Aircraft Structures Review Concepts & Principles PDF

S T REN G T H O F M AT E R I A L Si s concerned with How dowe define S T REN G T H ?  Loads which depend on body volume are called Those loads which are produced by surface...

S T REN G T H O F M AT E R I A L Si s concerned with How dowe define S T REN G T H ?  Loads which depend on body volume are called Those loads which are produced by surface body loads. Examples are inertial, magnetic, contact. Examples are dynamic and/ or static and gravitational forces. Generally, these loads pressures. If the area of contact is very small, are assumed to be distributed over the entire then the load is said to be concentrated; volume of the body. otherwise, it is called a distributed load. Those loads that are time dependent, whereas Loads which are created on a restrained static loads are independent. structure by a uniform and/or non-uniform temperature change. R e g a r d l e s so f t h e c l a s s i f i ca t i o n s of the externall y imposed loads, a structural member, in general, resists loads i n t e r n a l l y. I t c a n b e a combination of the following loads. Axial + Shear Torsion + Bending Axial + Bending + Moment + Shear It isdefined as the s t re n g t h of a mat erial per unit a re a. T h ef o r c e t h a ta c t s perpendi cu l a r to the area. stress is said to be Normal stress when the direction of the deforming force is perpendicular to the cross-sectional area of the body. The length of the wire or the volume of the body changes stress will be at normal. T h ef o r c e parallel to t h ea r e a resisting thefo rce. Also known as tangential stress. I t i s t h ec o n t a c t p r e s s u r e b e t w e e n t h es eparate bodies. I t i s t h es t r e s s acting on a pipe w a l la l o n g t h el o n g i t u d i n a l d i r e c t i o n When two cross-sectional areas of the cylinder are subjected to equal and opposite forces the stress experienced by the cylinder is called longitudinal stress. A stress d i s t r i b u t i o nw i t h r o t a t i o n a ls y m m e t r y. Linear relation between elongation and the axial force. The limit beyond which the material will no longer go back to its original shape when the load is removed. The maximum stress that maybe developed such that there is no permanent or residual deformation when the load is entirely removed. The point at which the material will have an appreciable elongation without increase in load. The maximum ordinate in the stress-strain diagram. Also known as tensile strength. The strength of the material at rupture. Also known as breaking It states that the stress is directly proportional to strain. The proportionality constant on Hooke s Law. It is equal to the slope of the stress-strain diagram from O to P. It is the work done on a unit volume of a material as the force is gradually increased from O to P. It is the work done on a unit volume of a material as the force is gradually increased for O to R. The actual stress of a material under a given loading. The maximum safe stress The Ultimate Load is the Limit Load multiplied by a prescribed Safety Factor of 1.5. Any part of the structure of an aircraft must be able to support the Ultimate Load and, with certain exceptions, be able to do so without failure for at least 3 seconds the Limit Load is the maximum load to be expected in service. Any part of the structure of an aircraft must be able to support the limit load without permanent deformation.