Location

Brunswick, ME

Start Date

1-1-1997 12:00 AM

Description

In order to use composite materials in aeronautical turbo engines, the resistance to impact damage caused by soft body (birds) must be understood. In this work the subperforation flat-wise soft body impact resistance of two kinds of carbon fiber/PEEK systems were evaluated using a gelatin projectile. Tested systems were AS4/PEEK (APC-2/AS4, ICI-Fiberite) and AS4/PEEK+IL, which consists of APC-2 prepreg and PEEK film inserted between layers as an interleave. To investigate the effects of the stacking sequence on resistance, three lay-ups- (0/+30/0/−30)s, (0/+60/0/−60)s, and (0/+45/90/−45)s- were tested. A gas gun system was used for the impact tests, where the velocity range was between 90 and 190 m/s. The mass of the projectile was about 3 g. The projected damage areas were measured with an ultrasonic C-Scan system. The characteristics of the soft body impact damages are evaluated by comparisons of the damages caused by the aluminum and gelatin projectiles. The relative impact resistance was discussed with the data measured in the previous hard body and gelatin impact tests. The impact damage caused by the gelatin projectile was almost the same as the damage shape caused by the aluminum projectile, but the gelatin impact resulted in a smaller projected damage area. The relationship between damage area(DA) and impact energy (IE) is linear for both the gelatin impact and the aluminum bullet impact. The DA/IE of gelatin impact was less than that for the aluminum bullet impact, and the gelatin impact indicated higher impact energy thresholds. The basic deformation mode of the aluminum and the composite specimens considered were pure bending at a lowest natural frequency without node diameters or circles, but in the frequency domain, the behavior of composites was more complicated than that of aluminum plates. The effects of stacking sequence system (T200/#3900) indicated a different relationship than that for the CF/PEEK systems. The impact resistance can be assessed with the proposed non dimensional stacking parameter βT2 and the value of (DA/IE)/βT2 which is independent of both fiber angle and lamina thickness. The CF/PEEK systems indicated a good proportional correlation of (DA/IE)/βT2 between the high velocity impact to the low velocity and the gelatin impact.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

16B

Chapter

Chapter 7: New Inspection Procedures

Section

New Techniques

Pages

1885-1892

DOI

10.1007/978-1-4615-5947-4_246

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Ultrasonic Characterization of Soft Body Impact Damage on CF/PEEK Laminates with Gelatin Projectiles

Brunswick, ME

In order to use composite materials in aeronautical turbo engines, the resistance to impact damage caused by soft body (birds) must be understood. In this work the subperforation flat-wise soft body impact resistance of two kinds of carbon fiber/PEEK systems were evaluated using a gelatin projectile. Tested systems were AS4/PEEK (APC-2/AS4, ICI-Fiberite) and AS4/PEEK+IL, which consists of APC-2 prepreg and PEEK film inserted between layers as an interleave. To investigate the effects of the stacking sequence on resistance, three lay-ups- (0/+30/0/−30)s, (0/+60/0/−60)s, and (0/+45/90/−45)s- were tested. A gas gun system was used for the impact tests, where the velocity range was between 90 and 190 m/s. The mass of the projectile was about 3 g. The projected damage areas were measured with an ultrasonic C-Scan system. The characteristics of the soft body impact damages are evaluated by comparisons of the damages caused by the aluminum and gelatin projectiles. The relative impact resistance was discussed with the data measured in the previous hard body and gelatin impact tests. The impact damage caused by the gelatin projectile was almost the same as the damage shape caused by the aluminum projectile, but the gelatin impact resulted in a smaller projected damage area. The relationship between damage area(DA) and impact energy (IE) is linear for both the gelatin impact and the aluminum bullet impact. The DA/IE of gelatin impact was less than that for the aluminum bullet impact, and the gelatin impact indicated higher impact energy thresholds. The basic deformation mode of the aluminum and the composite specimens considered were pure bending at a lowest natural frequency without node diameters or circles, but in the frequency domain, the behavior of composites was more complicated than that of aluminum plates. The effects of stacking sequence system (T200/#3900) indicated a different relationship than that for the CF/PEEK systems. The impact resistance can be assessed with the proposed non dimensional stacking parameter βT2 and the value of (DA/IE)/βT2 which is independent of both fiber angle and lamina thickness. The CF/PEEK systems indicated a good proportional correlation of (DA/IE)/βT2 between the high velocity impact to the low velocity and the gelatin impact.