Review of an Electrical Method for Evaluation of Stress Ratio Required to Cause Liquefaction and Dynamic Modulus

Based on shearing test, bending test in low temperature, fatigue test and dynamic modulus test, the text researched the effect on the property of the semi-flexible pavement by a kind of interfacial modifier. The study showed the feasible content of interfacial modifier was 0.4～0.6% . Used 0.4%, the shear strength reached 1.83MPa, flexural strength 6.97MPa, and fatigue-life was over 40000 at 0.2 stress ratio. From interfacial modification, the synthesis property of semi-flexible pavement was especially perfect.

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Accounting for the Frequency-Dependent Dynamic Modulus of Elasticity of Duralumin in Deformation Problems

Прикладная механика и техническая физика ◽

10.15372/pmtf20170317 ◽

2017 ◽

Keyword(s):

Modulus Of Elasticity ◽

Dynamic Modulus ◽

Frequency Dependent ◽

Dynamic Modulus Of Elasticity

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Damage accumulation near a hole under low cycle fatigue proceeding from measurements of local deformation response

Industrial laboratory Diagnostics of materials ◽

10.26896/1028-6861-2020-86-10-46-55 ◽

2020 ◽

Vol 86 (10) ◽

pp. 46-55

Author(s):

S. I. Eleonsky ◽

Yu. G. Matvienko ◽

V. S. Pisarev ◽

A. V. Chernov

Keyword(s):

Stress Intensity Factor ◽

Stress Intensity ◽

Intensity Factor ◽

Damage Accumulation ◽

Stress Ratio ◽

Low Cycle Fatigue ◽

Accumulation Process ◽

Stress Range ◽

Cycle Fatigue ◽

Deformation Response

A new destructive method for quantitative determination of the damage accumulation in the vicinity of a stress concentrator has been proposed and verified. Increase of damage degree in local area with a high level of the strain gradient was achieved through preliminary low-cycle pull-push loading of plane specimens with central open holes. The above procedure is performed for three programs at the same stress range (333.3 MPa) and different stress ratio values 0.33, – 0.66 and – 1.0, and vice versa for two programs at the same stress ratio – 0.33 and different stress range 333.3 and 233.3 MPa. This process offers a set of the objects to be considered with different degree of accumulated fatigue damages. The key point of the developed approach consists in the fact that plane specimens with open holes are tested under real operation conditions without a preliminary notching of the specimen initiating the fatigue crack growth. The measured parameters necessary for a quantitative description of the damage accumulation process were obtained by removing the local volume of the material in the form of a sequence of narrow notches at a constant level of external tensile stress. External load can be considered an amplifier enhancing a useful signal responsible for revealing the material damage. The notch is intended for assessing the level of fatigue damage, just as probe holes are used to release residual stress energy in the hole drilling method. Measurements of the deformation response caused by local removing of the material are carried out by electronic speckle-pattern interferometry at different stages of low-cycle fatigue. The transition from measured in-plane displacements to the values of the stress intensity factor (SIF) and the T-stress was carried out on the basis of the relations of linear fracture mechanics. It was shown that the normalized dependences of the stress intensity factor on the durability percentage for the first notch (constructed for four programs of cyclic loading with different parameters), reflect the effect of the stress ratio and stress range of the loading cycle on the rate of damage accumulation. The data were used to obtain the explicit form of the damage accumulation function that quantitatively describes damage accumulation process. The functions were constructed for different stress ratios and stress ranges.

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Nano Probe Analysis of Device Characteristics Affected by Ring Type Crystalline Defect

ISTFA 2011: Conference Proceedings from the 37th International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa2011p0322 ◽

2011 ◽

Author(s):

Jong Hak Lee ◽

Yu Jun Lee ◽

Jung Sam Kim ◽

Seo Kyung Jeong ◽

Min Su Kim ◽

...

Keyword(s):

Failure Analysis ◽

Physical Method ◽

Hybrid Analysis ◽

Electrical Method ◽

Ring Type ◽

Crystalline Defects ◽

Address Data ◽

Signal Input ◽

Crystalline Defect ◽

Top View

Abstract In this work, crystalline defects (dislocations) occurred in the silicon substrate during annealing SOD (Spin On Dielectric) which is an easy choice for its superior STI gap-fill ability. The reversal of address data that share same SIO (Signal Input Out) line in a DQ arises from crystalline defects. The failure analysis of physical methods has difficulty finding minute defects within the active because it is scarcely detectable from the top view. Situation can be well understood by electrical analysis using the nano probe. Due to its ability to probing contact nodes around the fail area, a ring type crystalline defect which is hardly detected from the top view was effectively analyzed by 3D TEM with the assistance of nano probe. This work shows that hybrid analysis of electrical method by nano probe and physical method by 3D TEM is useful and effective in failure analysis in semiconductor.

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ANALYSIS OF SOUND SPEED IN LONGITUDINAL DIRECTION AT REFERENCE MOISTURE CONTENT (w = 12 %) IN SAWMILL ASSORTMENTS (FAGUS SYLVATICA, L.)

Akustika ◽

10.36336/akustika20203745 ◽

2020 ◽

pp. 45-50

Author(s):

Alena Rohanová

Keyword(s):

Moisture Content ◽

Modulus Of Elasticity ◽

Dynamic Modulus ◽

Sound Speed ◽

Longitudinal Direction ◽

Structural Timber ◽

Sound Speeds ◽

Dynamic Modulus Of Elasticity ◽

Round Timber

This paper explores the analysis of sound speeds in the longitudinal direction and their reduction to the reference moisture content w = 12 %. The sound speed cw was determined with Sylvatest Duo device. Moisture content of beech sawmill assortments (round timber: N = 16, logs: N = 2 × 16, structural boards: N = 54) in the range of 12 – 72 % was measured. For the analysis purposes, the sound speed was converted to reference conditions (c12, uref = 12%). A second-degree polynomial (parabola) with a regression equation of the form: c// = 5649 - 27,371 × w + 0.0735 × w2 was used to convert cw to c12, and correction of measured and calculated values was used as well. The sound speeds c12 in sawmill assortments (c12,round, c12,log, c12,board) were evaluated by linear dependences. Dependence was not confirmed for c12,round and c12,board1 (r = 0.168), in contrast for c12,round and c12,log2 the dependence is statistically very significant (r = 0.634). The results of testing showed that the most suitable procedure for predicting quality of structural timber is the first step round timber – log2, the second step: log2 - board2. More exact results of the construction boards were obtained from log2 than from log1. The sound speed is used in the calculation of dynamic modulus of elasticity (Edyn). EN 408 mentions the possibility of using dynamic modulus of elasticity as an alternative method in predicting the quality of structural timber.

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