UNCLASSIFIED AD NUMBER LIMITATION CHANGESThe 1100-0 and 7075~T6 aluMnu. alloys and the Borosilicate Glass and Borsic reinforced alumina. ..trix composite materials will also be procured

UNCLASSIFIED

AD NUMBER

LIMITATION CHANGESTO:

FROM:

AUTHORITY

THIS PAGE IS UNCLASSIFIED

AD875390

Approved for public release; distribution isunlimited. Document partially illegible.

Distribution authorized to U.S. Gov't. agenciesand their contractors; Critical Technology; SEP1970. Other requests shall be referred to AirForce Materiels Laboratory, MAMN, Wright-Patterson AFB, OH 45433. This document containsexport-controlled technical data.

afml ltr, 9 mar 1973

§ .

CO

00

^

DEVELOPMENT OF A NONDESTRUCTIVE TESTING

TECHNIQUE TO DETERMINE FLAW CRITICALITY

September 1970

<j>

P. P. Crimmins

Contract F33615-68-C-1705

Sponsored by

Advanced Research Projects Agency AR PA Order No. 1244

Prooram Code Number 8D10

3 OCT 14 1370

tf

This document is subject to special export controls and each transmlttal to foreign governments or foreign nationals may be made only with prior approval of the Manufacturing Technology Division. ^'/tf/T/Zp/iys??/?/?? AS"

4

«•PO|«t »olid propulsion company f. C. BOX 13400 SACRAMENTO, CALIFORNIA 9SB13 • A DIVISION OF AEROJET-CENERAL ©

^ Ö

. .

When Government drawings, specifications, or other data are used for

any purpose other than a definitely related Government procurement operation,

the Government thereby incurs no responsibility nor any obligation whatsoever,

and the fact that the Government may have formulated, furnisheri, or in any vay

supplied the said drawings, specifications, or other data, ia not be regarded,

by implication or otherwise, as in any manner licensing the holder or any

other person or corporation, or conveying any rights or permission to manu-

facture, use, or sell any patented invention that may in any way be related

thereto.

Qualified users may obtain copies of this report from the Defense

Documentation center.

FORSWABD

This report wad prepared by P. P. CrJnmlns of the Advanced Technology

Operations, Metallurgy and Materials Integrity Department, Aerojet Solid

Propulsion Company, Sacramento, California. The research was supported by the

Advanced Research Projects Agency of the Department of Defense and was monitored

by the Air Force Materials Laboratory, MAMN, undev Contract F33615-68-C-1705.

This report covers the period 1 June 1970 through 31 August 1970.

Effective Date of Contract: 1 July 1968

Expiiw-ation Date of Contract: 30 June 1971

Amount of Contract: $208,123

Principal Investigator: C. E. Hartbower

Telephone: (916) 355-6509

mem I ..

TABLE CF CONTENTS

Abstract

I Introduction

II Overall Program Scope

III Technical D cusaion of Work Performed

Page

i

3

5

TABLE LIST

I Test Materials and Conditions

II SWAT-Continuous Recording of Delayed Cracking HY-130

Horizontal Weldment 1 x 18 x 36-in.

6

7

FIGURE LIST

4

5

6

7

8

Relationship Between Stress Intensity Factor and Cumulative

Stress Wave Couni - 18% Nickel tiaraging Steel in Distilled

Water - Sustained Load

Total Stress Wave Emission versus Applied Stress Intensity

Factor - D6AC Steel Tempered at 600oF or 1100°? - 0.29-in.

thick, numbers refer to specimen identity. Rising Load to

Failure

Tr-tal Stress Wave Emission versus Applied Stress Intensity

Factor - D6AC Tempered at llOO'F - 0.10 in. - Numbers refer

to specimen identity. Rising Load to Failure

Unflawed Tensile Specimen for Structural Metals

Typical Part-Through Crack Tensile Specimen for Structural Metals

Single-Edge Notch Specimen for Structural Metals and Crack

Opening Displacement Gage

Standard Sheet-Type-Fatigue Tensile Specimen

SWAT-Continuous Recording of Delayed Cracking HY-130 Horizontal

Weldment 1 x 18 x 36-in.

10

11

12

13

14

15

ii

■ ■■■» m

ABSTRACT

V A brief deacriptlon is presented of the program scope for additional

studies to develop a nondestructive testing technique to determine flaw

criticality. The results of limited instrumentation evaluations for obtaining

real time stress wave emission data are discussed. The fabrication of speci-

mens to be tested at Aerojet and during concurrent programs under ARPA

sponsorship at the University of Michigan and North American Rockwell Corporation

•y is also discussed.

1

ili

■■•- ' :«.«•

I. INTRODUCTION

Thl, pro,r« 1, being co„duct.d to dev.lop oondMtructl« t..tlng

crlterl, rtlch c™ b. .^ioyed to dot.ct a„d loc.t. n... 1„ .ttucturo. .„d ...oo, tbeir potootiol for „aohlog . crltlcl f.Uur. condition, ^o b..lc

tochnoxoglo.. stro,. W.vo tou.ion „d fr.ot.r. „ochonlc, ore bolng .mploy.d to «ccompllol, thl« objoctlvo.

Str.„-„.ve ^..^ „. gener>ted by ^^^^ |Mteriaia ^ ^ ^^^

tho rele«. of kinetic energy fro. e defomntlon mechenls.. The region

.urroundlng tbi. dofo^tlo» .11! .cq„lre. If o„ly te^orerlly. . no. end

«r. eteblc .tree. fleW. Thle n... l^„l.ively d.velopad> „„., fuu ^

give rise to oeclUetlons ^Ich decoy duo to the Inoleetlc bobevlor of the

..terlel. The oleetlc .eve. prop.gete out fro» the .ource end ere detoctod

os «U dleplece^nt. on tho ourfec. of tho .p.cl.en. Ihe.e dlepUc^nt,

otrooe-weve »leelone, con be need to ioc.to tho source of the e.l„lon end provide a aeon, „f M.c..lng the iacnmM of defomatlon ^^ ^ ^^^

I-lneer ele.tlc fracture machanlc. 1. an onglnoarlng „ethod of detemlnlng

the streeee. In the vicinity of e .tree, conc.ntr.tlon. Ihoe. .dutlon, ,r.

d.v.loped through eppUcetlon of oleetldty theory end they detomlne linear

rel.tlon.hlp. between .tr... function, „d dl.^.lon.1 function, of the flew

Thl. .trea,-lnten.lty fector" which depend, on the fUw'a .1M, 8hape and

orlantetlon with re.pect to loed end/or .peclMn goo^try. 1. a «een. of defining

the rat. of euppiy of .„Uebio energy for creek propegatlon In term, of the

•PPlIod atre,. (Uld within tho .peclaen. The advantage of ualng the atro.a-

ntonelty factor (K) 1, th.t It My be eveiuefd In MlM of the appUed atre...

the crack ,1« a„d tho .pectaen dlM„.lon. and 1. thu. reduced to a .trees

enaly,!. probl... Through thl. engineering „ethod, any probl«, .olvbl. by llne.r .tree. an.ly.l. l. c.?.bu ot „.^ .n.ly2eJ ^ , t

point of view.

Page 1

-'-..«M.

Durini th« previous ycarf studl». undar thli contr«ct(Raf'^ it was

d«i«aiiitratad that tha itraas wava data may be paramenrically related to stress-

Intenoity factors. These relationships ate being further investigated during

the present etudy for a variety of materials and use conditions. This report

covarr Che progress during the period of June through August 1970.

Ref.: Green, A. T. and Martbower, C. E., Development of a Nondestructive Testing Technique to Determine Pi»- Critlcallty, May 1970, Interim Report under Contract P336I5-<8-C-1 05.

Page 2

■

H. OVERALL PROGRAM srm>f

The progr^n. to b. performed to develop the Stress-Weve-Emission fech-

nology for a nondestructive Inspection systen. Is divided into three phases-

a brief description of the work planned in each is shown below.

PHASE I - SPECIMEN FABRICATION

During Phase I. the species for testing in subsequent progran. phases

will be fabricated. The 1100-0 and 7075~T6 aluMnu. alloys and the Borosilicate

Glass and Borsic reinforced alumina. ..trix composite materials will also be

procured during this phase. The D6aC steel and 6A1-4V titanium materials are

presently available from the first year's study under Contract F33615-68-C-1705

the results of which were published in Reference (1). The materials and

appropriate thicknesses and conditions to be tested during the program at Aerole^ are shown in Table I.

In addition to the tensile, single-edge-notch tensile and part-through-

crack tensile specimens to be tested at Aerojet, standard sheet type fatigue

specimens will be fabricated and delivered to the University of Michigan and

North American Rockwell Corporation for their programs.

PHASE II - SPECIMEN TESTING AND DATA ANALYSIS

During Phase II. specimen testing will be performed and will be accompanied

by continuous data analysis throughout Phase II. Primary emphasis will be to

develop relationships between incremental fracture and failure, and significant

stress wave emission characteristic, whlct en be employe, to locate and assess

flaw crlticallty in structures for a v.ru..y of materials and use conditions.

Stress wave characteristic, which will b. inv.tlg.t.d include amplitude

cumulative count and rat. of occurranc. Th... ch.r.ct.ristic. will be related

to fractur. b.h.vlor through fracture machanlc.. It 1. expected that further

Page 3

^PpM«*Hl'Mamil.K WtWW* fc-. l W»! I

refinement in such relationships as developcu during the first year's program

and shown in Figures 1 through 3 will be made. Other stress wave emission

characteristics which will be studied Include wave shape and frequency content.

Concurrently, stress wave emission attenuation, discrimination in high

noise backgrounds, and source trlangulation techniques will also be evaluated.

PHASE III - SUIMARY TECHNICAL REPORT

The Summary Technical Rf u.. including results from this and the first

year's program will be prepared during Phase III.

Page 4

II1- TECHNICAL DISCUSSION OF WORK PERFORMED

PHASE I - SPECIMEN FABRICATION

The D6aC steel and 6A1-4V titanium sheet and plate materials were

available from the first year's program while the 7075-76 aluminum, borosilic^te

glass and the Borsic reinforced aluminum matrix composite materials were procured

for this program. Fabrication of the tensile (Figure 4), single-edge-notch

tensile (Figure 5) and part-through-crack tensile (Figure 6) specimens has been

initiated and is proceeding. The borosilicate glass and composite materials have

been ordered, but not received.

During the reporting period, the standard, sheet-type fatigue specimens

(Figure 7) required foi programs at the University of Michigan and North American

Rockwell Corporation were also fabricated and delivered.

PHASE II - SPECIMEN TESTING AND DATA ANALYSIS

So tests were performed during this period using test materials specifically

procured for the program. However, instrumentation evaluations were continued

where possible during tests conducted as part of other studies.

The most significant of these evaluations are those being conducted to

evaluate instrumentation systems which will provide a continuous, long-term moni-

toring capability with SWE data output which can be employed to relate the stress

wave data to applied stress Intensity and incremental crack area. As indicated

in Figures 1 through 3, cumula'-lve stress wave emission count appears a signifi-

cant parameter for this purpose. During the reporting period, a SWE monitoring

system has been assembled which will meet this requirement. The system has been

employed to monitor delayed cracking in weldments. Typical data obtained from

these tests which illustrates the discontinuous nature of the cracking, is shown

In Table 2 and Figure 8. Additional evaluations of this system and other Instru-

mentation components will be performed when the specimens for thii program arc

available for testlag.

Page 5

Material

D6aC Steel

(0.1 and 0.3-in.

thick)

TABLE I

TEST MATEFIALS AND CONDITIONS

Modulus

30 x 10

Approximate Ultimate Streugth (ksl)

220

280

Borslc Reinforced Aluminum

Compos it a

(0,1-in. thick)

32 x 10 1A0

Ti-6A1-4V

(0.1 and 0.25-ln.

thick)

16 x 10 140

17'

7075-16 Aluminum

(0.09 and 0.25-in.

thick)

10.A x 10l 85

Borosilicate Glass 9.5 x 10

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STRESS INTENSITY (KSI-IN.1/?)

210

Figure 1. Relationship Between Stress Intensity Factor and Cumulative Stress Wave Count - 18% Nickel Maraglng Ste-t In Distilled Water * Sustained Load.

Page 8

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APPLIED STRESS INTENSITY (KSI - IN/2)

Figure 2. Total Stress Wave Emission versus Applied Stress Intensity Factor - D6AC Steel Tempered at 600oF or 1100CF - 0.29-ln. thick, numbers refer to specimen Identity. Rising Load to Failure.

Page 9

APPLIED STRESS INTENSITY (KSI - IN/7)

Figure 3. Total Stress Wave Emission versus Apulied Stress Intensity Factor - D6AC Tempered at llOO^F - 0.10 in. - Numbers refer to specimen identity. Rising Load to Failure.

Page 10

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SPECIMEN IDENTIFICATION (2 PLACES)

Figure 4. Unflawed Tensile Specimen for Structural Metals

Page 11

1.250!;^ DIA (TYP)

-H U- THK

.50 R. (TYP)

PART-THROUGH.CRACK

SPECIMEN IDENTY (2 PLACES)

Figure 5. Typical Part-Through Crack Tensile Specimen for Structural Metals

Page 12

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Page 13

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