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Tag Archive: isolators

  1. Protecting Electronic Devices from Vibration & Shock

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    Vibration is bad for electronics. It can damage the boards and components potentially causing permanent failure. But a well-engineered enclosure protects delicate equipment from vibration damage by isolating it from external sources. Utilizing a stabilizer kit for your rack can add an additional layer of security.

    These vital electronics are subjected to stressors in a wide spectrum of applications ranging from in-office or industrial power stations to ruggedized, aerospace systems or other military deployment. Even if intended for more mild environments, nearly all electronics are subject to some level of vibration during their lifecycle. Typical shock values for industrial use might be in the 5G to 10G range whereas systems on naval ships need to withstand shocks in excess of 20G.

    Types of shock and vibration

    If your equipment is mounted on a ground-based or airborne vehicle, shipboard mounted or needs to withstand natural weather patterns and seismic events, ruggedized construction should be one of the, if not THE, primary design criteria.

    There are two types of vibration: random or sinusoidal. Random is a varying waveform similar to riding in a vehicle rolling across rough terrain. Sinusoidal vibration occurs at distinct frequencies and is continuous, like that of a rotating engine on a helicopter.

    Stress testing can uncover defects in a design before they become expensive problems. And often times, the only way to verify that a rack and its isolation mounts will provide sufficient protection is through instrumented testing. Our A&J electronic equipment racks have been designed and tested to meet MIL standards:

    • MIL-STD 810F — environmental shock and vibration
    • MIL-STD-167 — shipboard vibration
    • MIL-STD-901D — high impact and shock testing for Navy shipboard machinery and equipment

    Rack Type

    Test

    Rack Height (in)

    Model

    Test Results

    Light Duty

    Shock

    72

    9264-1000-1

    MIL-S-901C
    Total weight 1211 lbs.
    Hard mounted

    Light Duty

    Shock and Vibration

    72

    9096-109

    MIL-S-901C Blows
    Total weight 845 lbs.
    Hard mounted

    Medium Duty

    Shock and Vibration

    76

    9260-1000

    MIL-STD-810, method 516
    Isolation system installed
    Vibration to 33 Hz

    Medium Duty

    Shock

    72 H, 30 D

    9399-1000

    MIL-S-901C
    Total weight 638 lbs.
    Vibration to 33 Hz

    Medium Duty

    Shock

    60

    60-D1-1001

    MIL-S-901C 9
    Total weight 1254 lbs.
    Hard mounted

    Medium Duty

    Shock and Vibration

    68.68

    9216-1000

    MIL-S-901C 9 Blows
    Total weight 1254 lbs.
    Isolation system installed

    Medium Duty

    Shock and Vibration

    72

    9194-100

    MIL-S-901C 12 Blows
    Total weight 998 lbs.
    Hard mounted
    Vibration to 33 Hz

    Medium Duty

    Shock and Vibration

    59

    9153-1000

    MIL-S-901C 9 Blows
    Total weight 865 lbs.
    Hard mounted
    Simulated weight

    Medium Duty

    Shock and vibration

    72

    72-D1-1001

    MIL-S-901C 9 Blows
    Two racks joined at the top
    Total weight 1262 lbs.
    Hard mounted

    Medium Duty

    Shock and vibration

    40

    9149-100

    MIL-S-901C 6 Blows
    Total weight 450 lbs.
    High temp & humidity

    Medium Duty

    Shock and vibration

    72 H, 36 D, 36 W

    9423-1001

    MIL-S-901C 9 Blows
    Total weight 695 lbs.
    Internal isolation systems

    Medium Duty

    Shock

    60

    60-D1-1001

    MIL-S-901C 9 Blows
    Total weight 650 lbs.
    Hard mounted

    Heavy Duty

    Shock and Vibration

    76

    76-G1-1001

    MIL-S-901C Blows
    Total weight 922 lbs.
    Free standing

    Heavy Duty

    Shock and vibration

    72

    9143-100 TG-2

    MIL-S-901C 9 Blows
    Total weight 928 lbs.
    Hard mounted
    Simulated weight

    Key rack components to protect against shock & vibration

    Isolators

    The main goal in handling shock and vibration is to isolate the equipment from excitement by reducing the amplitude and frequency of waves. Enter: isolators. They’re critical! And act as a highly stable buffer between the source of the vibration and the object or surface. A good system has two main components, a spring to support the load and a damping element to dissipate the energy.

    Two common types of vibration isolators are used in rack configurations: 

    • Wire Rope Coils – the ideal solution for providing low frequency, highly damped vibration isolation and excellent shock attenuation. They often require little maintenance, are made from durable metals and keep functioning under varying temperatures in corrosive environments. 
    • Seismic Mounts – whether you’re in a seismic region of the country or on a Naval ship, these mounts are designed to provide the strength and isolation necessary to control the motion of equipment

    Varying the size, shape, construction material and number of coils all affect the spring rate and damping, as well as mounting placement. 

    Common applications for vibration and shock isolators include avionics and equipment, computer equipment and disc drivers, control panels, electrical transformers, fans and blowers, industrial machinery, marine and shipboard equipment, medical equipment, power plants and cooling towers, pumps and centrifuges, and compressors. 

    Rack Frame

    Obviously the rack’s exterior frame should be rigid construction to withstand any buckling. At A&J, we developed a unique bolted-together design that lends structural integrity, eliminating the need for welding. The modular design allows a wide range of sizes and configurations to be incorporated. For seismic zones or rugged applications, a back stiffener or X-brace can be added near the top, middle and bottom to protect from movement. Another option to consider is double-walled construction where the frame has two layers of sheet metal for extra strength. 

     Contact us for more detail on a particular enclosure design feature or schedule a chat with one of our engineers

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