Numerous researches on determination of coefficients of friction of single copies of some species of fish on the materials which are the most often used for production of working bodies of fish-processing cars were conducted.
The necessary number of experiments can be defined as follows. At first to make five-six experiments and to calculate a confidential interval, and then to specify necessary number of measurements, recognizing that reduction of a confidential interval in λ time provides increase in number of measurements in λ 2 times.
Rheological properties of real bodies can be characterized by elasticity, viscosity and plasticity. At the description of rheological properties of a body of fish also other terms, such as tension, deformation, a relaxation and t will be used.
Record of process of friction can be carried out if as the measuring device to use an elastic element with small rigidity and to fix directly movement of an elastic element or to choose an elastic element of considerable rigidity and its deformation to write down by means of strain gages, the amplifier and a shleyfovy oscillograph. Record of process of friction by means of strain gages is the most acceptable as it is possible to change sensitivity of strain gages in the wide range by means of a tenzousilitel.
Proceeding from the standard requirements, the design of experimental installation for research of coefficients of friction of fishes has to be as it is possible more simply and at the same time to guarantee sufficient reliability of the received results.
Process of deformation of a real body is very difficult, therefore difficultly to construct mathematical model of such body even in the presence of empirical coefficients. Actually the model has to describe such properties as elastic deformation, a plastic and viscous current, creep and a relaxation etc. If even it was succeeded to create such model, it would be too bulky to form a basis for the solution of the tasks connected with determination of tension and deformations in solid bodies. In this regard usually use simpler models describing only those mechanical properties which are most essential to the considered task.
Relaxation of tension — this reduction of tension in a body at continuous deformation. Thus it is supposed that deformation is created with a high speed, otherwise the relaxation of tension can pass partially completely pl during deformation creation.
Kinetic coefficients of friction of fishes can be investigated on the special installations described below. The first two are similar to the installations applied to research of static friction. On these installations it is possible to investigate kinetic coefficients of friction at small speeds of sliding. At speeds of sliding over 0,1 m/s it is impossible to execute the corresponding researches as sliding plane length practically does not exceed 1 m and for so short period of time frictional contact does not manage to be created, and, therefore, friction force of sliding will be a variable.
For transportation of the fish frozen in briquettes on the inclined planes and by means of conveyors it is necessary to know tilt angles at which such transportation is possible. Tilt angles can be defined if friction are known you
Installations of two types are most often applied to research of coefficients of static friction: installations in which fish, and installations in which the studied surface moves moves. It is necessary for research of kinetic coefficients of friction that the speed of relative movement of fish changed in the wide range.
Usually understand as deformation not only the process of relative movement of points of a body proceeding in time, on and instant moving of points of a body to any fixed timepoint during: this process.
Straight-line and morphometric characteristics of fishes, and also coordinates of the center of gravity and density of fishes are necessary data for designing of the fish-processing equipment and can be used for optimization of technological processes.
Were engaged in definition of straight-line and morphometric characteristics of fishes practically all basin research institutes and some design offices, however are not present a uniform technique of processing of experimental data.