There are relatively few animals, sexually dimorphic or not, in which rape is a common tactic by males.
In both Gorillas and Orangs, males are much larger than females, even more so than humans. While rape is apparently the norm among Orangs, I believe it is not found in Gorillas.
Rape is a common breeding tactic in some species of ducks, but is not found in many species of birds where the sexual size discrepancy is much larger.
Sexual size dimorphism has much more to do with competition between males, than with the ability to dominate females for mating. In most species, females have too many options for rejecting an unsuitable mate.
Regarding the statement that “raped women can’t conceive,” this is simply pig-ignorant when applied to humans. However, in many animals females do have the ability to internally short-circuit fertilization by unacceptbale sperm, even if an unsuitable male has managed to copulate either by force or deception.