Transient Capture Andy Cogbill,

Transcription

1 Transient Capture Andy Cogbill,

2 Transient Capture History Designed around drop shock machines Use Primary use is still drop shock testing Package testing Product Life testing Pass/Fail production testing Recording Field Data Transient Events

3 Drop Shock Machines Pulse shape determined by drop pads Flat Elastomer, designed to produce half-sine Lead, designed to produce sawtooth pulses Lead can be reshaped/molded over and over Air Cylinders or a crumple material designed to produce square and trapezoid pulses Pulse width determined by drop pads Lighter objects will generally see a wider pulse Shaped lead produces different pulse widths (saw tooth) Deflection (thickness, density, etc.) of elastomer determines pulse width (half-sine) Pulse Acceleration determined by: Pads, DUT, Frequency content, Drop Height (velocity), Any assist mechanisms (bungee cords)

4 Transient Capture Overview Record your transient events Transient capture provides a simple interface to record transient events. Select a trigger level, slope, channel, and duration Simple Independent Triggers Trigger the capture on the capture channel, or use an independent channel as a dedicated trigger Open Loop Output Use the open loop sine chirp or random output to drive a modal shaker Shock Response Spectra Analysis (Optional) VR9302 Specify and display a SRS spectrum. Analyze SRS of each pulse as it is captured

5 Transient Capture - Trigger Set your Trigger Channel Only one trigger channel can be used Set your desired trigger level in G s Capture Window Capture total in milliseconds Hold Off timer Filter Many filter types available Sample Rate Set to automatic Should be at least 10 times the analysis frequency Frequency Analysis Set Minimum and Maximum Plotted Frequency (Auto Scale Range)

6 Transient Capture Trigger+ Additional Filtering Notes Antialias and FIR (brickwall) filters are applied AFTER the capture. This can result in a capture where the defined trigger level is not plotted due to the filtering. IIR (Butterworth, etc.) filters are applied before the capture. Unfiltered and filtered channel traces can be displayed simultaneously

7 Transient Capture - Output Output Use the Output to Drive a modal shaker Choose and Output type Burst Random Linear Chirp Exponential Chirp Pulse Duration in milliseconds Output Level in millivolts Choose your output frequency range

8 Transient Capture - Tolerance Create a Tolerance Envelope Overall Width Direction and Peak Amplitude Shock Pulse Shape Pulse Alignment Offset the Start of the Pulse from the Trigger Time Tolerances Set the Min and Max MIL-STD Pulse Limits are predefined Individual Pre and Post Pulse Tolerances

9 Transient Capture Breakpoints Breakpoint Table Define the Breakoints of the Desired SRS Curve Tolerances Use the same Tolerances for all Breakpoints Import Import Frequency and Amplitude Breakpoints from a Text File

10 Transient Capture SRS SRS Analysis Define the SRS Analysis Parameters Define Damping and Q values used in the SRS Choose Analysis Range Frequency Range Breakpoint Frequencies If analyzing the Frequency Range, then Define the Range and the Resolution

11 Transient Capture Data Storage Directories Data Storage Directory Report Storage Directory File Name Format Data Saves Save every pulse Graph Annotation Lines Additional Information saved with the Data

12 Transient Capture Tables Tables Automatically save tabular spreadsheet data Update Interval Each table saves at individual intervals

13 Transient Capture

14 Transient Capture Graphs Text Window Rise Time and Fall Time are defined by Mil-Std 810 as 10-90% Default Peak G value is the peak value between the defined trigger level and the first 0 crossing point. Channel Peak can be displayed using [PARAM:Ch1Peak] and will be the peak in the full captured event