The critical fibre strength for composite is illustrated by the image below.

To compute for critical fibre strength for composite, three essential parameters are needed and these parameters are **Stress in Matrix at Fibre Failure (σ’ _{m}), Fibre Critical Tensile Strength (σ*_{f})** and

**Volume Fraction of the Fibre (V**

_{f}).The formula for calculating critical fibre strength for composite:

σ*_{a} = σ’_{m}(1 – V_{f}) + σ*_{f}V_{f}

Where:

σ*_{a} = Critical Fibre Strength for Composite

σ’_{m} = Stress in Matrix at Fibre Failure

σ*_{f} = Fibre Critical Tensile Strength

V_{f} = Volume Fraction of the Fibre

Let’s solve an example;

Find the critical fibre strength for composite when the stress in matrix at fibre failure is 12, the fibre critical tensile strength is 10 and the volume fraction of the fibre is 9.

This implies that;

σ’_{m} = Stress in Matrix at Fibre Failure = 12

σ*_{f} = Fibre Critical Tensile Strength = 10

V_{f} = Volume Fraction of the Fibre = 9

σ*_{a} = σ’_{m}(1 – V_{f}) + σ*_{f}V_{f}

σ*_{a} = 12(1 – 9) + (10)(9)

σ*_{a} = 12(-8) + (90)

σ*_{a} = (-96) + (90)

σ*_{a} = -6

Therefore, the **critical fibre strength for composite **is **-6 Pa.**

Nickzom Calculator – **The Calculator Encyclopedia** is capable of calculating the critical fibre strength for composite.

To get the answer and workings of the critical fibre strength for composite using the **Nickzom Calculator – The Calculator Encyclopedia. **First, you need to obtain the app.

You can get this app via any of these means:

**Web** – https://www.nickzom.org/calculator-plus

To get access to the **professional **version via web, you need to **register** and **subscribe **to have utter access to all functionalities.

You can also try the **demo **version via https://www.nickzom.org/calculator

**Android (Paid)** – https://play.google.com/store/apps/details?id=org.nickzom.nickzomcalculator

**Android (Free)** – https://play.google.com/store/apps/details?id=com.nickzom.nickzomcalculator

**Apple (Paid)** – https://itunes.apple.com/us/app/nickzom-calculator/id1331162702?mt=8

Once, you have obtained the calculator encyclopedia app, proceed to the **Calculator Map, **then click on **Materials and Metallurgical **under **Engineering****.**

Now, Click on **Composites**** **under **Materials and Metallurgical**

Now, Click on **Critical Fibre Strength for Composite** under **Composites**

The screenshot below displays the page or activity to enter your values, to get the answer for the critical fibre strength for composite according to the respective parameter which is the **Stress in Matrix at Fibre Failure (σ’ _{m}), Fibre Critical Tensile Strength (σ*_{f})** and

**Volume Fraction of the Fibre (V**

_{f}).Now, enter the values appropriately and accordingly for the parameters as required by the **Stress in Matrix at Fibre Failure (σ’ _{m})** is

**12**,

**Fibre Critical Tensile Strength (σ***is

_{f})**10**and

**Volume Fraction of the Fibre (V**is

_{f})**9**.

Finally, Click on Calculate

As you can see from the screenshot above, **Nickzom Calculator**– The Calculator Encyclopedia solves for the critical fibre strength for composite and presents the formula, workings and steps too.