how to show 3 dimensions on x-axis in barchart ? As shown below

You may not get the X axis look but you may get like Year in X axis and Quarter1,.... Quarter4  as Legends, is this in

Qliksense or QlikView ?

You are limited to 2 Dimensions in a bar chart.  You can add alternative dimensions which might help you out.

You may need to concatenate the year and Qtr together (Q1-2015, etc.). 

Are the 3 bars the months in the quarter or are they the Item types?

I doubt that you will get the exact look you have displayed.  But you can come up with something that will work.

I just had this issue and found a solution that worked for me:

1 - Create your bar chart with the 3 dimensions and 1 measure

2 - Make sure your most outward dimension (if you are doing year/month/week, it would be year) is listed first.

3 - On the 'Dimensions' page, click the 'Trellis' button.

4 - If you have a fixed number of years (or first dimensions) this will work best, but now check 'Enable Trellis Chart', then for number of columns, select your fixed number, and number of rows, select 1. 

Hope this helps!