ML18100A893

From kanterella
Jump to navigation Jump to search
Rev 0 of Fatigue Evaluation.
ML18100A893
Person / Time
Site: Salem  PSEG icon.png
Issue date: 12/23/1993
From:
MPR ASSOCIATES, INC.
To:
Shared Package
ML18100A891 List:
References
108-32-02, 108-32-02-R00, 108-32-2, 108-32-2-R, NUDOCS 9402280231
Download: ML18100A893 (9)
v • d • e


Text

MPR ASSOCIATES, INC.

320 King Street, Alexandria, VA 22314 CALCULATION TITLE PAGE PAGE 1 OF Cj Project TASKNO~

'So.. ~e,M. E'DC:s- L\ricr 02'c..lCtj to& Calculation Title CALCULATION NO.

REVISION PAGE NO. PREPARER(S)/ CHECKER(S)/ REVIEWER(S)/

NO. AFFECTED DATE DATE DATE cp 11.fff /  :

~~*~ ~c;;~

Ji/n~J. ., i. /1.3/0,3

l~'Z-'3(13 .

.. *1

' ., \ ,

.. ~ . . r* .  ;

l. .. l.i*. .- *_*

~;. ~ :"s. ... ... . .

'1*

,"':-1

': ***-~ r  ;"*,';:

  • ~==~=======~=======~===========~

~-----~------

402280231 940215 DR ADOCK 05000272 1

I p PDR

. MPR Associates, Inc .

.*MPR 320 King Street Alexandria, VA 22314

  • Calculation No.

/Df-32.-0L Revision RECORD OF REVISIONS r-.

Prepared By r/~~

Description Page 2-

¢ Tri1n'4.l :r~svc..

---

  • mMPR. 320 King Street Alexandria, VA 22314 Calculation No. Prepared By Che~dr8r Page 3

/Df -0l. ~ r1S-C>0 1.0 PURPOSE The purpose of this calculation is to evaluate the possibility of fatigue cracks developing in ALCO 251 diesel engine cylinder liners due to mechanical loads.

2.0 RESULTS Several cases were evaluated: the nominal configuration along with several other cases to evaluate variations in key parameters. The table below summarizes the calculated alternating stresses and the mean-stress adjusted endurance limit for each case.

Mean Stress Alternating Goodman Diagram Eliptic Rule Case (ksi) Stress Endurance Limit Endurance Limit (ksi) (ksi) (ksi)

(j u =36

- (j u =42 (j u =36 (j u =42

  • Nominal 2 Mil Offset 8 Mil Offset 27.1 29.3 34.7 7.6 7.6 8.9 4.5 3.4 0.7 6.4 5.4 3.1 11.8 10.5 4.8 13.8 12.9 10.1 Worst Case 36.8 9.4 0 2.2 0 8.7 3.0 CALCUIATION The maximum stresses in the cylinder liner due to bolt preload forces and the engine firing pressure occur at the relief groove, at a location about 45° from the top of the groove. This location is shown in Figure 1. The stress intensity at this location was calculated in Reference 1 for several fit-up/tolerance cases (these cases are discussed in more detail in Reference 1):
  • Nominal - The nominal liner tolerances along with essentially no liner flange/engine blod misalignment.
  • 2 Mil Offset - The nominal liner tolerances along with 2 mils of misalignment between the liner flange and engine block.

320 King Street Alexandria, VA 22314 Calculation No. Prepared By Checked By

/o'i'-Jt..-o '-  ;..i__ t7,S.~ Page f-

MPR Associates, Inc.

[+]MPR 320 King Street Alexandria, VA 22314 Calculation No. Prepared By I of - 3i. -o '2- /Z-'L_

Page S

  • 8 Mil Offset - The nominal liner tolerances along with 8 mils of misalignment between the liner flange and engine block.
  • Worst Case - The worst case (from a stress point of view) tolerances along with the 8 mils misalignment.

Further, stresses were calculated for two conditions for each case: engine firing and not firing.

These two conditions represent the mechanical stress cycle for the liner.

The engine firing is a high cycle load (about 450 cycles per minute) so the mean stress endurance limit will be determined for comparison to the calculated stress intensities. From Reference 1, the calculated stress intensities are:

Case Maximum Stress Minimum Stress Alternating Stress Intensity Intensity Intensity (ksi) (ksi) (ksi)

  • Nominal 2 Mil Offset 8 Mil Offset 34.6 36.9 43.6 19.5 21.7 25.7 7.6 7.6 8.9 Worst Case 46.2 27.3 9.4 The maximum stress intensity occurs during liner/head fit-up; the minimum stress intensity occurs during engine firing. The alternating stress intensity is one-half the peak-to-peak range.

The endurance limit is a function of the mean stress intensity during the cycle. As the mean stress intensity increases, the endurance limit decreases. Two common methods for accounting for this effect are the Goodman Diagram and the Eliptic Rule. The Goodman Diagram is described by:

aa+am

_ _ =1 an au

. mMPR 320 King* Street Alexandria, VA 22314 Calculation No. Prepared By Checked By

/O! -32.-0L ,M- ,.--~ : / Q ~ Page ~

where aa is the endurance limit for a mean stress of am, an is the endurance limit with zero mean stress, and au is the material tensile strength...The Eliptic Rule is described by:

These relationships are shown graphically on the following page.

The specified material minimum tensile strength is 36 ksi (Reference 2). However, tensile tests show the tensile strength to be as high as 42 ksi. As a result, all calculations will be perfromed for both the 36 and 42 ksi values.

The zero mean stress endurance limit for cast iron varies depending on chemistry, strength and environment from about 15 to 22 ksi (it is typically about one-half the tensile strength). For the cylinder liners, an endurance limit of 18 ksi will be used (one-half the specified minimum tensile strength). Figure 2 shows a typical fatigue curve for-cast iron. This curve shows an endurance limit of about 20 ksi.

Using the above stresses and material properties, the mean stress adjusted endurance limits are calculated and are shown in Section 2.

MPR Associates, Inc.

mMPR 320 King Street Alexandria, VA 22314 Calculation No. Prepared By Checked By

of~3L.--o2-. A ~-~? Page 7
  • .-~~~~~---1.~~~~~~--1...~.:.......::=---~~~...L~~~_J

MPR Associates, Inc.

320 King Street Alexandria, VA 22314 Calculation No. Prepared By Checked By 8

~* s,LQ, Page

/Of-3t,-OL ~

0 Plain Iron 230

  • Alloy Iron. 1 % Ni. 0.4 % Cr.

220 0.6% Mo. 1.0% Mn 210 200 Ct]

a..

190 ~

180 ~

en Q)

(J)

~ 24 110 en en 160 22 150

  • 20 1QI 1{)I Cycles To Failure 1QT 140 130

- MPR Associates, Inc .

.mMPR* 320 King Street

  • Alexandria, VA 22314 Calculation No. Prepared By Checked BQy 0 c ---., Page a
  • 1----1o_r_-3_2_~_L____--L_ _ _ _ _ _ _ _ ~~----L-~~~*-~~=*~,,_.,,,~*::::::::~:.......L-------'--1

4.0 REFERENCES

1. MPR Calculation 108-32-01, "Finite Element Stress Analysis", 12/17/93.
2. Alco Power Co., Specification for Cast Iron Cylinder Liners.
3. Atlas of Fatigue Cuives, American Society for Metals, 1986.
Retrieved from "https://kanterella.com/w/index.php?title=ML18100A893&oldid=2505597"