Committee of experts on the transport of dangerous goods and on the globally harmonized system of classification
Download 284.47 Kb.
|
Proposal 112. COSTHA proposes the Working Group consider the following changes to the T.4 test: 13. COSTHA recommends revising the conditions of the T4 test to address the significant amplification of force in testing large format batteries. Instead of setting the acceleration (gn) as a constant (150 gn for <12 kg batteries and 50 gn for >12 kg batteries), we recommend that the shock acceleration be scaled for larger batteries. One concept would hold force constant from 50gn /12kg. COSTHA proposes that the peak acceleration be varied based on the mass of the battery and the force of the 12kg, 50 gn shock profile per the formula below: Peak Acceleration (gn) = 
14. To offset the change in peak acceleration for the mass correction noted in 13 above, the pulse duration should be adjusted such that the total energy expended during the shock pulse is equivalent to the energy of the 12kg, 50 gn shock. The following formula approximates the energy for the 50 gn pulse at 12.0 kg. Energy = 
Change in Velocity for Acceleration Pulse = 
For 50 gn, 12 kg:  = 70.8 Joules
When the peak amplitude is changed the pulse duration must be adjusted to maintain the total energy of the pulse. The pulse duration is based on the 50 gn, 12 kg shock profile and calculated per the formula below: 
For example, a 15 kg battery would require a 40 gn shock. The acceleration pulse duration necessary to maintain the 50 gn, 12 kg shock energy is:  = 12.3 mSec
15. Testing labs have requested to constrain the pulse duration to a maximum of 25 milliseconds to support their testing capabilities. In order to support this request of the test labs, the minimum peak acceleration should be held at 10 gn (at approximately 60 kg). The pulse time calculation will maintain the constant energy of the shock pulse. 16. The resulting accelerations vs. mass for UN 38.3 T4 concepts are shown in Figure 2. The resulting forces vs. mass for the concepts are shown in Figure 3. Figure 4 shows the Energy of the corresponding shock pulses using the formulas described above. As can be seen in these figures, the current discontinuity between large and small batteries (reference paragraph 11 c.) can be eliminated following the energy relationship to a battery mass of approximately 4 kg. 
Figure 2 - Shock Test Proposal 
Figure 3 - UN Shock Test Forces Comparison 
Figure 4 - Energy of Shock Pulse 17. For the proposed shock profile, peak acceleration is based on the battery mass and the force achieved at 50 gn, 12 kg threshold is held constant through the testing. As the peak acceleration varies for battery mass, the duration of the shock pulse shall be adjusted such that the same energy expended in the 50 gn , 12 kg shock pulse is uniform throughout. The maximum acceleration shall be 150 gn and the maximum pulse width at 150 gn shall be 6 mSec at approximately 4 kg.
Directory: wp-content -> uploads uploads -> 587 Return function, r i(X) r i(0) r i(1) r i(2) r i(3) 1 0 2 4 6 Thermal Station, I 2 0 1 5 6 3 0 3 5 6 10 uploads -> The Case Against the nypd’s Quota-Driven ‘Broken Windows’ Policing What Is It? uploads -> For want of a nail uploads -> Police Militarization uploads -> Stop Militarizing Law Enforcement Act of 2014 uploads -> 2017 afoCo Landmark Scholarship Program uploads -> Instructions for the Preparation of Camera-Ready Contributions to the Conference Proceedings uploads -> Medical Radiography Program uploads -> Ihbb asian Championships 2014 middle school bowl Round 4 First Quarter uploads -> Ihbb european Championships 2014 Bowl Round 4 First Quarter Download 284.47 Kb. Share with your friends:
|