Following the embarrassing controversy about the so-called "Bendgate" video test showing the iPhone 6 and iPhone 6 Plus apparently bending or showing a slight curvature with a minimum force, especially when the devices were placed inside the users pockets, Cupertino-based tech giant Apple promises that the issue has been resolved.

Engineers at Apple have tweaked the design of the new iPhone 6s with a much sturdier shell and reinforced the smartphones weak points, particularly on its rear shell. Apple has recently released a video test posted on YouTube claiming "no more bending for iPhone 6s".

In the video, the iPhone 6s was shown as have a thicker shell in areas around the Home and volume buttons. MacRumors said the thickness of the new Apple iPhone 6s is now 1.9mm versus 1.14mm of the previous iPhone 6 and iPhone 6 Plus. The much thicker iPhone 6s is expected to resolve the problem of bending under normal usage, the report added.

However, despite having a much thicker and stronger shell, the iPhone 6s is reported to be lighter than its predecessors, the report added. The new iPhone 6s weighs at least 25 grams compared to the 27 grams for the iPhone 6 rear shell, hinting that Apple could be using a new material such as the rumored 7000 Series anodized aluminum for its next-generation smartphones.

Luma Labs co-founder and industrial designer Greg Koenig told TechCrunch in an interview, "The changes Unbox Therapy is showing are perfectly logical adaptations for Apple to have addressed the Bendgate situation. Clearly, adding more material around those known stress points (at the home and volume buttons) is going to improve the overall strength." He added, "The combination of this material addition plus the rumored switch to 7000 series aluminum (which has roughly 3x the yield strength of 6061) should make the iPhone 6s one of the least bendy smartphones ever made."

Koenig said the trick for Apple's sturdier but lighter shell is by using the 7000 series aluminum instead of  the 6000 series aluminum.

"Apple is buying entire smelting runs of aluminum at a time, so the cost difference for them is virtually nothing," Koenig said. "7000 even machines a touch faster than 6000 series, but finishing and anodizing 7000 series is quite challenging. My guess is that Apple climbed the learning curve on how to process 7000 series aluminum parts with the Watch project, and is now leveraging that knowledge to improve the iPhone."

Earlier, Apple explained that instances when an iPhone 6 Plus bending under normal use is "extremely rare," and said only nine complaints were received by the company from thousands of units they have sold. Apple insisted that the iPhone 6 and iPhone 6 Plus feature a "precision engineered unibody enclosure" constructed from 6000 series anodized aluminum and "stainless steel and titanium inserts to reinforce high stress locations" on the devices.

Bending issues are not limited to the iPhone 6 Plus, as previous generations of the iPhone, including the iPhone 5 and the iPhone 5s have also seen complaints of bending after being subjected to a pocket.