×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Jq from ASTM E1820, Relation to Assumed Elastic Modulus

Jq from ASTM E1820, Relation to Assumed Elastic Modulus

(OP)
Jq from ASTM 1820, Relation to Elastic Modulus

I have a set of fracture toughness test data from a vendor.
The initial submittal used an inappropriate (too high) elastic modulus.
The data was resubmitted after being evaluated using a lower modulus.

Both Jq and Kjq decreased with the lower assumed modulus.  I can see why Kjq would decrease with decreasing elastic modulus.  But why would Jq decrease?  Annex 9 of ASTM E1820 was used.

Thanks,
Mark

RE: Jq from ASTM E1820, Relation to Assumed Elastic Modulus

JQ uses the J vs. Δa data.  The J data is a function of K (see, for example, equations A1.5, A2.5 & A3.5).  Since K is a function of E, J also is a function of E.

Regards,

Cory

Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips Fora.

RE: Jq from ASTM E1820, Relation to Assumed Elastic Modulus

(OP)
Thanks Cory.

Is there a simple way to estimate a new J for a different modulus assumption?

RE: Jq from ASTM E1820, Relation to Assumed Elastic Modulus

Only the elastic J portion (Jel) changes with elastic modulus.  The plastic portion usually is much higher, but that is only after plasticity initiation.  There is an inverse relationship between J and E, so the change can be substantial.

For example, if you originally had data calculated with E = 210 GPa (modulus for ferritic steel), but it really was E = 200 GPa (modulus for austenitic steel, a 5% difference), then Jel will vary by about 5%.

But, if you originally used E = 200 GPa (steel), but the material is aluminum with E = 70 GPa, then the Jel difference is 65%.

Regards,

Cory

Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips Fora.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a partâ€™s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!