Accession Number:

ADA399661

Title:

Development of Validated Crack Measurement System for Vibrating Structures

Descriptive Note:

Final rept. 10 Apr 2001-9 Jan 2002, Phase 1

Corporate Author:

R-TEC ROLLING HILLS ESTATE CA

Personal Author(s):

• Ratwani, Mohan M.

Report Date:

2002-01-01

Pagination or Media Count:

38.0

Abstract:

Analyses were developed to obtain resonant frequencies of panels with and without cracks and subjected to vibratory loads. These analyses were extended to panels with bonded composite patches. A dynamic stress analysis method was developed for panels tested under vibratory loads produced by shaker excitation. Analytically predicted resonant frequencies and stresses compared well with test data provided by Wright Patterson Air Force Base WPAFB. A review of crack growth data. obtained at WPAFB under vibratory loads. indicated that conventional stress intensity factor SIF solutions in AFGROW or other crack growth codes could not be used for accurate prediction of crack growth because of absence of methodology accounting for dynamic stresses and frequency effects. The SIF used in AFGROW were modified to account for these factors. Using the modified SIF, crack growth predictions were made for the WPAFB data on panels with and without bonded composite patches. A good correlation was obtained between predictions and test data. A Visual Crack Measurement system VCMS was used to monitor cracks in the WPAFB tests. An integrated VCMS design was developed. The integrated VCMS will perform crack measurement and structural integrity evaluation functions. The integrated system will also design repair patches for dynamic loading.

Descriptors:

• *CRACKS
• STRESSES
• VIBRATION
• AIRCRAFT
• EXCITATION
• CRACKING(FRACTURING)
• RESONANT FREQUENCY
• CRACK PROPAGATION
• DYNAMIC LOADS
• FATIGUE(MECHANICS)
• STRUCTURAL INTEGRITY
• STRESS INTENSITY FACTORS

Subject Categories:

• Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE