Numerical simulation of ram extrusion in short-fiber-reinforced fresh cementitious composites

Abstract

A series of ram extrusion tests was carried out on a short-fiber-reinforced, semisolid, fresh cementitious composite. An elastoviscoplastic constitutive model is proposed for the extrudable fresh cementitious composite. It features the associative flow rule, a nonlinear strain rate-hardening law, and the von Mises yield criterion. The model is then implemented in ANSYS/LS-DYNA explicit finite element code.Various ram extrusion processes of the fresh cementitious composite were simulated. It has been found that the extrusion load versus imposed displacement predictions agree well with the experimental results. The fresh paste flow, through the die entry and the die-land, is then interpreted in light of the evolution of the deformation and distribution of state variables, mainly based on numerical results and the ram extrusion mechanism.The effects of extrusion ratio and extrusion velocity on extrusion load are also investigated, based on the mechanical properties of the fresh cementitious composite. The study indicates that the numerical procedure established, together with the constitutive model proposed, is applicable for describing ram extrusion of short-fiber-reinforced fresh cementitious composites, which might provide a numerical rheometric tool from which ram extrusion of elastoviscoplastic paste-like materials can be examined and quantified.

Manufacturing cement-based materials and building products via extrusion: from laboratory to factory

“…The constitutive model was successfully employed in simulating the monotonic upsetting process (Zhou and Li, 2007) and the ram extrusion process (Zhou and Li, 2009) of semi-solid, dough-like fibre-reinforced fresh cement-based materials tailored for extrusion. On the other hand, Perrot et al (2009) proposed linking the rheological concepts of firm cement-based materials and soil mechanics and established a simple criterion to predict the extrusion ability of a mortar.…”

A rheological constitutive model for semiconcentrated rod suspensions in Bingham fluids

“…16 Fiber orientation has been improved in the pipe extrusion process, 17 which has been applied to the fabrication of concrete pipes reinforced with steel fibers. 18 Zhou and Li 19 used the ram extrusion to study fiber reinforced cementitious materials. In their work, a numerical simulation using the Herschel-Bulkley model was developed to model the process.…”

Rheology of semi-solid fresh cement pastes and mortars in orifice extrusion

“…This constitutive model is based on the consistency viscoplasticity [23] and features the von-Mises yield criterion, the associated flow rule and nonlinear strain rate-hardening law with the Herschel-Bulkley relationship between the flow stress and strain rate. The rate-form constitutive model is integrated into an incremental formulation which enables it to be implemented into numerical frameworks, like finite element formulation [11,24]. For each of the physical phenomena included in the elasto-viscoplastic constitutive model, one or more material parameters are required, which need to be determined from those 'non-traditional' test methods, i.e., capillary extrusion, upsetting, squeezing flow etc., described above plus appropriate experimental data interpretation techniques.…”