Autoclave processing is a commonly used state-of-the-art fiber-reinforced composite manufacturing technology, albeit with high capital cost, long cycle times and high energy consumption. Alternatively, out-of-autoclave processing reduces the initial and operating costs while producing composite structures with similar quality as that of autoclave parts. Additive Manufacturing (AM) the scaled-up molds for out-of-autoclave process using carbon fiber (CF) reinforced composite offers design flexibility, enhanced mechanical, and thermal properties in addition to reduction in weight and cost. However, heating of these molds using an oven is still expensive and necessitates an energy-efficient heating process. In this study, resistive heating through heating elements embedded within fiber reinforced composite molds is used as an efficient heating mechanism. The goal is to design wire embeddings and determine the optimal heat flux density to achieve a target uniform temperature of 80°C across the mold surface. To this end, numerical analyses were performed to evaluate the temperature distribution across the composite mold surface for a given wire placement and mold configuration. Constant thermal properties of the 20 wt.% short CF reinforced acrylonitrile butadiene styrene (ABS) were used in the thermal analysis. Time taken to reach the steady state temperature was also estimated. Design guidelines for wire embeddings were included to enable efficient manufacturing of fiber-reinforced composites through out-of-autoclave molds.
With the advent of additive manufacturing, lattice structures have been of increasing interest for engineering applications involving light‐weighting and energy absorption. Several studies have investigated mechanical properties of various lattices made up of mostly unreinforced polymers and lack numerical analysis for reinforced lattice structures. In this paper, mechanical response of short fiber reinforced lattice structures under compression is investigated through experiments and numerical simulations. Three different 2D lattices namely, square grid, honeycomb, and isogrid along with their rotated counterparts were fabricated using 15% wt carbon fiber‐acrylonitrile butadiene styrene and experimentally evaluated through uniaxial compression testing up to 30% strain. As simulations on fiber‐reinforced lattices under large compressive strains are rarely performed and published, finite element models accounting for fiber orientation induced anisotropic mechanical properties and geometrical imperfections were developed to predict the stress–strain characteristics up to 30% compressive strains. The stress–strain curves predicted from the numerical simulations matches well with the experimental responses for various lattice geometries. Various failure mechanisms such as thin strut buckling, contact within the lattice, and fracture of struts under large deformation were investigated. Analyzing energy absorption characteristics of these lattices revealed that the honeycomb structures in horizontal configuration exhibits superior energy absorption capability.
The mechanical response of a heterogeneous medium results from the interactions of mechanisms spanning several length scales. The computational homogenization method captures direct influence of underlying constituents and morphology with a numerically efficient framework. This study reviews the performance of first order computational homogenization technique with a flat punch indentation problem. Results obtained are benchmarked against those using direct numerical simulations (DNS) with full microstructural details. It is shown that the computational homogenization method is able to capture structural response adequately, even for constituent materials with nonlinear behavior. However, the first order computational homogenization method becomes problematic when localized macroscopic deformation occurs. In this context, some re- cent trends addressing the issues are discussed.
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