Three cases in as many weeks involving the rape of West German women allegedly by U.S. soldiers in the city of Erlangen have put a serious strain on U.S.-West German relations in the community of about 100,000 people just north of Nuremberg.

The last attack occurred on May 14 and things have calmed down some since then, according to Mayor Deitmar Hahlweg, perhaps because of greatly increased patrols by both U.S. military police and West German police and investigations into the crimes by both U.S. Army and West German authorities.

Fritz Kindervater, a police spokesman in Erlangen, says GI crime traditionally has gone up and down over the years but that it has gone up again in recent months, with increasing cases of taxi drivers and people on the street being threatened with knives.

Asked what he thought was causing the increase, Kindervater said "I get the impression that over the last two years, because of the all-volunteer Army, the quality of the soldier has gone down. Some of them come across as totally illiterate and without any internal leadership."

Erlangen is home to about 3,000 soldiers of the Second Brigade of the U.S. Frist Armored Division. In a recent telephone interview, the mayor said, "I must emphasize that over the past 10 or 20 years we did not have as big problem here with soldiers as did other cities."

"But in the last four months or so," he continued, "it is not so much the number of crimes and assaults, though it is higher than before, but that the robbery and rape."

"Then two weeks ago there was a very severe rape," he said, referring to the May 14 incident in which a man was badly beaten and his 21-year-old girlfriend allegedly raped by three men she said were Americans. "This shocked the public and scared them quite a lot."

The other rapes took place on April 26 and May 2. One American GI is being held in one case and no arrests have been made in the others. U.S. to assume Americans were involved" in another case and the West German police say Americans are also being sought in the May 14 attack, a point U.S. officials do not dispute.

Mayor Hahlweg said, "I have the feeling that soldiers should be better prepared for their stay abroad. For a lot of them, it's the first time in a foreign country, and it would be better for the image of the U.S. when they send people out" if they were better prepared.

The rape reports have produced harsh reactions in the local West German newspapers, which described the attacks as of "great brutality." U.S. military officials believe the local papers have sensationalized the situation and unnecessarily provoked the population with such languages. Some officers privately see it as a move to try and oust the troop from the garrison.

The mayor rejects that, saying that soldiers of any nationality can occasionally be troublesome and stressing that "this is no American-go-home movement. We know the necessity of defense and fully accept the presence of the U.S. here."

The situation has created a serious problem for the brigade's commander, Col. John M. Petracca. After the last attack the local police, fearing violence, reportly asked for a three-day restriction on the troops to allow things to cool down.

The Army, however, decided only on an overnight restriction, apparently working on the theory that several thousand men should not be punished for what both American and West German authorities believe to be the deeds of a "minuscule" number of soldiers.

At a meeting with the brigade last week, the military newspaper Stars and Stripes reported that Petracca told the troops that all of their good military performance will go for nothing "because of a handful of people who are casting the rest of us in an extremely bad light."

The colonel cites statistics showing that crime has gone down a bit, with 53 crimes against persons or property in the first four months of this years attributed to U.S. servicemen in comparison to 55 for the last four months of 1978.

West German police believe the rate is increasing, however, and the mayor's point, as well as Kindervater's, is that the crimes are becoming more violent.

According to statisics provided by the Erlangen police, American servicemen account for a relatively high percentage of the resolved crimes in the area, although Kindervater stresses that because it is sometimes easier for victims to identify Americans the percentage can distort the overall crime situation.

In 1978, he says, 86 criminal sexual offense were committed. Of these cases, 66 were resolved , involving 42 people, 13 of whom were U.S. servicemen.

Included in this are nine cases of rape, six of which were solved. There were seven arrests, including three U.S. soldiers.

Of 21 robbery cases, he said, 11 were resolved, involving 16 people, eight of whom were soldiers.

In 363 reported cases of car vandalism in 1978, 70 were resolved involving 60 people, 27 of whom were Americans.