The International Mechanical Engineering Congress and Exposition (IMECE) is ASME's largest research and development conference focused primarily on mechanical engineering, but encompasses perspectives from many engineering disciplines.
On Google, you can find a ton of free images but you should be careful of copyright restrictions.
After searching for an image, click on Tools and then on Usage rights. From there, you can pick whichever of the options applies to you for the image you are searching:
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