A Grain-Level Microstructure Model for Simulating of Crack Evolution Based on the CZM Method

2021 ◽  
pp. 1168-1177
Author(s):  
Zuoli Li ◽  
Qin Sun ◽  
Baoping Wang ◽  
Xiangzhen Kong
Keyword(s):  
Crack Evolution ◽  
Microstructure Model

Numerical calculation and stress analysis of crack evolution in coal with a central hole under nonuniform load

2017 ◽  
Vol 59 (9) ◽  
pp. 811-821
Author(s):  
Hongbao Zhao ◽  
Huan Zhang ◽  
Guilin Hu ◽  
Feihu Wang ◽  
Hongbing Wang
Keyword(s):  
Numerical Calculation ◽  
Stress Analysis ◽  
Central Hole ◽  
Crack Evolution ◽  
Nonuniform Load

scholarly journals A novel physics-based and data-supported microstructure model for part-scale simulation of laser powder bed fusion of Ti-6Al-4V

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Jonas Nitzler ◽  
Christoph Meier ◽  
Kei W. Müller ◽  
Wolfgang A. Wall ◽  
N. E. Hodge
Keyword(s):  
Selective Laser Melting ◽  
Microstructure Evolution ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Laser Melting ◽  
Cooling Rates ◽  
Powder Bed ◽  
Proposed Model ◽  
Microstructure Model ◽  
Transformation Diagrams

AbstractThe elasto-plastic material behavior, material strength and failure modes of metals fabricated by additive manufacturing technologies are significantly determined by the underlying process-specific microstructure evolution. In this work a novel physics-based and data-supported phenomenological microstructure model for Ti-6Al-4V is proposed that is suitable for the part-scale simulation of laser powder bed fusion processes. The model predicts spatially homogenized phase fractions of the most relevant microstructural species, namely the stable $$\beta $$ β -phase, the stable $$\alpha _{\text {s}}$$ α s -phase as well as the metastable Martensite $$\alpha _{\text {m}}$$ α m -phase, in a physically consistent manner. In particular, the modeled microstructure evolution, in form of diffusion-based and non-diffusional transformations, is a pure consequence of energy and mobility competitions among the different species, without the need for heuristic transformation criteria as often applied in existing models. The mathematically consistent formulation of the evolution equations in rate form renders the model suitable for the practically relevant scenario of temperature- or time-dependent diffusion coefficients, arbitrary temperature profiles, and multiple coexisting phases. Due to its physically motivated foundation, the proposed model requires only a minimal number of free parameters, which are determined in an inverse identification process considering a broad experimental data basis in form of time-temperature transformation diagrams. Subsequently, the predictive ability of the model is demonstrated by means of continuous cooling transformation diagrams, showing that experimentally observed characteristics such as critical cooling rates emerge naturally from the proposed microstructure model, instead of being enforced as heuristic transformation criteria. Eventually, the proposed model is exploited to predict the microstructure evolution for a realistic selective laser melting application scenario and for the cooling/quenching process of a Ti-6Al-4V cube of practically relevant size. Numerical results confirm experimental observations that Martensite is the dominating microstructure species in regimes of high cooling rates, e.g., due to highly localized heat sources or in near-surface domains, while a proper manipulation of the temperature field, e.g., by preheating the base-plate in selective laser melting, can suppress the formation of this metastable phase.

CT Image Analysis on the Meso-Damage of Construction Waste Recycled Brick

2012 ◽  
Vol 588-589 ◽  
pp. 1930-1933
Author(s):  
Guo Song Han ◽  
Hai Yan Yang ◽  
Xin Pei Jiang
Keyword(s):  
Fractal Dimension ◽  
Strain Curve ◽  
Ct Image ◽  
Stress Strain Curve ◽  
Crack Evolution ◽  
Construction Waste ◽  
Box Counting ◽  
Industrial Ct ◽  
Ct Image Analysis ◽  
Box Counting Method

Based on industrial CT technique, Meso-mechanical experiment was conducted on construction waste recycled brick to get the real-time CT image and stress-strain curve of brick during the loading process. Box counting method was used to calculate the fractal dimension of the inner pore transfixion and crack evolution. The results showed that lots of pore in the interfacial transition zone mainly resulted in the damage of the brick. With the increase of stress, the opening through-pore appeared and crack expanded, and the fractal dimension increased.

A stochastic microstructure model for particle reinforced aluminium matrix composites

2018 ◽  
Vol 273 (2) ◽  
pp. 115-126 ◽  
Author(s):  
K. LOSCH ◽  
S. SCHUFF ◽  
F. BALLE ◽  
T. BECK ◽  
C. REDENBACH
Keyword(s):  
Aluminium Matrix ◽  
Matrix Composites ◽  
Aluminium Matrix Composites ◽  
Microstructure Model

Ballistic penetration of conically cylindrical steel projectile into 3D orthogonal woven composite: a finite element study at microstructure level

2010 ◽  
Vol 45 (9) ◽  
pp. 965-987 ◽  
Author(s):  
Xiwen Jia ◽  
Baozhong Sun ◽  
Bohong Gu
Keyword(s):  
Finite Element ◽  
Impact Damage ◽  
Woven Composite ◽  
Strain Wave ◽  
Microstructure Model ◽  
Wave Distribution ◽  
Cylindrical Steel ◽  
3D Orthogonal Woven ◽  
The Impact ◽  
Ballistic Penetration

Ballistic penetration of conically cylindrical steel projectile into 3D orthogonal woven composite (3DOWC) was investigated from finite element analyses and ballistic impact tests. Based on the observation of the microstructure of the 3DOWC, a microstructure model was established for finite element calculation. In this model, the cross-section of warp, weft and Z-direction fiber tows was regarded as rectangular. The noninterwoven warp and weft yarns were bonded together with Z-yarns. The impact damage and energy absorption of the 3DOWC penetrated by a conically cylindrical steel projectile were calculated from the microstructure model and compared with the testing results. Good agreements with experiments have been observed, especially for deformation, damage evolution, and strain wave distribution in the 3DOWC under ballistic penetration.

scholarly journals Comparison of Local Load Influence on Crack Evolution of Coal and Briquette Coal Samples

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Hongbao Zhao ◽  
Tao Wang ◽  
Huan Zhang ◽  
Ziqiang Wei
Keyword(s):  
Crack Initiation ◽  
Crack Growth ◽  
Influencing Factor ◽  
Local Load ◽  
End Effect ◽  
Crack Evolution ◽  
Systematic Analysis ◽  
Effect Factor ◽  
Factors Influencing ◽  
Major Factors

Taking raw coal and briquette coal samples with preset center holes as research objects, this paper makes a systematic analysis and research of crack evolution laws of the two different coal samples under the local load. The results show that the raw coal and briquette coal samples are different mainly in number, dimension, and complexity of the internal microstructures, so it is not right to replace raw coal with briquette coal when performing observational study of the crack evolution of microstructures; under the effect of local load, local property, randomness of crack initiation position, and crack initiation stress of raw coal samples are greater than those of briquette coal samples; law of instantaneous maximum effective cut-through rate of raw coal samples is more complex than that of briquette coals; under the effect of uniformly distributed load, end effect factor Fe, sample microstructure influencing factor Fs, and preset center hole factor Fh are the major factors influencing crack growth, among which the amplified end effect factor Fe and sample microstructure influencing factor Fs are dominant factors; under the effect of local load, local load influencing factor Fp, end effect factor Fe, sample microstructure influencing factor Fs, and preset center hole factor Fs are the major factors influencing crack growth, among which the local load influencing factor Fp, end effect factor Fe, and sample microstructure influencing factor Fs are dominant factors. Compared with briquette coal samples, raw coal samples are more sensitive to influencing factors, such as local load influencing factor Fp, end effect factor Fe, sample microstructure influencing factor Fs, and preset center hole factor Fh, and can aggravate the influence of these factors on the crack growth; the paper also puts forward a method for describing local load based on a coupling mechanical model of uniaxial compression and local shear.

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