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The Job Monitor gives a brief summary of the automatic time incrementation used in the analysis for each increment. The information is written as soon as the increment is completed, so that you can monitor the analysis as it is running. This facility is useful in large, complex problems. The information given in the Job Monitor is the same as that given in the status file (DynCrane.sta).
Examine the Job Monitor and the printed output data file (DynCrane.dat) to evaluate the analysis results.
- Job monitor
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In the Job Monitor, the first column shows the step number and the second column gives the increment number. The sixth column shows the number of iterations Abaqus/Standard needed to obtain a converged solution in each increment. Looking at the contents of the Job Monitor, we can see that the time increment associated with the single increment in Step 1 is very small. This step uses no time, because time is not relevant in a frequency extraction procedure.
The output for Step 2 shows that the time increment size is constant throughout the step and that each increment requires only one iteration. The bottom of the Job Monitor is shown in Figure 1.
Figure 1. Bottom portion of the Job Monitor: cargo crane dynamic analysis.
- Data file
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Click the tab in the Job Monitor to display the data file in a tabbed page at the bottom of the dialog box. The primary results for Step 1 are the extracted eigenvalues, participation factors, and effective mass, as shown below.
E I G E N V A L U E O U T P U T MODE NO EIGENVALUE FREQUENCY GENERALIZED MASS COMPOSITE MODAL DAMPING (RAD/TIME) (CYCLES/TIME) 1 1773.4 42.112 6.7023 151.92 0.0000 2 7016.8 83.766 13.332 30.206 0.0000 3 7644.1 87.431 13.915 90.400 0.0000 4 22999. 151.65 24.136 250.64 0.0000 5 24714. 157.21 25.020 275.88 0.0000 6 34811. 186.58 29.695 493.15 0.0000 7 42748. 206.76 32.906 1106.4 0.0000 8 46473. 215.58 34.310 86.173 0.0000 9 47446. 217.82 34.667 2577.2 0.0000 10 56050. 236.75 37.680 3569.2 0.0000 .... 25 2.26885E+05 476.32 75.809 207.46 0.0000 26 2.42798E+05 492.75 78.423 127.02 0.0000 27 2.84057E+05 532.97 84.825 1240.8 0.0000 28 2.92450E+05 540.79 86.069 330.74 0.0000 29 3.13943E+05 560.31 89.176 272.39 0.0000 30 3.64774E+05 603.97 96.124 64.971 0.0000The highest frequency extracted is 96 Hz. The period associated with this frequency is 0.0104 seconds, which is comparable to the fixed time increment of 0.005 seconds. There is no point in extracting modes whose period is substantially smaller than the time increment used. Conversely, the time increment must be capable of resolving the highest frequencies of interest.
The column for generalized mass lists the mass of a single degree of freedom system associated with that mode.
The table of participation factors indicates the predominant degrees of freedom in which the modes act. The results indicate, for example, that mode 1 acts predominantly in the 3-direction.
P A R T I C I P A T I O N F A C T O R S MODE NO X-COMPONENT Y-COMPONENT Z-COMPONENT X-ROTATION Y-ROTATION Z-ROTATION 1 -6.11696E-04 -6.14521E-03 1.4284 0.71335 -6.0252 -3.37773E-02 2 0.18470 -0.25677 8.31954E-04 1.68388E-03 -6.05012E-03 -1.6826 3 -0.17440 1.5515 4.88123E-03 -8.04039E-03 3.24495E-02 9.2746 4 -8.68256E-05 -9.61259E-03 8.23615E-02 0.21604 1.2334 -2.97905E-02 5 -3.80675E-03 1.13829E-03 -3.04304E-02 -0.59220 1.7593 -2.20144E-02 6 3.71618E-02 -0.35674 6.05241E-03 -1.67946E-02 6.71292E-03 -0.96432 7 -2.48508E-03 -1.58332E-03 6.19821E-02 5.09235E-02 -0.29901 -6.65849E-04 8 -7.03851E-02 2.31655E-02 0.72459 0.49275 -3.8778 6.69085E-02 9 3.59820E-02 -2.34811E-02 2.23695E-02 1.47243E-02 -0.12808 6.65955E-04 10 3.48679E-02 4.02884E-02 1.96398E-02 1.09545E-02 -6.84066E-02 3.72037E-02 .... 25 -8.25375E-02 -0.22218 -3.54545E-02 3.39238E-02 -2.18245E-02 -0.18688 26 -1.98905E-02 -0.35111 4.61269E-02 -2.12563E-02 -1.27532E-02 -0.18939 27 1.71772E-02 2.51340E-02 2.26524E-02 -1.02593E-02 -4.31559E-02 2.78870E-02 28 4.73352E-02 2.79265E-02 -0.11860 5.19825E-02 0.24175 -1.12541E-04 29 9.83488E-03 -3.64823E-03 4.65504E-03 -3.17284E-03 -1.56708E-02 -2.82848E-03 30 4.83733E-02 1.85495E-02 0.13426 -2.21861E-02 -0.35882 -1.87612E-02The table of effective mass indicates the amount of mass active in each degree of freedom for any one mode. The results indicate that the first mode with significant mass in the 2-direction is mode 3. The total modal effective mass in the 2-direction is 378.26 kg.
E F F E C T I V E M A S S MODE NO X-COMPONENT Y-COMPONENT Z-COMPONENT X-ROTATION Y-ROTATION Z-ROTATION 1 5.68458E-05 5.73721E-03 309.98 77.309 5515.3 0.17333 2 1.0304 1.9915 2.09072E-05 8.56481E-05 1.10567E-03 85.521 3 2.7495 217.62 2.15392E-03 5.84420E-03 9.51888E-02 7776.2 4 1.88952E-06 2.31599E-02 1.7002 11.699 381.31 0.22244 5 3.99791E-03 3.57461E-04 0.25547 96.753 853.88 0.13370 6 0.68104 62.759 1.80648E-02 0.13910 2.22229E-02 458.58 7 6.83296E-03 2.77373E-03 4.2507 2.8692 98.926 4.90544E-04 8 0.42691 4.62440E-02 45.243 20.923 1295.8 0.38578 9 3.3366 1.4209 1.2896 0.55874 42.275 1.14296E-03 10 4.3393 5.7933 1.3767 0.42830 16.702 4.9402 .... 25 1.4133 10.241 0.26078 0.23875 9.88154E-02 7.2457 26 5.02526E-02 15.658 0.27026 5.73911E-02 2.06589E-02 4.5558 27 0.36612 0.78387 0.63672 0.13060 2.3110 0.96499 28 0.74106 0.25794 4.6523 0.89371 19.329 4.18897E-06 29 2.63473E-02 3.62545E-03 5.90262E-03 2.74218E-03 6.68933E-02 2.17924E-03 30 0.15203 2.23557E-02 1.1711 3.19804E-02 8.3651 2.28687E-02 TOTAL 22.198 378.26 373.69 269.78 8348.4 8518.0The total mass of the model is given earlier in the data file and is 414.34 kg.
To ensure that enough modes have been used, the total effective mass in each direction should be a large proportion of the mass of the model (say 90%). However, some of the mass of the model is associated with nodes that are constrained. This constrained mass is approximately one-quarter of the mass of all the elements attached to the constrained nodes, which, in this case, is approximately 28 kg. Therefore, the mass of the model that is able to move is 385 kg.
The effective mass in the x-, y-, and z-directions is 6%, 98%, and 97%, respectively, of the mass that can move. The total effective mass in the 2- and 3-directions is well above the 90% recommended earlier; the total effective mass in the 1-direction is much lower. However, since the loading is applied in the 2-direction, the response in the 1-direction is not significant.Tip: To determine the mass of the elements attached to the constrained nodes, switch to the Mesh module, click the query tool 
, and select Mass properties from the list of
general queries. In the prompt area, select Select mesh
entities, and select the six elements attached to the constrained
nodes. The total mass is displayed in the message area (114 kg).
The data file does not contain any results for the modal dynamics step, because all of the data file output requests were suppressed.