Question

The useful life of a machine bearing depends on its operating temperature, as the following data show. Obtain a functional description of these data. Plot the function and the data on the same plot. Estimate a bearing’s life if it operates at 150°F.

Answer 1

Program plan:

• To write a matlab code to fit the given data of temperature and bearing life with a most suitable function.

• To find the bearing life if it operated at 150 Fahrenheit using the function.

 

Program:

%**********************************************************

%A matlab code is written to fit the given date using the

%suitable equation and find the life of bearing which

%operates at a temperature. The given date and the function

%are plotted and labeled properly.

%**********************************************************

%Program codes

%Declaration of array

T=100:20:220;

%Declaration of array

life=[28 21 15 11 8 6 4];

%Curve fitting, computes the value of coefficient

p=polyfit(T,log10(life),1);

%Computes the value

life1=10.^polyval(p,T);

%Displays text

disp(\'The life of bearing when the temperature is 150 F is\');

%Displays value

disp(10.^polyval(p,150));

%Plotting

plot(T,life,\'.\',T,life1,150,10.^polyval(p,150),\'*\')

%Assigns text to x-axis

xlabel(\'Temperature\')

%Assigns text to y-axis

ylabel(\'Bearing life\')

 

Output:

>> Untitled

The life of bearing when the temperature is 150 F is

12.8284.

 

Output:

>> Untitled

The life of bearing when the temperature is 150 F is

12.8284.