center of vibration isolating system and along the Z axis direction;
- vibration angle displacement at the mass center of vibration isolating system and rotating around the X axis direction;
- vibration angle displacement at the mass center of vibration isolating system and rotating around the Y axis direction;
- vibration angle displacement at the mass center of vibration isolating system and rotating around the Z axis direction;
Aox - displacement of disturbing vibrational line generated at supporting structure or foundation and along the X axis direction;
Aoy - displacement of disturbing vibrational line generated at supporting structure or foundation and along the Y axis direction;
Aoz - displacement of disturbing vibrational line generated at supporting structure or foundation and along the Z axis direction;
- displacement of disturbing vibration angle generated at supporting structure or foundation and rotating around the X axis direction;
- displacement of disturbing vibration angle generated at supporting structure or foundation and rotating around the Y axis direction;
- displacement of disturbing vibration angle generated at supporting structure or foundation and rotating around the Z axis direction.
2.2.2 Calculation indexes
Kx - total rigidity of the isolator along X axis direction;
Ky - total rigidity of the isolator along Y axis direction;
Kz - total rigidity of the isolator along Z axis direction;
- total rigidity of the isolator rotating around X axis;
- total rigidity of the isolator rotating around Y axis;
- total rigidity of the isolator rotating around Z axis;
ω - disturbance circular frequency;
ωnx - undamped natural circular frequency of vibration isolating system along X axis direction;
ωny - undamped natural circular frequency of vibration isolating system along Y axis direction;
ωnz - undamped natural circular frequency of vibration isolating system along Z axis direction;
- undamped natural circular frequency of vibration isolating system rotating around X axis;
- undamped natural circular frequency of vibration isolating system rotating around Y axis;
- undamped natural circular frequency of vibration isolating system rotating around Z axis;
ωnl - undamped natural circular frequency of the first vibration mode under two-degrees-of-freedom coupled vibration;
ωn2 - undamped natural circular frequency of the second vibration mode under two-degrees-of-freedom coupled vibration;
x - damping ratio when the isolator is vibrating along X axis direction;
y - damping ratio when the isolator is vibrating along Y axis direction;
z - damping ratio when the isolator is vibrating along Z axis direction;
- damping ratio when the isolator is vibrating around X axis;
- damping ratio when the isolator is vibrating around Y axis;
- damping ratio when the isolator is vibrating around Z axis;
Est - static elastic modulus of vibration isolation materials;
Ed - dynamic elastic modulus of vibration isolation materials;
[A] - allowable vibrational line displacement;
[V] - allowable vibration velocity;
[τ] - allowable shear stress;
m - total mass of vibration isolating system.
2.2.3 Geometric parameters
z - vertical distance from the rigidity center of isolator or hanger rod lower end to the mass center of vibration isolating system;
Jx - rotational inertia of vibration isolating system around X axis;
Jy - rotational inertia of vibration isolating system around Y axis;
Jz - rotational inertia of vibration isolating system around Z axis.
3 Basic Requirements
3.1 Design Conditions and Vibration Isolation Method
3.1.1 The following data shall be provided for the design of vibration isolation:
1 Type, specification and overall dimension of vibration isolated objects.
2 Mass center position, quality and rotational inertia of vibration isolated objects.
3 Outline drawing of vibration isolated object base, position of auxiliary facilities and pipelines, size of pits, trenches and holes, thickness of grouting layer and the position of anchor bolts and embedded parts.
4 Piping plan related to the connection of vibration isolated object and foundation.
5 Where the isolator is supported on the floor-slab or holder, the design data of supporting structure shall be provided. Where the isolator is supported on the foundation, relevant data such as engineering investigation, subgrade dynamic parameter and adjacent foundation shall be provided.
