Predicting Steel Fiber Distribution in Fresh Concrete Using DEM

Predicting Steel Fiber Distribution in Fresh Concrete Using DEM–SPH

- December 3, 2025 at 7:24 pm
  
  mahdi.ben-ftima
  Subscriber
  
  Hello,
  
  Hello, I have been working for over a year with the Rocky software and its DEM–SPH functionality on the modeling of the flow of fluid concrete containing steel fibers. This type of modeling is quite complex and makes it possible to estimate the local orientation and distribution of the steel fibers during casting. This information is critically important for accurately modeling the mechanical behavior of the concrete once it has hardened. In my view, this type of numerical approach is key to enabling the transition from an empirical fiber-reinforced concrete to a controlled, certifiable, and fully industrializable material.
  All simulations in my study were performed using Rocky 2023, in which no limitation was imposed on the SPH particle size to DEM particle size ratio. I conducted a numerical benchmark in the paper, which shows that for slender DEM particles such as fibers (slenderness ratio larger than 15), reliable results can be obtained for SPH-to-fiber diameter ratios (SPH/df) between 0.5 and 0.6.
  I was therefore surprised to learn that, starting in Rocky 2024, a new restriction has been introduced whereby the software no longer allows simulations for SPH/df ratios greater than 0.4. This limitation would make all my current analyses infeasible and, more broadly, would seriously jeopardize the use of Rocky for fiber-reinforced concrete applications. A quick assessment indicates that a typical slab flow simulation would increase from 4 days to 25 days of computation time, and from 80 GB to more than 140 GB of GPU memory, effectively making the tool unusable in my research context.
  Would it be possible to consider, in an upcoming 2025 R2 version (beta or official), an option to lift this hard limitation and instead simply provide a warning message when ratios above 0.4 are used? This issue is critical for my ongoing and future work.
  I apologize for the length of this request and thank you in advance for your time and consideration. I sincerely look forward to your feedback.