Load and Stress Analysis Flashcards
__________ come across different materials like
cement, concrete, steel and others which are used
to complete the project
Engineers
In selecting suitable material, one is interested to
know its _________.
Strength
The ability of element of the structure to resist
failure under application of external forces is
known as “__________” and the ability to
resist deformation is known as “________” of that
material.
strength of material; stiffness
It has been observed that the material first _______
and then ________ takes place.
deforms; failure
Whenever force acts on body, it undergoes _________ and some resistance to deformation.
deformation
When _________ is removed, the resistance to force will vanish and the body came back to its _________.
external force; original shape and size
This is possible if deformation due to external force is within certain limit known as “__________”.
Elastic Limit
Is the ability of the material to retain its original shape and size perfectly after removal of load.
Elasticity
Is the tendency of solid materials to return to their original shape after forces are applied on them.
Elasticity
When forces are removed, the object will return to its initial shape and size if the material is _________.
elastic
_______________________ (3) are examples of the elastic materials.
Steel cables, rubber bands, springs
Is the limit within which the body behaves
perfectly elastic.
Elastic Limit
Is the limit within which the body behaves
perfectly elastic.
Elastic Limit
Elastic Limit is very ______ for a substance like steel and _____ for a substance like lead.
high; low
Resistance per unit deformation is known as ______.
Stress
Tensile Stress = _______________
Compressive Stress = __________
Positive; Negative
S𝑡𝑟𝑒𝑠𝑠, 𝜎 = 𝐿𝑜𝑎𝑑/𝐴𝑟𝑒𝑎 = 𝑃/𝐴, what is the unit of measurement of stress?
Unit: N/mm^2 or (Pa)scal (Pa, Kpa, Mpa, Gpa)
Types of Stress
Normal, Tangential
Is a stress that occurs when the surface of
the body is loaded by an axial force.
Where,
S𝑡𝑟𝑒𝑠𝑠, 𝜎 = 𝐿𝑜𝑎𝑑/𝐴𝑟𝑒𝑎 = 𝑃/𝐴
𝜎 – Normal Stress
P – Axial Force
A – Cross Sectional Area
Normal Stress
Types of Normal Stress
a. Tensile Stress
b. Compressive Stress
Is the stress state leading to expansion: that is, the length of material tends to increase in the tensile direction.
Tensile Stress
Normal Stress
___________________
- Consider a vertical rod of uniform cross-sectional area A subjected to equal and opposite pulls F at the ends of the rod.
- These pulls tend to lengthen the rod, which is said to be in tension.
- The rod is in equilibrium under the action of the two external forces.
- Thus, a cross section A of the rod is acted on by a downward force equal to the force F exerted by the part of the rod below it and an upward force equal to the force F exerted by the part of the rod above it.
Tensile Stress
Tensile Stress
* The tensile stress at that cross section in the rod is
defined as
𝜎𝑡 = 𝐹/𝐴
Where:
𝜎t - tensile stress in lb/in2 (psi) or N/mm2 (Pa)scal
F - external tensile force (or applied load) in lbs or N
A - stressed cross-sectional area in in2 or mm2
.
Tensile Stress
A tensile stress is also called a normal stress because the external and internal forces are __________ (normal) to the cross-sectional area under consideration.
perpendicular
Tensile Stress
Sample Problem:
Find the stress of the 50 mm diameter rod under tension with an applied force of 200KN.
𝜎𝑡 = 𝐹/𝐴 = 200/𝜋[(100𝑚𝑚^2)/4] =
= 101.91 Pa
_____________ Is a solid material’s ability to
deform under tensile stress
Ductility
A force that attempts to squeeze or compress a material.
Compressive Stress
UTM means?
Universal Testing Machine
- Consider a vertical rod of uniform cross-sectional area A subjected to equal and opposite pushes F at the
ends of the rod. - These pushes tend to shorten the rod, which is said to be in compression.
Compressive Stress
The ______________ in the rod is
𝜎𝑐 = 𝐹/𝐴
Where:
𝜎c - compressive stressin lb/in2 (psi) or N/mm2 (Pa)scal
F - external compressive force (or applied load) in lbs or N
A - stressed cross-sectional area in in2 or mm2
.
compressive stress
Compressive Stress
Sample Problem:
Calculate the compressive strength of a concrete cylinder. The cross-sectional faces of the cylinder each measure 6 inches across, and the cylinder failed at 71,000 pounds of force. What is the compressive strength of that sample of concrete?
Solution:
𝜎𝑐 = 𝐹/𝐴 = 71000 𝑙𝑏𝑠 / 𝜋(3𝑖𝑛𝑐ℎ𝑒𝑠)^2
= 71000 𝑙𝑏𝑠/28.26 𝑖𝑛𝑐ℎ^2
= 2512 psi
A compressive stress is also called a normal stress because the external and internal forces are ________ to the cross-sectional area under consideration.
normal
- Consider a rectangular solid subjected to a
force F acting to the right along its top surface and
an equal and opposite force F acting to the left
along its bottom surface. - Also imagine that the solid consists of layers, each
of area A, parallel to the top and bottom surfaces. - Each layer is acted on by two forces.
- The layer above it exerts a force F to the right, and
the layer below it exerts a force F to the left. - These forces tend to cause one layer to slide, or
finally shear off, with respect to another layer.
Shearing Stress
