A client believes an engineer's designs are too costly,but the engineer fears that anything less may endanger the public.But the client insists on lowering the cost,what,in your opinion,should be the line of action of the engineer?
I work as a Mechanical Engineer for a large multinational and I have to tell you that in my company we take product safety very seriously. As an Engineer, you should do everything you can to try to accommodate the customer's requirements; however, if you come to the conclusion that it is simply not possible to reduce the price further without compromising the safety of the product, then you and/or your company should simply decline to provide the product.
If you are forced to choose between making a sale and product safety, you should always choose safety. Firstly, that is the ethical thing to do. Secondly, you and/or your company will be liable for the safety of a product that you sell, not your customer. If you sell a product that is inherently not safe, then you and/or the company will be taking on liability for that and if anyone is injured (or worse), then it can result in lawsuits coming back to you, which may result in the company making a loss on the product overall anyway. Besides that, there is the risk of damage to the company reputation from putting out an unsafe product. Once reputation has been damaged, it can be very difficult to recover, and that can also be very costly, from a longer-term perspective.
In summary: don't provide a product that you know is unsafe. Just don't do it - the risks are too large.