IEC 60068-2-55-2013 pdf download

IEC 60068-2-55-2013 pdf download.Environmental testing – Part 2-55: Tests- Test Ee and guidance – Loose cargo testing including bounce.
4 Requirements for the test apparatus
4.1 General test description
The specimen is installed on a vibrating platform without a fixture and occasionally bounces, according to the mass and stiffness of the platform and the specimen, and the prescribed motion. No direct control is imposed on the specimen motion. Wherever possible, the test severity applied to the specimen shall be related to the operational environment to which the specimen will be subjected during transportation.
The re’evant specification shall state the criteria upon which the acceptance or rejection of the specimen is to be based. Normally, for this test the specimen is not functioning and it is sufficient that it should survive the testing.
4.2 Characteristics of the testing machine
The testing machine shall consist of a horizontal platform coupled to a shaker or a similar drive mechanism, If prescribed by the relevant specification, special bounce testing machines may be used (see Clause A.3).
The platform shall be of at least 24 mm and not to exceed 32 mm plywood firmly attached to a suitable stiff frame, if required. with appropriate barriers (see 4.7). It shall be of sufficient size to support the specimen. Furthermore, the characteristics of the testing machine shall allow for the prescribed motion of the platform, see 4.3.
4.3 Motion of the platform
The motion of the platform shall be vertical linear, also when loaded by the specimen and any other devices necessary for conducting the test. A rotary motion of the platform is not possible when connected to a shaker table. The relevant specification can prescribe sinusoidal or random vibration of the platform.
The deflections of the platform resulting from the bouncing specimen shall be negligible. This can be achieved by sufficient strength and stiffness of the supporting stiff frame.
If prescribed by the relevant specification, other kinds of motion can be used that require special bounce testing machines, such as circulating (see A.3.1) or non-synchronous (A.3.2) motion of the platform.
4.4 Tolerances on the horizontal accuracy of platform
The testing machine shall be installed so that at its lowest point (bottom dead centre of the motion), the platform is horizontal within the following tolerance:
— ±0,5° in the longitudinal and lateral axes (respectively pitching and rolling angles). Any allowances for play of the drive mechanism are included in this value.
4.5 Control
The motion of the platform is controlled. Acceleration or disp’acement contro’ is permissible. If the platform is driven mechanically by eccentrics, actual eccentricity and control of the shaft speed may be used. It is not necessary to measure the response of the specimen.
The impacts of the specimen on the platform are very likely to influence the actual motion of the platform. The occurrence of high-frequency oscillations resulting from these impacts shall be considered, as this may lead to signal distortion without appropriate filtering. In the case of the reference point being influenced by the impacting, and the stated tolerances not being able to be met, the achieved result shall be stated in the test report.
4.6 Mounting
For the purpose of this test, the specimen is never fastened or otherwise fixed to the platform during testing.
4.7 Horizontal motion of specimen
The horizontal motion of the specimen shall be limited by suitable barriers of sufficient strength and stiffness.
The maximum horizontal clearance shall be small compared to the size of the specimen but large enough to allow for free vertical movement. Normally, this is achieved by a clearance of approximately 10 mm on each side.
A suitable barrier arrangement is described in Clause A.2 and shown in Figure A.1.
5 Seventies
NOTE Severity is described by the motion of the platfom and the testing duration.
5.1 Severity for sinusoidal motion of the platform
If sinusoidal vibration is required, the relevant specification should refer to IEC 60068-2-6 and prescribe the amplitude and frequency of the motion together with the testing duration.IEC 60068-2-55 pdf download.