This part of ISO 21940 specifies methods for determining machine vibration sensitivity to unbalance and provides evaluation guidelines as a function of the proximity of relevant resonance rotational speeds to the operating speed. This part of ISO 21940 is only concerned with once-per-revolution vibration caused by unbalance. It also makes recommendations on how to apply the numerical sensitivity values in some particular cases.<\/p>\n
It includes a classification system that can be applied to machines which is related to their susceptibility to a change in unbalance. Machines are classified into three types of susceptibility and five ranges of sensitivity. The sensitivity values are intended for use on simple machine systems, preferably with rotors having only one resonance speed over their entire operating speed range. The sensitivity values can also be used for machines that have more resonance speeds in their operating speed range if the resonance speeds are widely separated (e.g. by more than 20 %).<\/p>\n
The sensitivity values given are not intended to serve as acceptance specifications for any machine group, but rather to give indications regarding how to avoid gross deficiencies as well as specifying exaggerated or unattainable requirements. They can also serve as a basis for more involved investigations (e.g. when in special cases a more exact determination of the required sensitivity is necessary). If due regard is paid to the values given, satisfactory running conditions can be expected in most cases.<\/p>\n
The consideration of the sensitivity values alone does not guarantee that a given magnitude of vibration in operating is not exceeded. Many other sources of vibration can occur which lie outside the scope of this part of ISO 21940.<\/p>\n
| PDF Pages<\/th>\n | PDF Title<\/th>\n<\/tr>\n | ||||||
|---|---|---|---|---|---|---|---|
| 6<\/td>\n | Foreword <\/td>\n<\/tr>\n | ||||||
| 8<\/td>\n | Introduction <\/td>\n<\/tr>\n | ||||||
| 9<\/td>\n | Section sec_1 Section sec_2 Section sec_3 Section sec_4 Section sec_4.1 1\tScope 2\tNormative references 3\tTerms and definitions 4\tMachine susceptibility classification 4.1\tGeneral <\/td>\n<\/tr>\n | ||||||
| 10<\/td>\n | Section sec_4.2 Section sec_4.3 Section sec_4.4 Section sec_4.5 Table tab_1 Section sec_5 Section sec_5.1 4.2\tType I: Low susceptibility 4.3\tType II: Moderate susceptibility 4.4\tType III: High susceptibility 4.5\tMachine susceptibility correction factors 5\tModal sensitivity 5.1\tGeneral <\/td>\n<\/tr>\n | ||||||
| 11<\/td>\n | Section sec_5.2 Table tab_2 Section sec_5.3 Section sec_5.4 Section sec_5.4.1 Section sec_5.4.2 5.2\tModal sensitivity ranges 5.3\tCharacteristics of modal sensitivity ranges 5.4\tValues of modal sensitivity <\/td>\n<\/tr>\n | ||||||
| 12<\/td>\n | Table tab_b Figure fig_1 Section sec_5.4.3 <\/td>\n<\/tr>\n | ||||||
| 13<\/td>\n | Table tab_c Figure fig_2 <\/td>\n<\/tr>\n | ||||||
| 14<\/td>\n | Table tab_3 Section sec_5.4.4 <\/td>\n<\/tr>\n | ||||||
| 15<\/td>\n | Table tab_d Figure fig_3 Table tab_4 Section sec_5.5 5.5\tOperating speed <\/td>\n<\/tr>\n | ||||||
| 16<\/td>\n | Table tab_e Figure fig_4 Table tab_5 <\/td>\n<\/tr>\n | ||||||
| 17<\/td>\n | Section sec_5.6 Table tab_f Figure fig_5 5.6\tTransient speed <\/td>\n<\/tr>\n | ||||||
| 18<\/td>\n | Section sec_6 Section sec_6.1 Section sec_6.2 Section sec_6.3 6\tExperimental determination of modal sensitivity near resonance speed under operational conditions 6.1\tGeneral 6.2\tNyquist diagram procedure 6.3\tBode diagram procedure <\/td>\n<\/tr>\n | ||||||
| 19<\/td>\n | Table tab_h Figure fig_6 Section sec_7 7\tNumerical values for the local sensitivity <\/td>\n<\/tr>\n | ||||||
| 20<\/td>\n | Section sec_8 Section sec_8.1 Section sec_8.2 8\tExperimental determination of the local sensitivity 8.1\tGeneral 8.2\tProcedure <\/td>\n<\/tr>\n | ||||||
| 21<\/td>\n | Section sec_9 9\tDamped unbalance sensitivity analysis <\/td>\n<\/tr>\n | ||||||
| 22<\/td>\n | Annex sec_A Annex sec_A.1 Annex sec_A.2 Annex sec_A.3 Annex\u00a0A \n(informative)<\/p>\n Explanations of terms <\/td>\n<\/tr>\n | ||||||
| 24<\/td>\n | Annex sec_B Figure fig_B.1 Table tab_B.1 Annex\u00a0B \n(informative)<\/p>\n Example of polar plot diagram procedure <\/td>\n<\/tr>\n | ||||||
| 25<\/td>\n | Annex sec_C Annex sec_C.1 Annex sec_C.2 Annex\u00a0C \n(informative)<\/p>\n Examples of classification according to modal sensitivity <\/td>\n<\/tr>\n | ||||||
| 26<\/td>\n | Annex sec_D Annex\u00a0D \n(informative)<\/p>\n Example of mathematical model applied unbalance <\/td>\n<\/tr>\n | ||||||
| 27<\/td>\n | Reference ref_1 Reference ref_2 Reference ref_3 Reference ref_4 Reference ref_5 Reference ref_6 Bibliography <\/td>\n<\/tr>\n<\/table>\n","protected":false},"excerpt":{"rendered":" Mechanical vibration. Rotor balancing – Susceptibility and sensitivity of machines to unbalance<\/b><\/p>\n |