Author
J.W. Ju
Other affiliations: Woosuk University, Princeton University, KAIST ...read more
Bio: J.W. Ju is an academic researcher from University of California, Los Angeles. The author has contributed to research in topics: Micromechanics & Plane stress. The author has an hindex of 15, co-authored 18 publications receiving 3493 citations. Previous affiliations of J.W. Ju include Woosuk University & Princeton University.
Papers
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TL;DR: In this article, a dual framework for elastic cap damage was proposed, where a strain-and a stress-based approach was employed, and a viscous regularization of strain-based, rate-independent damage models was also developed.
1,158 citations
TL;DR: In this paper, an energy-based coupled elastoplastic damage theory for ductile and brittle materials is presented, which employs irreversible thermodynamics and internal state variable theory for damage.
865 citations
TL;DR: In this paper, a viscous regularization of strain-based, rate-independent damage models is also developed, with a structure analogous to viscoplasticity of the Perzyna type, which produces retardation of microcrack growth at higher strain rates.
377 citations
TL;DR: In this paper, the authors developed continuum isotropic and anisotropic elastoplastic-damage models, formulated either in strain space on the basis of the effective stress concept, or in stress space and employing the dual notion of effective strain.
314 citations
TL;DR: In this paper, the effects of lowering pH by an acidulant (citric acid) on the formation of acrylamide in fried and baked corn chips and in french fries were studied by using a GC/MS.
Abstract: The effects of lowering pH by an acidulant (citric acid) on the formation of acrylamide in fried and baked corn chips and in french fries were studied by using a GC/MS. The 0.2% citric acid treatments induced 82.2% and 72.8% inhibition of acrylamide formation in fried and baked corn chips, respectively. Dipping potato cuts in 1% and 2% citric acid solutions for 1 h before frying showed 73.1% and 79.7% inhibition of acrylamide formation in french fries. In the experiment of heating 1 mL solution containing asparagine and glucose in phosphate buffers, by lowering the pH from 7.0 to 4.0, 99.1% inhibition of acrylamide formation was achieved. This is the first finding of an effective, simple, and practical way to limit the acrylamide formation in real foods.
258 citations
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TL;DR: In this article, a constitutive model based on an internal variable-formulation of plasticity theory for the non-linear analysis of concrete is presented, which uses a new yield criterion which matches experimental data quite well and it accounts for both elastic and plastic stiffness degradations effects.
3,080 citations
TL;DR: In this paper, a new plastic-damage model for concrete subjected to cyclic loading is developed using the concepts of fracture-energy-based damage and stiffness degradation in continuum damage mechanics.
Abstract: A new plastic-damage model for concrete subjected to cyclic loading is developed using the concepts of fracture-energy-based damage and stiffness degradation in continuum damage mechanics. Two damage variables, one for tensile damage and the other for compressive damage, and a yield function with multiple-hardening variables are introduced to account for different damage states. The uniaxial strength functions are factored into two parts, corresponding to the effective stress and the degradation of elastic stiffness. The constitutive relations for elastoplastic responses are decoupled from the degradation damage response, which provides advantages in the numerical implementation. In the present model, the strength function for the effective stress is used to control the evolution of the yield surface, so that calibration with experimental results is convenient. A simple and thermodynamically consistent scalar degradation model is introduced to simulate the effect of damage on elastic stiffness and its recovery during crack opening and closing. The performance of the plastic-damage model is demonstrated with several numerical examples of simulating monotonically and cyclically loaded concrete specimens.
2,825 citations
2,140 citations
TL;DR: In this article, a consistent numerical solution procedure of the governing partial differential equations is presented, which is shown to be capable of properly simulating localization phenomena, and the introduction of higher-order deformation gradients in the constitutive model is demonstrated to be an adequate remedy to this deficiency of standard damage models.
Abstract: SUMMARY Conventional continuum damage descriptions of material degeneration suffer from loss of well-posedness beyond a certain level of accumulated damage. As a consequence, numerical solutions are obtained which are unacceptable from a physical point of view. The introduction of higher-order deformation gradients in the constitutive model is demonstrated to be an adequate remedy to this deficiency of standard damage models. A consistent numerical solution procedure of the governing partial differential equations is presented, which is shown to be capable of properly simulating localization phenomena.
1,207 citations
TL;DR: In this paper, a constitutive model for anisotropic damage is developed to describe the elastic-brittle behavior of fiber-reinforced composites and the corresponding rate-equations are subjected to the laws of thermomechanics.
1,099 citations