ESDU 73010+Amendment(A)-1973 承受模拟声学载荷的钛及钛合金结构元件的耐久性

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73010



ENDURANCE OF TITANIUM AND TITANIUM ALLOY STRUCTURAL ELEMENTS

SUBJECTED TO SIMULATED ACOUSTIC LOADING

1. NOTATION

2. NOTES

This Item gives the results of fatigue tests on titanium alloy specimens, typical of aircraft structural elements,

excited by narrow-band loading of random amplitude with zero mean load to simulate stress response to

acoustic loading.

The plain specimens, illustrated in Figure 1a, are representative of sheet material away from the effects of

attachments. The built-up specimens, illustrated in Figures 1b to 1e represent conditions in sheet material

attached without jointing compound to stiffeners, where adjacent plates are vibrating in phase.

In Figures 2 to 5, is plotted against for test results grouped according to the type of structural

element, material and method of attachment as shown in Table 5.1. A straight line fitted by the least squares

method and bands enclosing 95 per cent of the data, drawn for each group of test points, have been given

for guidance; they should not be used directly for estimating life because due account must be taken of

scatter. Figure 6 shows the relative endurances for the different groups. Extrapolation of the mean lines to

higher endurances than indicated, where few data are available, is expected to lead to an underestimate of

endurance.

The reference position for is taken as a point on the failure line away from the effects of stress

concentration and from fretting at fasteners; the test points plotted represent either mean stresses over the

areas covered by monitoring strain gauges affixed across the failure line away from fasteners, or stresses

at that position estimated after calibration from strain monitors located elsewhere. When using this Item to

estimate a life using a root mean square stress level obtained from Item Nos 72005, 73014 or 74026, it is

recommended that the calculated value of stress in close proximity to the failure position should be assumed

to be the same as that at the failure position. In practice, away from the effects of stress concentration, this

approximation is within the range of accuracy of the simple theory used for stress prediction in these Data

Items.

Details of the test methods and specimens are given in appendices as listed below.

Typical failure locations are shown in Figure 1.

The loading simulated for the fastened-skin specimens is only that for modes where adjacent panels are in

phase. Care should be taken in using the data for modes involving twisting of the stiffeners.

root mean square value of stress at reference position N/m2 lbf/in2

equivalent endurance, taken as half number of zero crossings of

stress-time function before failure cycles cycles

Appendix A– Tests on plain specimens

Appendix B– Tests on fastened-skin specimens

Appendix C– Description of materials

Srms

Srms Nr

Srms

Issued April 1973

With Amendment A

ESDU product issue: 2007-02. For current status, contact ESDU. Observe Copyright.

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73010



In the Addendum to this Item, data are presented on the effect of elevated temperature on the endurance of

titanium alloy structural elements under simulated acoustic loading. The Addendum also includes additional

room temperature fatigue test data, not presented in the main body of this Item, on both plain specimens

and riveted-skin specimens.

3. INTERPRETATION OF THE RESULTS

3.1 Effect of Method of Attachment

Skin specimens attached to stiffeners by mushroom-headed rivets showed significantly greater endurance

and less scatter than resistance spot-welded specimens. The resistance spot-welded specimens in turn

showed slightly greater endurance and considerably less scatter than gas tungsten-arc spot-welded*

specimens. It is evident that the gas tungsten-arc process requires further development before it can be used

with confidence for titanium structures in a high noise environment.

3.2 Effect of Material Specification and Thickness

The available data for different materials are not directly comparable because of differences in specimen

configuration and thickness. The large differences between the results for Ti-2Cu (Aged) (Figures 3 and 4)

and C.P. Ti (Figure 5) are thought to be due to the effects of skin thickness on spot-weld performance rather

than to the difference in material.

3.3 Effect of Heat Treatment and Grain Direction

The tests on the Ti-2Cu material show that for this material a substantial increase in endurance is obtained

by spot welding before, rather than after, ageing. For these specimens slightly greater endurance was

obtained for spot welds stressed in a transverse rather than a longitudinal grain direction.

3.4 Effect of Test Frequency

The mean response frequency for each type of test specimen is indicated in Figures 2 to 5. The range of'

frequencies is too small for any effects to be identified.

3.5 Effect of Elevated Temperature

A limited number of tests on Ti-2Cu (Aged) specimens was carried out at 250°C. These indicate that

temperatures up to 250°C have little effect on the endurance of this material. In the Addendum, test data

for Ti-6Al-4V (annealed) specimens at 316°C are presented. These data show that, for a given stress level,

the elevated temperature endurance is lower than that for room temperature.

3.6 Data for Plain Specimens

Tests on the plain specimens under constant amplitude loading, included on Figure 2, show a very marked

discontinuity in the S-N curve at alternating stresses of about 450 MN/m2 (65 000 lbf/in2). The increased

scatter of the random-loading test results at r.m.s. stresses of about 250 MN/m2 (35 000 lbf/in2) in Figure

2 is believed to be associated with this discontinuity.

*The gas tungsten-arc spot welding process is described in Reference 5.

ESDU product issue: 2007-02. For current status, contact ESDU. Observe Copyright.

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73010



4. DERIVATION AND REFERENCES

Derivation

5. SUMMARY OF DATA PRESENTED

1. CUMMINS, R.J.

EATON, D.C.G. Unpublished work by British Aircraft Corporation, May 1969.

2. ARTUSIO, G.

et al. Unpublished work by Fiat, January 1971.

3. CUMMINS, R.J.

EATON, D.C.G. Unpublished work by British Aircraft Corporation, January 1971.

4. LAMBERT, R.F.

THOMSON, A.G.R. Acoustic fatigue design data, Part 3. AGARD-AG-162 Part 3, 1973.

References

5. – Welding Handbook, Part 2, welding processes – gas, arc and resistance.

27,20/21 5th Ed. American Welding Society, 1964.

TABLE 5.1

Fig.

No. Type of

Element Material Number of

Attachment

Rows Attachment Type Thickness Response

Frequency

(Hz)

mm in

2Plain Ti-6Al-4V (Ann) ––1.52 (0.06) 300

3Riveted skin Ti-2Cu (Aged) 1 Countersunk

Monel

rivets

No jointing compound

(0.71) 0.028 260

2 Snap-head

Monel

rivets

(0.71) 0.028 160

4Welded skin Ti-2Cu (Aged) 1 Resistance

spot welds (0.71) 0.028 250

5Welded skin C.P.Ti 2 Resistance

spot welds (0.41) 0.016 190

2Gas

tungsten-arc

spot welds

(0.41) 0.016 180

1 (0.41) 0.016 175

6ASSEMBLAGE OF DATA PLOTTED ON FIGURES 2 to 5

ESDU product issue: 2007-02. For current status, contact ESDU. Observe Copyright.

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标签： #合金 #结构 #钛合金

摘要：

ESDU 73010+Amendment(A)-1973 是英国工程科学数据单元（ESDU）发布的一项工程技术标准，专门针对承受模拟声学载荷的钛及钛合金结构元件的耐久性进行评估与设计。该标准提供了在模拟声学环境下钛及钛合金材料的疲劳寿命预测方法，涵盖了声振联合载荷对结构件疲劳行为的影响，适用于航空航天、发动机短舱、机身板壳及声学衬板等关键部件的耐久性分析与验证。文档中包含典型的声学载荷谱定义、材料特性参数、疲劳试验数据处理准则以及结构元件的许用应力与寿命评估模型。通过该标准，工程师能够更准确地评

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ESDU 73010+Amendment(A)-1973 承受模拟声学载荷的钛及钛合金结构元件的耐久性

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