Portable strain and fatigue measuring kit

Parallel to Hullmos, HMC developed the Marine Quality Kit (MQK) together with TNO as a portable strain and fatigue measuring system. Where Hullmos is installed on a ship to serve the ships lifetime, the MQK is easily installable and removable on any given structure. The MQK is designed to measure strain and calculate fatigue life of structures like seafastening or project cargo, to give insight in the fatigue damage over a given period of time.

When a heavy transport object is shipped by sea, irregular cyclic loads will act on this object. In some cases these loads will cause fatigue damage. Little is known with respect to the actual level of fatigue damage sustained during a transport. In order to quantify the fatigue damage, a gauging system has been developed which can be mounted at a location on the object which is expected to be sensitive to fatigue. The system records the strains in the gauges as time traces. Moreover the system calculates a rate of fatigue and the fatigue accumulation during the voyage.

When a structure is subjected to a cyclic mechanical load, cyclic stresses occur in that structure. Even when these stresses are well below the yield stress of the material used, the structure may lose integrity after a (large) number of cycles. An integrity loss shows as material cracking in areas where high stresses occur. This type of damage is called fatigue damage.

With the MQK HMC developed a very useful tool for reducing fatigue damage to cargoes. The system is a practical decision support system to assist the crew of the vessel to undertake actions to reduce fatigue. Changing course or speed will immediately result in a change in the cumulative fatigue indicator on the bridge.

The MQK consists of 4 strain sensors, HMC and TNO software, and all required auxiliary equipment to work in the typical harsh offshore environment.