Research on Low-Cycle Fatigue Engineered Hybrid Sandwich Ski Construction

Abstract

This research is aimed at evaluating the effect of low-cycle fatigue on a newly designed hybrid sandwich ski structure to determine the changes that may occur due to cyclic loading and thus affect its use. This is primarily concerned with the fatigue behavior of the tested ski over different time intervals simulating its seasonal use and its effect on the mechanical properties of the ski, i.e., the durability and integrity of the individual layers of the sandwich ski structure. The ski was subjected to 70,000 deflections by moving the crossbar by 60 mm according to the ski deflection calculation in the arch. The results of the cyclic tests of the engineered ski design showed no significant changes in the ski during loading. The average force required to achieve deflection in the first 10,000 cycles was 514.0 4.2 N. Thereafter, a secondary hardening of the structure occurred during relaxation and the force required increased slightly to 543.6 1.7 N. The required force fluctuated slightly during the measurements and in the last series the value was 540.4 0.8 N. Low-cycle fatigue did not have a significant effect on the mechanical properties of the ski; there was no change in shape or visual delamination of the individual layers of the structure. From the cross-section, local delamination was demonstrated by image analysis, especially between the Wood core and the composite layers E-Glass biaxial and Carbon triaxial.

Strain Measurement on the Glass-Fiber Reinforced Plastic by Using Optical Measurement System

“…Of course, skis are not made fully from FRP, in fact, skis are made as sandwich construction where FRP is just one of used materials in conjunction with metal and often carbon as well [14]. Skis can be made from even 15 layers of different materials [15]. In case of getting full field deformation, optical methods can be applied.…”