Fracto-Emission from Interfacial Failure

1989 ◽  
Vol 153 ◽  
Author(s):  
J. T. Dickinson
Keyword(s):  
Crack Growth ◽  
Excited States ◽  
Charge Separation ◽  
Failure Modes ◽  
Ground States ◽  
Dissimilar Materials ◽  
Interfacial Failure ◽  
Neutral Species ◽  
Positive Ions ◽  
Fracture Of Materials

AbstractFracto-Emission is the emission of particles and photons during and after fracture of materials. The observed emission includes electrons, negative and positive ions, neutral species in both ground states and in excited states, and visible photons. This emission can often serve as a sensitive probe of crack growth and may prove to be a useful tool for investigating molecular and microscopic events accompanying crack growth and for studying the details of failure modes in a variety of materials. Interfacial failure provides unique fracto-emission signals due to the extensive charge separation accompanying separation of dissimilar materials. Here we present the results of several recent studies of interfacial failure involving a variety of materials and relate them to electronic and mechanical processes accompanying failure.

Electronic Structure of the Transition Elements

1973 ◽  
Vol 51 (6) ◽  
pp. 644-647
Author(s):  
K. M. S. Saxena ◽  
S. Fraga
Keyword(s):  
Electronic Structure ◽  
Excited States ◽  
Ground State ◽  
Ground States ◽  
Negative Ions ◽  
State Function ◽  
Transition Elements ◽  
Hartree Fock ◽  
Positive Ions ◽  
Single Set

Numerical Hartree–Fock functions have been determined for the ground states and first excited states of the configurations 3dN4s0 and 3dN4s2 for the negative ions, neutral atoms, and first four positive ions of all the transition elements. The validity of the approximation, embodied in the use of a single set of parameters determined from the ground state function of a configuration for the prediction of the spectroscopic levels arising from it, has been examined in detail in the case of Fe I, 3d64s2, where independent calculations have been carried out for all the excited states.

scholarly journals Effect of weld nugget size on failure mode and mechanical properties of microscale resistance spot welds on Ti–1Al–1Mn ultrathin foils

2018 ◽  
Vol 10 (7) ◽  
pp. 168781401878528 ◽  
Author(s):  
Feng Chen ◽  
Shiding Sun ◽  
Zhenwu Ma ◽  
GQ Tong ◽  
Xiang Huang
Keyword(s):  
Mechanical Properties ◽  
Failure Mode ◽  
Failure Modes ◽  
Mechanical Performance ◽  
Weld Nugget ◽  
Interfacial Failure ◽  
Spot Welds ◽  
Resistance Spot ◽  
Resistance Spot Welds ◽  
Pullout Failure

We use tensile–shear tests to investigate the failure modes of Ti–1Al–1Mn microscale resistance spot welds and to determine how the failure mode affects the microstructure, microhardness profile, and mechanical performance. Two different failure modes were revealed: interfacial failure mode and pullout failure mode. The welds that fail by pullout failure mode have much better mechanical properties than those that fail by interfacial failure mode. The results show that weld nugget size is also a principal factor that determines the failure mode of microscale resistance spot welds. A minimum weld nugget size exists above which all specimens fail by pullout failure mode. However, the critical weld nugget sizes calculated using the existing recommendations are not consistent with the present experimental results. We propose instead a modified model based on distortion energy theory to ensure pullout failure. Calculating the critical weld nugget size using this model provides results that are consistent with the experimental data to high accuracy.

Extent of charge separation in suddenly polarized twisted excited states of linear polyenes

1977 ◽  
Vol 99 (11) ◽  
pp. 3587-3596 ◽  
Author(s):  
M. C. Bruni ◽  
J. P. Daudey ◽  
J. Langlet ◽  
J. P. Malrieu ◽  
F. Momicchioli
Keyword(s):  
Excited States ◽  
Charge Separation ◽  
Linear Polyenes

scholarly journals A Quality Study of a Self-Piercing Riveted Joint between Vibration-Damping Aluminum Alloy and Dissimilar Materials

2020 ◽  
Vol 10 (17) ◽  
pp. 5947
Author(s):  
Dong Hyuck Kam ◽  
Taek Eon Jeong ◽  
Jedo Kim
Keyword(s):  
Aluminum Alloy ◽  
Failure Modes ◽  
Mechanical Performance ◽  
Dissimilar Materials ◽  
Vibration Damping ◽  
Shear Load ◽  
Load Testing ◽  
Tensile Shear ◽  
Reinforced Plastic ◽  
Riveted Joints

This study investigates the quality of self-piercing riveted joints between vibration-damping aluminum (Al) and other dissimilar materials, namely aluminum alloy (AL5052-H32), steel alloy (GA590DP), and carbon-reinforced plastic (CFRP). The effects of die types (flat, cone, and nipple) on the geometrical characteristics and mechanical performance of the joints are studied using a cross-section examination and tensile shear load testing. The failure modes of each joint are also presented, showing the nature of the forces leading to the joint failures. The results indicate that, for all configurations, adequate joining between vibration-damping Al with AL5052-H32 is expected with a maximum shear load up to 3.28 kN. A shear load up to 3.6 kN was measured for the joints with GA590DP panels with acceptable top and bottom seal characteristics. A vibration-damping Al panel can only be positioned at the bottom when riveting with CFRP due to the brittle nature of CFRP. A tensile shear load up to 2.26 kN was found, which is the lowest amongst the materials tested in this study.

Solvent Induced Charge Separation in the Excited States of Symmetrical Ethylene:  A Direct Reaction Field Study

2001 ◽  
Vol 105 (14) ◽  
pp. 3583-3590 ◽  
Author(s):  
Robert W. J. Zijlstra ◽  
Ferdinand C. Grozema ◽  
Marcel Swart ◽  
Ben L. Feringa ◽  
Piet Th. van Duijnen
Keyword(s):  
Field Study ◽  
Excited States ◽  
Charge Separation ◽  
Direct Reaction ◽  
Reaction Field ◽  
Induced Charge

Exceptional case of Kasha's rule: Emission from higher-lying singlet electron excited states into ground states in coumarin-based biothiol sensing

2018 ◽  
Vol 152 ◽  
pp. 118-126 ◽  
Author(s):  
Nguyen Khoa Hien ◽  
Doan Thanh Nhan ◽  
Won Young Kim ◽  
Mai Van Bay ◽  
Pham Cam Nam ◽  
...  
Keyword(s):  
Excited States ◽  
Ground States ◽  
Exceptional Case ◽  
Electron Excited States

scholarly journals Dynamic Behavior of Self-Piercing Riveted and Mechanical Clinched Joints of Dissimilar Materials: An Experimental Comparative Investigation

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Yulong Ge ◽  
Yong Xia
Keyword(s):  
Mechanical Behavior ◽  
Failure Modes ◽  
Dissimilar Materials ◽  
Dynamic Effect ◽  
Comparative Investigation ◽  
Rate Dependent ◽  
Lap Shear ◽  
Baking Process ◽  
Before And After ◽  
Peel Tests

The present work compares the dynamic effect of a self-piercing riveted (SPR) joint with that of a mechanical clinched joint having the dissimilar materials combination. The substrates used in this investigation are aluminum alloy AA5182-O and deep drawing steel DX51D+Z. The static and dynamic behaviors and the failure modes of the SPR and clinching joints are characterized by lap-shear, cross-tension, and coach-peel tests. The influence of the strain-rate-dependent mechanical behavior of the substrates on the joints is examined; this can help improve prediction of the energy absorption of the joints under impact loading. Considering the realistic baking process in a painting shop, the deforming and hardening effects on the SPR and the clinched joints induced by baking are also studied. The specimens are heated to 180°C for 30 min in an oven and then cooled down in air. The SPR and the clinched joints before and after the baking process are compared in terms of the mechanical behavior.

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