Structural integrity

This section addresses environmental conditions or the level that the rack mount tested and verified.

Note: The vibration and shock levels given here are the levels that rack mount tested and verified and not the upper limit of what the system can withstand. If you have any environmental conditions higher than specified here, please contact your IBM® representatives.

There are three shock and vibration levels:

Ruggedness (Fragility)
Operational shock and vibration

Ruggedness (Fragility)

Ruggedness relates to a product's ability to withstand the shipping and relocation environments without structural damage. Product ruggedness is assured through shipping shock, vibration, and horizontal impact testing. Passing the test requirements include no short-term and long-term structural and functional degradation. Ruggedness is a key focus item during the new product design phase. Significant analysis and testing efforts are typically associated with new product and subassembly designs to ensure adequate ruggedness for frames, fragile components, and assemblies. To ensure broad protection against shock and vibration, the subassemblies and minimum and maximum system configurations are subjected to unpackaged and packaged testing to cover possible shipping configurations.

Focus on shipping of components in the pod configuration:
- Excessive deflection of chassis during drop test
- Yielding of drawer chassis, frame rails, cages, and subassemblies
- Excessive frame transmissibility
Focus on subassembly level or drawers not installed in a frame include:
- Heatsink retention
- Chip damage due to heatsink loading
- Card interconnect damage
- Card retention and latching
- Card connector fretting wear
- Card and cable connectors
- Power supply assembly fragility
- Cooling components air moving devices

Test levels

There are two vibration test profiles:

Sinusoidal at 0.5 g sweep 2 - 200 Hz for a total of 30 minutes
Random vibration for 15 minutes with power spectral density as shown in Table 1.

For system level testing, the system is subjected to vertical direction vibration.

For subassembly testing, the test is conducted on all three perpendicular axes.

Table 1. Truck, air, rail, and ocean vibration spectrum *
Frequency (Hz)	G²/Hz (PSD level)	graph representation
2	0.0010
4	0.0220
8	0.0220
40	0.0022
55	0.0070
70	0.0070
75	0.0220
200	0.0007
Note: * A rms = 0.8044 G, V rms = 4.508 in/s, D rms = 0.1578 in zero to peak

There are two shock test levels:

System level or the frame with its drawers installed – vertical direction
10 times free fall drops at 39.3 in/s velocity change
2 times free fall drops at 55.6 in/s velocity change
Subassembly or drawers level – in all 6 faces
100 g, 3 ms half sine pulse 2x per face
50 g, 11 ms half sine pulse 2x per face

Since 1980, the shock test levels that are previously specified and vibration test levels specified in Table 1 have been utilized. No documented cases of field problems associated with normal shipping shock and vibration exist.

Operational shock and vibration

Operational shock and vibration relates to a product's ability to withstand normal shock and vibration from its installation environments without functional degradation. Although the shock and vibration sources are typically from the surrounding environment (nearby cooling operating equipment, people walking by or dropping materials, etc.), they also can be self-induced (vibration from fans, blowers, compressors, etc.).

Test levels

All the systems, while running, are verified to meet the vertical vibration level given in Table 2 and Figure 1 without any functional degradation. The rack mount is verified to be able to withstand five vertical shock inputs 3.5 g with 3 ms half sine pulse width.

Table 2. Random vibration PSD profile breakpoint ¹
Class	5 Hz	17 Hz	45 Hz	48 Hz	62 Hz	65 Hz	150 Hz	200 Hz	500 Hz
V1L/V2	2.0x10^-7	2.2x10^-5	2.2x10^-5	2.2x10^-5	2.2x10^-5	2.2x10^-5	2.2x10^-5	2.2x10^-5	2.2x10^-5
Notes: All values in this table are in g²/Hz. For reference only. No test required.

continuous operational vibration — Figure 1. Continuous operational vibration

Documented cases of field problems associated with externally imposed shock and vibration during normal equipment operation are essentially nonexistent.

Quality screen (Manufacturing stress screening)

One application of shock and vibration technology that falls outside the design function is manufacturing stress screening and field failure analysis of intermittent subassemblies, such as the rack mount power supplies. By subjecting samples of production subassemblies to screening tests, it is possible to detect certain manufacturing, component, and design problems in these subassemblies. Typical tests include thermal cycling and random vibration, followed by burn-in and functional test at a vendor or subassembly manufacturer.