Epyura - the graphic scheme of the solution of a problem of study of the strength of materials when calculating strength characteristics and the operating loads of material. It reflects dependence of the bending moments on length of the loaded site of any element. It can be a beam or a farm, other bearing structure.
Instruction
1. When calculating durability of material it is considered that there are four types of internal efforts which arise in the elements loaded by external forces. It is the torque, cross force, longitudinal force and the bending moment.
2. Usually build epyura of the twisting and bending moments as the designs, most dangerous to strength characteristics. In need of studying distribution of longitudinal and cross forces on length of the loaded element, count and build also epyura of longitudinal Q and cross forces of N.
3. Epyura build in any scale and sign with the indication of dimension. It is obligatory for proportion to observe. The signs "+" and "-" in a circle are specified by the sign of an epyura on an epyura of forces.
4. Begin to build an epyura from the solution of tasks in theoretical mechanics and study of the strength of materials. Establish the nature of the considered element and type of its communications (ways of fixing in space). At the same time consider the following basic rules: - the system which is in rest is in balance; - the sum of forces operating on a balanced system is equal 0, also as well as the sum of the moments created by these forces; - the moment - the work of force on a shoulder, distance perpendicular to force from a point of application of force to a moment point; - force directed up - is positive, directed down – is negative; - if the system at the application of the moment to seek to turn clockwise – a good point if against – negative.
5. Specify the exact true direction of reactions of communication of the considered elements. For this purpose define dependences of force and the moment on an argument x and also the direction of the course (from right to left or on the contrary).
6. Take a pencil, a ruler, paper. Draw with observance of scale the schematical image of the considered element (core) and its connections (support).
7. According to calculations specify points of application and the directions of forces, their size. Specify a point of application of the moment, its direction.
8. Break an element into sites (sections), specify in them cross forces, construct for them epyura. Define the bending moments in sections. Construct epyura of the bending moments.