Automatic Welding, 2017, №02



2017 №02 (07)

DOI of Article 10.15407/as2017.02.08

2017 №02 (09)

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Avtomaticheskaya Svarka (Automatic Welding), #2, 2017, pp. 41-48
 

Effect of vibrotreatment on fatigue resistance and damping capacity of structural elements with residual stresses

V.A. Degtyarev

G.S. Pisarenko Institute for Problems of Strength, NASU 2 Timiryazevskaya Str., , 01014, Kiev, Ukraine. E-mail: ips@ipp.kiev.ua
 
Abstract
A work, based on a complex diagram of cycle limit stresses, proposes a method for selection of vibrotreatment undamaging modes for the elements of metal structures in order to gain effective decrease of their residual stresses without a risk of fatigue damage during technological treatment. This method was approved by the example of testing of the structural elements of steel 20 and end pivot of steel 20GFL of span bolster of eight-axis rail tank car. Comparative fatigue tests showed 2.5 times increase of fatigue life of treated welded specimens and rise of their endurance limit by 40 %. In process of vibrotreatment of a circular element of steel St.3, decrease of residual stresses is accompanied by rise of its damping capacity. Growth of maximum cycle stresses promotes for increase of vibration decrement to larger value and its stabilizing in time matches with residual stress stabilizing. This allows assessing completion of a process of change and further stabilizing of the vibration decrement. Determined decrease of damping capability of the investigated sample after vibrotreatment indicates its strain aging, showing plastic strain during treatment. Rise of cycle stress amplitude reduces sample deformation after vibrotreatment at further aging to 1500 h and decrease of initial residual tensile stresses to 0.51 of yield limit of the material results in its geometry stability. 25 Ref., 2 Tables, 7 Figures.
 
Keywords: vibrotreatment, welded joint, residual stresses, endurance limit, cycle stress amplitude, cyclic creep limit, vibration decrement
 
 
Received: 07.12.16
Published: 16.03.17
 
 
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