- What is LS-DYNA? …
- Can you explain the difference between an implicit and explicit solver? …
- What are the main features of LS-DYNA? …
- How can you use LS-DYNA to analyze metal forming processes in a manufacturing environment?
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TECHNICAL INTERVIEW ON LS-DYNA : PART -1
What One Should Really Know:
They would all be unity since a perfect square or solid provides the most accurate area or volume calculation and thereby stress calculation.
Just curious if anyone would know some common technical questions I could expect in an interview regarding LS_Dyna/Explicit FEA in an interview. Some topics I thought of:
FEA Interview Questions on Strength of Materials
The ratio of lateral strain to longitudinal strain is Poissons ratio. It ranges from 0 to 0.5 for metals, 0/3 for steel, and 0.5 for rubber.
A higher Poissons ratio reduces the stiffness of axial load
The torsion equation is defined as the geometrical property of a bar’s cross-section that is involved in the axis of the bar. It is the relationship between the angle of twist and applied torque. The SI unit for the torsion equation is m4.
The numerical representation of the torsion equation is as follows:
I = Moment of inertia exerted on the bending axis.
σ = Stress of the fibre at a distance
y from the neutral/centroidal axis.
E = Youngs Modulus of beam material.
R = Curvature radius of this bent beam.
This causes the shaft to twist as shown in (b) and the outer elements of the shaft experience maximum shear stress, tmax = (TR/J) where R is the shaft radius and J is the polar moment of inertia of the shaft.
Modulus of elasticity: 190-215 GPa.
Specific Density: 7750-8050 Kg/m3
Aluminium:
Modulus of elasticity: 67-73 GPa
Specific Density: 2640-2810 Kg/m3.
The ratio of ultimate stress to the permissible stress
Factor of safety = ultimate stress / permissible stress.
The factor of safety, also known as Safety Factor (SF), is a term describing the structural capacity of a system beyond the expected load or actual load.
For Example:
A bridge is made and it is required to carry a weight of vehicles up to 50 KN. But when the bridge is made it is made in such a way that it can carry vehicles of weight up to 100 KN, so we will say that the bridge has a safety factor of 2 (100 KN / 50KN).
The ratio of direct stress to volumetric strain
When a body is subjected to mutually perpendicular and equal direct stresses, the ratio of direct stress to the corresponding volumetric stress and strain is found to be constant for a given material when the deformation is within a certain limit. This ratio is known as the bulk modulus.
By the principle of work, the amount of strain energy in a body is found. When a load acts on a body there will be deformation, which causes movement of the applied load. This load is defined as strain energy.
Explanation:
Note:
The stress-strain graph represents the stress value against the strain value of the given material when the material is subjected to increasing pull from any of the cardinal directions.
There are mainly six points in the graph.
This blog is for people with an FEA background preparing for an interview. Please add to interview questions by commenting on the blog and I will put it up as a post. Most that I put will be for Ls-dyna experience, if the reader can answer the questions in terms of Abacus/Ansys etc please post in comment and it will be published
