Response Spectrum Options for Dynamic Shock Analysis
Use the following options to define the response spectrum curve for the base excitation. These items appear on the Response Spectrum tab on the Shock Analysis Definition dialog box:
• 
—Select a function of frequency to define the response spectrum curve.
—Select a function of frequency to define the response spectrum curve.The default response spectrum curve function is uniform, which means the frequency dependence of the base excitation is uniform over the frequency range.
To select a different function, click . The Functions dialog box appears. You can select an existing function or click New to define a new function.
. The Functions dialog box appears. You can select an existing function or click New to define a new function.• Spectrum of—Select one of these quantities for the response spectrum curve:
◦ Displacement
◦ Velocity
◦ Acceleration
• Modal Combination Method—Select the method the engine uses to combine modes when calculating results:
◦ SRSS—the square root of the sum of the squares
◦ Absolute Sum—the sum of the absolute values of the contributions of each mode