Answer
Rashin gajiya a maɓuɓɓugan ruwan raƙuman ruwa yakan fara farawa ne a ciki ko na waje gefuna na raƙuman igiyoyin igiyar ruwa inda damuwa mai ƙarfi ya fi girma. Karkashin lodin keken keke, iyakar damuwa $\sigma_r = \sigma_{max} - \sigma_{min}$ dole ne a kimanta shi daidai da Ma'aunin Goodman da aka Gyara. Idan damuwa da aka ƙididdige $ S = \ frac {3 \ cdot \ pi \ cdot P \ cdot D_m}{4 \ cdot b \ cdot t ^ 2 \ cdot N^2}$ ya wuce iyakar jimiri na abu (misali, kusan 30-40% na ƙarfin ƙugiya don 17-7PH), micro-cracks zai yadawa. Sau da yawa rashin ƙarfi yana ƙara haɓaka ta rashin lahani na sama kamar ramuka ko alamun kayan aiki daga aikin murɗawa. Don rage wannan, ana iya amfani da peening harbi don haifar da matsananciyar saura damuwa a saman, yadda ya kamata canza ma'anar damuwa zuwa ƙasa da tsawaita rayuwar gajiya daga $10^5$ zuwa sama da $10^6$ hawan keke.
