Hydraulic Substitute Base for Demolition Hammers

Demolition hammers are currently tested on mineral materials or on mechanical substitute base systems such as the steel ball energy absorber Dynaload. These bases are either destroyed during testing or not designed to replicate different materials. This work investigates a hydraulic substitute base as an equivalently effective, repeatable, adjustable, and low-wear alternative. Various arrangement concepts are evaluated. The selected concept combines a tool of a demolition hammer and a cylinder piston into a single impact body. The design approach uses a co-simulation that couples an FEM model of the impact mechanism with a hydraulic base model. Parameter studies show that by tuning hydraulic capacitance, resistance, and inductance, the tool displacement curves and dissipated energy can be targeted to approximate real materials. Therefore, this paper shows how a hydraulic substitute base could be adjusted. For concrete-like behavior (penetration depth ≈ 0.4 mm, energy absorption ≈ 83%), the simulation yields a required volume of 0.3 ml with mineral oil and an orifice cross-section of about 1.1 mm². With the identified adjustment ranges for capacitance and resistance, a hydraulic substitute base for a handheld rotary hammer with 4.2 J impact energy can be designed. ... mehrThe methodology can be transferred to other impact demolition hammers, such as hydraulic breakers, enabling reproducible testing.