*Article* **Determination of the Parachute Harness Critical Load Based on Load Distribution into Individual Straps with Respect of the Skydiver's Body Position**

**Robert Grim \*, Robert Popela, Ivo Jebácek \*, Marek Hor ˇ ák and Jan Šplíchal**

Institute of Aerospace Engineering, Brno University of Technology, 60190 Brno, Czech Republic **\*** Correspondence: robert.grim@vutbr.cz (R.G.); jebacek@fme.vutbr.cz (I.J.)

**Abstract:** This article evaluates the redistribution of forces to the parachute harness during an opening shock load and also defines the ultimate limit load of the personal parachute harness by specifying the weakest construction element and its load capacity. The primary goal of this research was not only to detect the critical elements but also to gain an understanding of the force redistribution at various load levels, which could represent changes in body mass or aerodynamic properties of the parachute during the opening phase. To capture all the phenomena of the parachutist's body deceleration, this study also includes loading the body out of the steady descending position and asymmetrical cases. Thus, the result represents not only idealized loading but also realistic limit cases, such as asymmetric canopy inflation or system activation when the skydiver is in a non-standard position. The results revealed a significant difference in the strength utilization of the individual components. Specifically, the back webbing was found to carry a fractional load compared to the other webbing used in the design in most of the scenarios tested. Reaching the maximum allowable strength was first achieved in the asymmetric load test case, where the total force would be equal to the value of 7.963 kN, which corresponds to the maximum permissible strength of the carabiner on the measuring element three. In the same test case, the second weakest point would reach the limiting load force when the entire harness is loaded with 67.89 kN. This information and the subsequent analysis of the individual nodes provide a great opportunity for further strength and weight optimization of the design, without reducing the load capacity of the harness as a system. The findings of this study will be used for further testing and possible harness robustness optimization for both military and sport parachuting.

**Keywords:** parachute harness; opening load; limit load
