Contents

## Is life finite or infinite?

infinite

“Our lives are finite, but **life is infinite**. We are the finite players in the infinite game of life. We come, we go, we’re born, we die, and life still continues with us or without us. There are other players.

## What is the infinite time?

adj. a **having no limits or boundaries in time, space, extent, or magnitude**.

## How do you create infinite life?

As mentioned earlier, if you want to design for infinite life, just **keep all stress amplitudes below the fatigue limit**. As long as even the largest stress amplitude is below the fatigue limit, life will be infinite. But was happens if some amplitudes are above and some are below the fatigue limit.

## Who said life so infinite so Infinity finite?

**Shama Sikander** on Instagram: “Life, so infinite so infinity Finite… . .

## What is infinite life engineering?

What is meant by infinite life? **Ferrous materials have an “infinite life” region defined by an ‘endurance limit**‘. The endurance limit is a specific stress level for a material, where stress cycles below a certain amplitude and mean will not accumulate fatigue damage.

## What is infinite fatigue life?

For many metals, including steel and aluminum, **no damage occurs once a constant amplitude load drops below the endurance limit** (infinite life). This behavior can be represented by a straight line in a logarithmic diagram called S-N curve.

## What is design for finite life?

7.1.2 Design for Finite Life. **When components are designed to survive for 10 ^{3} to 10^{6} number of cycles**, it is called design for finite life. For S-N curve of steel shown in figure 7.1, line AB represents this region. To design for finite life, fatigue strength is taken as design criteria.

## What is the Goodman line?

Goodman criteria (Goodman Line) :- Used for brittle Materials. **A straight line joining Se on the stress amplitude axis and Sat on the mean stress axis** is called the Goodman’s line, According to the Goodman criteria , the triangular region below this line is considered to be safe.

## What is stress life method?

The stress-life method is **typically used for long life situations (millions of cycles) where the stresses are elastic**. This method is often referred to as infinite life design. It is based on the fatigue limit or endurance limit of the material.

## What is cyclic loading?

Cyclic loading is defined as **the loads that are applied, removed, and reapplied, for example on a pavement, in a relatively rapid and repetitive form**. From: New Materials in Civil Engineering, 2020.

## What affects fatigue life?

Fatigue life is affected by **cyclic stresses, residual stresses, material properties, internal defects, grain size, temperature, design geometry, surface quality, oxidation, corrosion**, etc.

## What is basquin equation?

Basquin’s equation is a power law relationship which describes the linear relationship between the applied stress cycles (S) in the y-axis and the number of cycles to failure in the x-axis plotted on a log-log scale.

## What is Basquins law?

Basquin’s law of fatigue states that **the lifetime of the system has a power-law dependence on the external load amplitude, tf∼σ−α0, where the exponent α has a strong material dependence**.

## What is Strain life?

The Strain Life approach **predicts how long a product will survive due to for both elastic and plastic loads**. The Strain Life approach requires a local stress-strain time history (observed at same location) to determine the cycles and corresponding damage to the product.

## What is Coffin Manson equation?

The acceleration factor resulting from the temperature cycle test is the ratio of the product life at normal operating conditions to the life at accelerated test conditions and is given by the Coffin-Manson equation: **AF = (ΔT _{test} / ΔT _{use}) ^{m}**.

**AF = Acceleration Factor**.

**ΔT**

_{test}= Test temperature difference (°C)## What is fatigue strength?

Fatigue strength is **the highest stress that a material can withstand for a given number of cycles without breaking**. Fatigue strength is affected by environmental factors, such as corrosion. The maximum stress that can be applied for a certain number of cycles without fracture is the fatigue strength.

## What is low cycle fatigue and high cycle fatigue?

The difference between low cycle fatigue (LCF) and high cycle fatigue (HCF) has to do with the deformations. **LCF is characterized by repeated plastic deformation (i.e. in each cycle), whereas HCF is characterized by elastic deformation**.