A subway car 81-740.4

Development of engineering solutions aimed at noise level reduction. Designing of sample models for field testing in the upgraded leading car.

Customer

OAO “Metrovagonmash”

Historical background:

81-740/741 “Rusich” is a subway car model mass-produced by the “Metrovagonmash” plant since 2003. As of 2016, coaches of this model made up 33% of the total number of subway cars in Moscow, 64% in Kazan, and 77% in Sofia.

Problem

The noise level inside the driver’s cabin fails to meet the safety requirements of the Sofia Metro.

Tasks

01
To analyze the vibro-acoustic characteristics
02
To search for the weak points in the context of acoustics and to localize the sources and ways of noise penetration.
03
To develop a solution for noise reduction, and to introduce it into the prototype car

Research

We studied the construct of the subway car, held tests and detected the main ways of noise penetration into the driver’s cabin.

Noise penetration channels

Solutions:

We designed a kit of low-combustible parts fitting the requirements of Russian Railways and the EU to railway safety (flammability, toxicity level, lasting properties).

01
To reduce noise level we

transferred the intake grid from the driver’s cabin to the cowl cover and treated the cowl with the sound absorbing material Melaton 2TK.
Materials used
- Melaton 2 TK
  
  Sound absorbing material
  
  More Hide
  
  A foamed material made from melamine resin with 3D open-cell structure. The material is covered with nonflammable water-resistant fabric.
  
  Physical and mechanical characteristics of the material:
  
  Thermal conductivity at a temperature of 25 °С:
  
  0.036W/mK
  
  Flammability class:
  
  Self-extinguishing
  
  Smoke generation ability (Dt=2; Dt=4; Dmax when burning and smoldering)
  
  max: 200
  
  Facing layer-to-foamed layer bond strength:
  
  0.6 N/cm
  
  Anti-adhesive film-to-adhesive layer bond strength:
  
  0.01-0.1 N/cm
02
To reduce noise level we

set the sound absorbing parts of Melaton 2TK in the engineering closet and installed an acoustic panel against the vent hole
Materials used
- Melaton 2 TK
  
  Sound absorbing material
  
  More Hide
  
  A foamed material made from melamine resin with 3D open-cell structure. The material is covered with nonflammable water-resistant fabric.
  
  Physical and mechanical characteristics of the material:
  
  Thermal conductivity at a temperature of 25 °С:
  
  0.036W/mK
  
  Flammability class:
  
  Self-extinguishing
  
  Smoke generation ability (Dt=2; Dt=4; Dmax when burning and smoldering)
  
  max: 200
  
  Facing layer-to-foamed layer bond strength:
  
  0.6 N/cm
  
  Anti-adhesive film-to-adhesive layer bond strength:
  
  0.01-0.1 N/cm
03
To reduce noise level we

filled in the temporary openings in the floor with Melaton 2TK and sealed with VDF.
Materials used
- Melaton 2 TK
  
  Sound absorbing material
  
  More Hide
  
  A foamed material made from melamine resin with 3D open-cell structure. The material is covered with nonflammable water-resistant fabric.
  
  Physical and mechanical characteristics of the material:
  
  Thermal conductivity at a temperature of 25 °С:
  
  0.036W/mK
  
  Flammability class:
  
  Self-extinguishing
  
  Smoke generation ability (Dt=2; Dt=4; Dmax when burning and smoldering)
  
  max: 200
  
  Facing layer-to-foamed layer bond strength:
  
  0.6 N/cm
  
  Anti-adhesive film-to-adhesive layer bond strength:
  
  0.01-0.1 N/cm
- VDF
  
  Vibration absorbing material
  
  More Hide
  
  Multilayer material consisting of embossed aluminium foil and an adhesive polymer layer covered with anti-adhesive paper
  
  Physical and mechanical characteristics of the material:
  
  Flammability class:
  
  Combustible Hardly inflammable
  
  Sealant-to-painted metal surface bond strength whilst peeling off:
  
  3.0 N/cm
  
  Resistance to low temperatures (-60 °С):
  
  the material doesn’t peel off from the painted metal plate
  
  Smoke generation coefficient:
  
  moderate smoke generation ability
04
For soundproofing we

mounted an extra metal sheet on the floor and added filling pieces of the Stp Fp between the corrugated plate and plywood sheet.
Materials used
- STP FP
  
  Sealant
  
  More Hide
  
  An adhesive polymer layer covered with anti-adhesive paper on both sides.
  
  Physical and mechanical characteristics of the material:
  
  Flammability class:
  
  Hardly inflammable
  
  Sealant-to-painted metal surface bond strength whilst peeling off:
  
  3.0 N/cm
  
  Resistance to low temperatures (-60 °С):
  
  the sealant doesn’t peel off from the painted metal plate
  
  Smoke generation coefficient:
  
  500 m²/kg
05
For soundproofing we

replaced the double-glazing unit in the door with the one with the better sound insulation
06
To eliminate tinkling we

treated the closet door with the vibration damping material VDF-1.8.
Materials used
- VDF
  
  Vibration absorbing material
  
  More Hide
  
  Multilayer material consisting of embossed aluminium foil and an adhesive polymer layer covered with anti-adhesive paper
  
  Physical and mechanical characteristics of the material:
  
  Flammability class:
  
  Combustible Hardly inflammable
  
  Sealant-to-painted metal surface bond strength whilst peeling off:
  
  3.0 N/cm
  
  Resistance to low temperatures (-60 °С):
  
  the material doesn’t peel off from the painted metal plate
  
  Smoke generation coefficient:
  
  moderate smoke generation ability