Real-time self-monitoring properties in 3D printed continuous carbon fiber reinforced thin-walled composite structures under large deformation

Deformation monitoring is a crucial approach to ensuring safety and reliability of thin-walled structures. In this study, an electrical-resistance-based deformation monitoring method was utilized for real-time structural health monitoring of 3D printed continuous carbon fiber reinforced thin-walled composite structures. The correlation between deformation and electrical resistance changes was investigated in quasi-static lateral and axial compression for the composite structures with three different layer heights. Results showed that the mechanical–electrical behaviors during lateral and axial compression processes manifested distinct forms. A bilinear relationship between relative resistance change and compression displacement during lateral compression was obtained. Furthermore, the composite structures with lower layer heights demonstrated a higher linear correlation coefficient. Under axial compression, the relative resistance change showed a fluctuating fall/rise pattern. This pattern was associated with intricate damage morphology observed in the composite structures, such as fiber-to-fiber contact, fiber breakage, and fiber pull-out. In addition, the relative resistance change demonstrated a falling-rising pattern in the composite structures with a layer height of 0.3 mm, while it exhibited a falling-rising-falling pattern with other layer heights. The established correlation between the relative resistance change and deformation could facilitate real-time self-monitoring of deformation and failure states in thin-walled structures

Modeling the large inelastic deformation response of non-filled and silica filled SL5170 cured resin

In recent years, important efforts have been focused on rapid production of tools using Rapid Prototyping and Manufacturing (RP&M) technologies such as the Stereo-Lithography Apparatus (SLA). One of the applications is the development of rapid polymer tooling such as dies for injection molding. For these applications, optimal thermal as well as mechanical properties of final tools are of significance. In order to characterize the mechanical response of materials made by SLA, a standard set of material tests, including uniaxial tension and compression tests under different strain rates and different temperatures, was conducted for both silica filled and non-filled resin. In this paper, the mechanical response of the non-filled SL5170 cured resin is discussed in terms of an elastic-viscoplastic material model. Further, a new model for silica filled SL5170 cured resin was developed to estimate the stress-strain relationship of the composite. This composite model is an extension of the elastic-viscoplastic model for non-filled resin to include the elastic deformation of the silica particles. The stress-strain curves predicted by the models under homogeneous deformation show good agreement with the experimental results.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44781/1/10853_2005_Article_903.pd

Simulation of the stretch blow moulding process: from the modelling of the microstructure evolution to the end-use elastic properties of polyethylene terephthalate bottles

The original publication is available at www.springerlink.comThe whole stretch blow-moulding process of PET bottles is simulated at the usual process temperature in order to predict the elastic end-use properties of the bottles. An anisotropic viscoplastic constitutive law, coupled with microscopic variables, is dentified from uniaxial tensile tests performed at different strain rates and temperatures. The microstructure evolution is characterised by crystallinity measurements from interrupted tests and frozen samples. For each specimen tested, the Young modulus is measured at room temperature. Numerical simulations of the blow moulding process are run using the C-NEM method. A micromechanical modelling is post-processed after the simulation to predict the elastic properties. Predictions of Young modulus distributions in bottles are in agreement with the ones measured on blow-moulded bottles

Modeling of dynamic failure by nucleation and growth processes

It is well established that high rate failure of structural materials takes place by rate processes occurring at the micro level and involving nucleation, growth, and coalescence of voids or cracks. At the submicroscopic level, the mechanism of failure in materials is dislocation controlled. The process of deformation and failure can be described by plastic glide that involves the mechanism of dislocation pile-ups. A new physically based model describing these processes is proposed. The effects of inertia and rate sensitivity on the growth process, and porosity are examined. The model formulation is three-dimensional and is suitable for a general state of stress and strain. The model constants are calibrated through numerical simulations of one dimensional strain based plate impact experiments. To demonstrate the generality of model to predict spall under multiaxial loading conditions, an experimental configuration in which a flyer plate impacts the base of a solid right circular cone has been simulated. The computational modeling has been performed with thermomechanical coupling. The mechanical threshold stress plasticity model, the new proposed failure model, and the equation of heat conduction have been implemented in the finite element code Abaqus. Results from these simulations are presented and discussed in comparison with the experimental results. This shows the capability of the model in matching the experimentally observed spall patterns in the solid cone

A new intermediate model for polycristalline viscoplastic deformation and texture evolution.

International audienc

Rolling texture transition in FCC metals using the viscoplastic φ -model and considering mechanical twinning

The viscoplastic Φ-model belongs to the same class of self-consistent models but it is based on a new theory without the Eshelby scheme. The Φ-model, by varying the parameter Φ, can predict a very large range of the texture components: from the lower (Φ →1) to the upper (Φ→0 ) bounds results. In this work, we adapt the Φ-model to take into account the mechanical twinning. This extended Φ-model is used to predict textures in FCC metals under plane strain compression test. We show that the deformation twinning plays an important role in the formation of brass-type texture